diff options
Diffstat (limited to 'Documentation')
30 files changed, 3677 insertions, 3794 deletions
diff --git a/Documentation/.gitignore b/Documentation/.gitignore new file mode 100644 index 000000000000..53752db253e3 --- /dev/null +++ b/Documentation/.gitignore @@ -0,0 +1 @@ +output diff --git a/Documentation/DocBook/Makefile b/Documentation/DocBook/Makefile index d70f9b68174e..f4482f9b221f 100644 --- a/Documentation/DocBook/Makefile +++ b/Documentation/DocBook/Makefile @@ -14,7 +14,7 @@ DOCBOOKS := z8530book.xml device-drivers.xml \ genericirq.xml s390-drivers.xml uio-howto.xml scsi.xml \ 80211.xml debugobjects.xml sh.xml regulator.xml \ alsa-driver-api.xml writing-an-alsa-driver.xml \ - tracepoint.xml gpu.xml media_api.xml w1.xml \ + tracepoint.xml media_api.xml w1.xml \ writing_musb_glue_layer.xml crypto-API.xml iio.xml include Documentation/DocBook/media/Makefile @@ -33,10 +33,6 @@ PDF_METHOD = $(prefer-db2x) PS_METHOD = $(prefer-db2x) -### -# The targets that may be used. -PHONY += xmldocs sgmldocs psdocs pdfdocs htmldocs mandocs installmandocs cleandocs - targets += $(DOCBOOKS) BOOKS := $(addprefix $(obj)/,$(DOCBOOKS)) xmldocs: $(BOOKS) @@ -63,6 +59,9 @@ installmandocs: mandocs sort -k 2 -k 1 | uniq -f 1 | sed -e 's: :/:' | \ xargs install -m 644 -t /usr/local/man/man9/ +# no-op for the DocBook toolchain +epubdocs: + ### #External programs used KERNELDOCXMLREF = $(srctree)/scripts/kernel-doc-xml-ref diff --git a/Documentation/DocBook/device-drivers.tmpl b/Documentation/DocBook/device-drivers.tmpl index 8c68768ebee5..c3313d45f4d6 100644 --- a/Documentation/DocBook/device-drivers.tmpl +++ b/Documentation/DocBook/device-drivers.tmpl @@ -161,6 +161,10 @@ X!Edrivers/base/interface.c !Iinclude/linux/fence.h !Edrivers/dma-buf/seqno-fence.c !Iinclude/linux/seqno-fence.h +!Edrivers/dma-buf/fence-array.c +!Iinclude/linux/fence-array.h +!Edrivers/dma-buf/reservation.c +!Iinclude/linux/reservation.h !Edrivers/dma-buf/sync_file.c !Iinclude/linux/sync_file.h </sect2> diff --git a/Documentation/DocBook/gpu.tmpl b/Documentation/DocBook/gpu.tmpl deleted file mode 100644 index 7586bf75f62e..000000000000 --- a/Documentation/DocBook/gpu.tmpl +++ /dev/null @@ -1,3540 +0,0 @@ -<?xml version="1.0" encoding="UTF-8"?> -<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN" - "http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" []> - -<book id="gpuDevelopersGuide"> - <bookinfo> - <title>Linux GPU Driver Developer's Guide</title> - - <authorgroup> - <author> - <firstname>Jesse</firstname> - <surname>Barnes</surname> - <contrib>Initial version</contrib> - <affiliation> - <orgname>Intel Corporation</orgname> - <address> - <email>jesse.barnes@intel.com</email> - </address> - </affiliation> - </author> - <author> - <firstname>Laurent</firstname> - <surname>Pinchart</surname> - <contrib>Driver internals</contrib> - <affiliation> - <orgname>Ideas on board SPRL</orgname> - <address> - <email>laurent.pinchart@ideasonboard.com</email> - </address> - </affiliation> - </author> - <author> - <firstname>Daniel</firstname> - <surname>Vetter</surname> - <contrib>Contributions all over the place</contrib> - <affiliation> - <orgname>Intel Corporation</orgname> - <address> - <email>daniel.vetter@ffwll.ch</email> - </address> - </affiliation> - </author> - <author> - <firstname>Lukas</firstname> - <surname>Wunner</surname> - <contrib>vga_switcheroo documentation</contrib> - <affiliation> - <address> - <email>lukas@wunner.de</email> - </address> - </affiliation> - </author> - </authorgroup> - - <copyright> - <year>2008-2009</year> - <year>2013-2014</year> - <holder>Intel Corporation</holder> - </copyright> - <copyright> - <year>2012</year> - <holder>Laurent Pinchart</holder> - </copyright> - <copyright> - <year>2015</year> - <holder>Lukas Wunner</holder> - </copyright> - - <legalnotice> - <para> - The contents of this file may be used under the terms of the GNU - General Public License version 2 (the "GPL") as distributed in - the kernel source COPYING file. - </para> - </legalnotice> - - <revhistory> - <!-- Put document revisions here, newest first. --> - <revision> - <revnumber>1.0</revnumber> - <date>2012-07-13</date> - <authorinitials>LP</authorinitials> - <revremark>Added extensive documentation about driver internals. - </revremark> - </revision> - <revision> - <revnumber>1.1</revnumber> - <date>2015-10-11</date> - <authorinitials>LW</authorinitials> - <revremark>Added vga_switcheroo documentation. - </revremark> - </revision> - </revhistory> - </bookinfo> - -<toc></toc> - -<part id="drmCore"> - <title>DRM Core</title> - <partintro> - <para> - This first part of the GPU Driver Developer's Guide documents core DRM - code, helper libraries for writing drivers and generic userspace - interfaces exposed by DRM drivers. - </para> - </partintro> - - <chapter id="drmIntroduction"> - <title>Introduction</title> - <para> - The Linux DRM layer contains code intended to support the needs - of complex graphics devices, usually containing programmable - pipelines well suited to 3D graphics acceleration. Graphics - drivers in the kernel may make use of DRM functions to make - tasks like memory management, interrupt handling and DMA easier, - and provide a uniform interface to applications. - </para> - <para> - A note on versions: this guide covers features found in the DRM - tree, including the TTM memory manager, output configuration and - mode setting, and the new vblank internals, in addition to all - the regular features found in current kernels. - </para> - <para> - [Insert diagram of typical DRM stack here] - </para> - <sect1> - <title>Style Guidelines</title> - <para> - For consistency this documentation uses American English. Abbreviations - are written as all-uppercase, for example: DRM, KMS, IOCTL, CRTC, and so - on. To aid in reading, documentations make full use of the markup - characters kerneldoc provides: @parameter for function parameters, @member - for structure members, &structure to reference structures and - function() for functions. These all get automatically hyperlinked if - kerneldoc for the referenced objects exists. When referencing entries in - function vtables please use ->vfunc(). Note that kerneldoc does - not support referencing struct members directly, so please add a reference - to the vtable struct somewhere in the same paragraph or at least section. - </para> - <para> - Except in special situations (to separate locked from unlocked variants) - locking requirements for functions aren't documented in the kerneldoc. - Instead locking should be check at runtime using e.g. - <code>WARN_ON(!mutex_is_locked(...));</code>. Since it's much easier to - ignore documentation than runtime noise this provides more value. And on - top of that runtime checks do need to be updated when the locking rules - change, increasing the chances that they're correct. Within the - documentation the locking rules should be explained in the relevant - structures: Either in the comment for the lock explaining what it - protects, or data fields need a note about which lock protects them, or - both. - </para> - <para> - Functions which have a non-<code>void</code> return value should have a - section called "Returns" explaining the expected return values in - different cases and their meanings. Currently there's no consensus whether - that section name should be all upper-case or not, and whether it should - end in a colon or not. Go with the file-local style. Other common section - names are "Notes" with information for dangerous or tricky corner cases, - and "FIXME" where the interface could be cleaned up. - </para> - </sect1> - </chapter> - - <!-- Internals --> - - <chapter id="drmInternals"> - <title>DRM Internals</title> - <para> - This chapter documents DRM internals relevant to driver authors - and developers working to add support for the latest features to - existing drivers. - </para> - <para> - First, we go over some typical driver initialization - requirements, like setting up command buffers, creating an - initial output configuration, and initializing core services. - Subsequent sections cover core internals in more detail, - providing implementation notes and examples. - </para> - <para> - The DRM layer provides several services to graphics drivers, - many of them driven by the application interfaces it provides - through libdrm, the library that wraps most of the DRM ioctls. - These include vblank event handling, memory - management, output management, framebuffer management, command - submission & fencing, suspend/resume support, and DMA - services. - </para> - - <!-- Internals: driver init --> - - <sect1> - <title>Driver Initialization</title> - <para> - At the core of every DRM driver is a <structname>drm_driver</structname> - structure. Drivers typically statically initialize a drm_driver structure, - and then pass it to <function>drm_dev_alloc()</function> to allocate a - device instance. After the device instance is fully initialized it can be - registered (which makes it accessible from userspace) using - <function>drm_dev_register()</function>. - </para> - <para> - The <structname>drm_driver</structname> structure contains static - information that describes the driver and features it supports, and - pointers to methods that the DRM core will call to implement the DRM API. - We will first go through the <structname>drm_driver</structname> static - information fields, and will then describe individual operations in - details as they get used in later sections. - </para> - <sect2> - <title>Driver Information</title> - <sect3> - <title>Driver Features</title> - <para> - Drivers inform the DRM core about their requirements and supported - features by setting appropriate flags in the - <structfield>driver_features</structfield> field. Since those flags - influence the DRM core behaviour since registration time, most of them - must be set to registering the <structname>drm_driver</structname> - instance. - </para> - <synopsis>u32 driver_features;</synopsis> - <variablelist> - <title>Driver Feature Flags</title> - <varlistentry> - <term>DRIVER_USE_AGP</term> - <listitem><para> - Driver uses AGP interface, the DRM core will manage AGP resources. - </para></listitem> - </varlistentry> - <varlistentry> - <term>DRIVER_REQUIRE_AGP</term> - <listitem><para> - Driver needs AGP interface to function. AGP initialization failure - will become a fatal error. - </para></listitem> - </varlistentry> - <varlistentry> - <term>DRIVER_PCI_DMA</term> - <listitem><para> - Driver is capable of PCI DMA, mapping of PCI DMA buffers to - userspace will be enabled. Deprecated. - </para></listitem> - </varlistentry> - <varlistentry> - <term>DRIVER_SG</term> - <listitem><para> - Driver can perform scatter/gather DMA, allocation and mapping of - scatter/gather buffers will be enabled. Deprecated. - </para></listitem> - </varlistentry> - <varlistentry> - <term>DRIVER_HAVE_DMA</term> - <listitem><para> - Driver supports DMA, the userspace DMA API will be supported. - Deprecated. - </para></listitem> - </varlistentry> - <varlistentry> - <term>DRIVER_HAVE_IRQ</term><term>DRIVER_IRQ_SHARED</term> - <listitem><para> - DRIVER_HAVE_IRQ indicates whether the driver has an IRQ handler - managed by the DRM Core. The core will support simple IRQ handler - installation when the flag is set. The installation process is - described in <xref linkend="drm-irq-registration"/>.</para> - <para>DRIVER_IRQ_SHARED indicates whether the device & handler - support shared IRQs (note that this is required of PCI drivers). - </para></listitem> - </varlistentry> - <varlistentry> - <term>DRIVER_GEM</term> - <listitem><para> - Driver use the GEM memory manager. - </para></listitem> - </varlistentry> - <varlistentry> - <term>DRIVER_MODESET</term> - <listitem><para> - Driver supports mode setting interfaces (KMS). - </para></listitem> - </varlistentry> - <varlistentry> - <term>DRIVER_PRIME</term> - <listitem><para> - Driver implements DRM PRIME buffer sharing. - </para></listitem> - </varlistentry> - <varlistentry> - <term>DRIVER_RENDER</term> - <listitem><para> - Driver supports dedicated render nodes. - </para></listitem> - </varlistentry> - <varlistentry> - <term>DRIVER_ATOMIC</term> - <listitem><para> - Driver supports atomic properties. In this case the driver - must implement appropriate obj->atomic_get_property() vfuncs - for any modeset objects with driver specific properties. - </para></listitem> - </varlistentry> - </variablelist> - </sect3> - <sect3> - <title>Major, Minor and Patchlevel</title> - <synopsis>int major; -int minor; -int patchlevel;</synopsis> - <para> - The DRM core identifies driver versions by a major, minor and patch - level triplet. The information is printed to the kernel log at - initialization time and passed to userspace through the - DRM_IOCTL_VERSION ioctl. - </para> - <para> - The major and minor numbers are also used to verify the requested driver - API version passed to DRM_IOCTL_SET_VERSION. When the driver API changes - between minor versions, applications can call DRM_IOCTL_SET_VERSION to - select a specific version of the API. If the requested major isn't equal - to the driver major, or the requested minor is larger than the driver - minor, the DRM_IOCTL_SET_VERSION call will return an error. Otherwise - the driver's set_version() method will be called with the requested - version. - </para> - </sect3> - <sect3> - <title>Name, Description and Date</title> - <synopsis>char *name; -char *desc; -char *date;</synopsis> - <para> - The driver name is printed to the kernel log at initialization time, - used for IRQ registration and passed to userspace through - DRM_IOCTL_VERSION. - </para> - <para> - The driver description is a purely informative string passed to - userspace through the DRM_IOCTL_VERSION ioctl and otherwise unused by - the kernel. - </para> - <para> - The driver date, formatted as YYYYMMDD, is meant to identify the date of - the latest modification to the driver. However, as most drivers fail to - update it, its value is mostly useless. The DRM core prints it to the - kernel log at initialization time and passes it to userspace through the - DRM_IOCTL_VERSION ioctl. - </para> - </sect3> - </sect2> - <sect2> - <title>Device Instance and Driver Handling</title> -!Pdrivers/gpu/drm/drm_drv.c driver instance overview -!Edrivers/gpu/drm/drm_drv.c - </sect2> - <sect2> - <title>Driver Load</title> - <sect3 id="drm-irq-registration"> - <title>IRQ Registration</title> - <para> - The DRM core tries to facilitate IRQ handler registration and - unregistration by providing <function>drm_irq_install</function> and - <function>drm_irq_uninstall</function> functions. Those functions only - support a single interrupt per device, devices that use more than one - IRQs need to be handled manually. - </para> - <sect4> - <title>Managed IRQ Registration</title> - <para> - <function>drm_irq_install</function> starts by calling the - <methodname>irq_preinstall</methodname> driver operation. The operation - is optional and must make sure that the interrupt will not get fired by - clearing all pending interrupt flags or disabling the interrupt. - </para> - <para> - The passed-in IRQ will then be requested by a call to - <function>request_irq</function>. If the DRIVER_IRQ_SHARED driver - feature flag is set, a shared (IRQF_SHARED) IRQ handler will be - requested. - </para> - <para> - The IRQ handler function must be provided as the mandatory irq_handler - driver operation. It will get passed directly to - <function>request_irq</function> and thus has the same prototype as all - IRQ handlers. It will get called with a pointer to the DRM device as the - second argument. - </para> - <para> - Finally the function calls the optional - <methodname>irq_postinstall</methodname> driver operation. The operation - usually enables interrupts (excluding the vblank interrupt, which is - enabled separately), but drivers may choose to enable/disable interrupts - at a different time. - </para> - <para> - <function>drm_irq_uninstall</function> is similarly used to uninstall an - IRQ handler. It starts by waking up all processes waiting on a vblank - interrupt to make sure they don't hang, and then calls the optional - <methodname>irq_uninstall</methodname> driver operation. The operation - must disable all hardware interrupts. Finally the function frees the IRQ - by calling <function>free_irq</function>. - </para> - </sect4> - <sect4> - <title>Manual IRQ Registration</title> - <para> - Drivers that require multiple interrupt handlers can't use the managed - IRQ registration functions. In that case IRQs must be registered and - unregistered manually (usually with the <function>request_irq</function> - and <function>free_irq</function> functions, or their devm_* equivalent). - </para> - <para> - When manually registering IRQs, drivers must not set the DRIVER_HAVE_IRQ - driver feature flag, and must not provide the - <methodname>irq_handler</methodname> driver operation. They must set the - <structname>drm_device</structname> <structfield>irq_enabled</structfield> - field to 1 upon registration of the IRQs, and clear it to 0 after - unregistering the IRQs. - </para> - </sect4> - </sect3> - <sect3> - <title>Memory Manager Initialization</title> - <para> - Every DRM driver requires a memory manager which must be initialized at - load time. DRM currently contains two memory managers, the Translation - Table Manager (TTM) and the Graphics Execution Manager (GEM). - This document describes the use of the GEM memory manager only. See - <xref linkend="drm-memory-management"/> for details. - </para> - </sect3> - <sect3> - <title>Miscellaneous Device Configuration</title> - <para> - Another task that may be necessary for PCI devices during configuration - is mapping the video BIOS. On many devices, the VBIOS describes device - configuration, LCD panel timings (if any), and contains flags indicating - device state. Mapping the BIOS can be done using the pci_map_rom() call, - a convenience function that takes care of mapping the actual ROM, - whether it has been shadowed into memory (typically at address 0xc0000) - or exists on the PCI device in the ROM BAR. Note that after the ROM has - been mapped and any necessary information has been extracted, it should - be unmapped; on many devices, the ROM address decoder is shared with - other BARs, so leaving it mapped could cause undesired behaviour like - hangs or memory corruption. - <!--!Fdrivers/pci/rom.c pci_map_rom--> - </para> - </sect3> - </sect2> - <sect2> - <title>Bus-specific Device Registration and PCI Support</title> - <para> - A number of functions are provided to help with device registration. - The functions deal with PCI and platform devices respectively and are - only provided for historical reasons. These are all deprecated and - shouldn't be used in new drivers. Besides that there's a few - helpers for pci drivers. - </para> -!Edrivers/gpu/drm/drm_pci.c -!Edrivers/gpu/drm/drm_platform.c - </sect2> - </sect1> - - <!-- Internals: memory management --> - - <sect1 id="drm-memory-management"> - <title>Memory management</title> - <para> - Modern Linux systems require large amount of graphics memory to store - frame buffers, textures, vertices and other graphics-related data. Given - the very dynamic nature of many of that data, managing graphics memory - efficiently is thus crucial for the graphics stack and plays a central - role in the DRM infrastructure. - </para> - <para> - The DRM core includes two memory managers, namely Translation Table Maps - (TTM) and Graphics Execution Manager (GEM). TTM was the first DRM memory - manager to be developed and tried to be a one-size-fits-them all - solution. It provides a single userspace API to accommodate the need of - all hardware, supporting both Unified Memory Architecture (UMA) devices - and devices with dedicated video RAM (i.e. most discrete video cards). - This resulted in a large, complex piece of code that turned out to be - hard to use for driver development. - </para> - <para> - GEM started as an Intel-sponsored project in reaction to TTM's - complexity. Its design philosophy is completely different: instead of - providing a solution to every graphics memory-related problems, GEM - identified common code between drivers and created a support library to - share it. GEM has simpler initialization and execution requirements than - TTM, but has no video RAM management capabilities and is thus limited to - UMA devices. - </para> - <sect2> - <title>The Translation Table Manager (TTM)</title> - <para> - TTM design background and information belongs here. - </para> - <sect3> - <title>TTM initialization</title> - <warning><para>This section is outdated.</para></warning> - <para> - Drivers wishing to support TTM must fill out a drm_bo_driver - structure. The structure contains several fields with function - pointers for initializing the TTM, allocating and freeing memory, - waiting for command completion and fence synchronization, and memory - migration. See the radeon_ttm.c file for an example of usage. - </para> - <para> - The ttm_global_reference structure is made up of several fields: - </para> - <programlisting> - struct ttm_global_reference { - enum ttm_global_types global_type; - size_t size; - void *object; - int (*init) (struct ttm_global_reference *); - void (*release) (struct ttm_global_reference *); - }; - </programlisting> - <para> - There should be one global reference structure for your memory - manager as a whole, and there will be others for each object - created by the memory manager at runtime. Your global TTM should - have a type of TTM_GLOBAL_TTM_MEM. The size field for the global - object should be sizeof(struct ttm_mem_global), and the init and - release hooks should point at your driver-specific init and - release routines, which probably eventually call - ttm_mem_global_init and ttm_mem_global_release, respectively. - </para> - <para> - Once your global TTM accounting structure is set up and initialized - by calling ttm_global_item_ref() on it, - you need to create a buffer object TTM to - provide a pool for buffer object allocation by clients and the - kernel itself. The type of this object should be TTM_GLOBAL_TTM_BO, - and its size should be sizeof(struct ttm_bo_global). Again, - driver-specific init and release functions may be provided, - likely eventually calling ttm_bo_global_init() and - ttm_bo_global_release(), respectively. Also, like the previous - object, ttm_global_item_ref() is used to create an initial reference - count for the TTM, which will call your initialization function. - </para> - </sect3> - </sect2> - <sect2 id="drm-gem"> - <title>The Graphics Execution Manager (GEM)</title> - <para> - The GEM design approach has resulted in a memory manager that doesn't - provide full coverage of all (or even all common) use cases in its - userspace or kernel API. GEM exposes a set of standard memory-related - operations to userspace and a set of helper functions to drivers, and let - drivers implement hardware-specific operations with their own private API. - </para> - <para> - The GEM userspace API is described in the - <ulink url="http://lwn.net/Articles/283798/"><citetitle>GEM - the Graphics - Execution Manager</citetitle></ulink> article on LWN. While slightly - outdated, the document provides a good overview of the GEM API principles. - Buffer allocation and read and write operations, described as part of the - common GEM API, are currently implemented using driver-specific ioctls. - </para> - <para> - GEM is data-agnostic. It manages abstract buffer objects without knowing - what individual buffers contain. APIs that require knowledge of buffer - contents or purpose, such as buffer allocation or synchronization - primitives, are thus outside of the scope of GEM and must be implemented - using driver-specific ioctls. - </para> - <para> - On a fundamental level, GEM involves several operations: - <itemizedlist> - <listitem>Memory allocation and freeing</listitem> - <listitem>Command execution</listitem> - <listitem>Aperture management at command execution time</listitem> - </itemizedlist> - Buffer object allocation is relatively straightforward and largely - provided by Linux's shmem layer, which provides memory to back each - object. - </para> - <para> - Device-specific operations, such as command execution, pinning, buffer - read & write, mapping, and domain ownership transfers are left to - driver-specific ioctls. - </para> - <sect3> - <title>GEM Initialization</title> - <para> - Drivers that use GEM must set the DRIVER_GEM bit in the struct - <structname>drm_driver</structname> - <structfield>driver_features</structfield> field. The DRM core will - then automatically initialize the GEM core before calling the - <methodname>load</methodname> operation. Behind the scene, this will - create a DRM Memory Manager object which provides an address space - pool for object allocation. - </para> - <para> - In a KMS configuration, drivers need to allocate and initialize a - command ring buffer following core GEM initialization if required by - the hardware. UMA devices usually have what is called a "stolen" - memory region, which provides space for the initial framebuffer and - large, contiguous memory regions required by the device. This space is - typically not managed by GEM, and must be initialized separately into - its own DRM MM object. - </para> - </sect3> - <sect3> - <title>GEM Objects Creation</title> - <para> - GEM splits creation of GEM objects and allocation of the memory that - backs them in two distinct operations. - </para> - <para> - GEM objects are represented by an instance of struct - <structname>drm_gem_object</structname>. Drivers usually need to extend - GEM objects with private information and thus create a driver-specific - GEM object structure type that embeds an instance of struct - <structname>drm_gem_object</structname>. - </para> - <para> - To create a GEM object, a driver allocates memory for an instance of its - specific GEM object type and initializes the embedded struct - <structname>drm_gem_object</structname> with a call to - <function>drm_gem_object_init</function>. The function takes a pointer to - the DRM device, a pointer to the GEM object and the buffer object size - in bytes. - </para> - <para> - GEM uses shmem to allocate anonymous pageable memory. - <function>drm_gem_object_init</function> will create an shmfs file of - the requested size and store it into the struct - <structname>drm_gem_object</structname> <structfield>filp</structfield> - field. The memory is used as either main storage for the object when the - graphics hardware uses system memory directly or as a backing store - otherwise. - </para> - <para> - Drivers are responsible for the actual physical pages allocation by - calling <function>shmem_read_mapping_page_gfp</function> for each page. - Note that they can decide to allocate pages when initializing the GEM - object, or to delay allocation until the memory is needed (for instance - when a page fault occurs as a result of a userspace memory access or - when the driver needs to start a DMA transfer involving the memory). - </para> - <para> - Anonymous pageable memory allocation is not always desired, for instance - when the hardware requires physically contiguous system memory as is - often the case in embedded devices. Drivers can create GEM objects with - no shmfs backing (called private GEM objects) by initializing them with - a call to <function>drm_gem_private_object_init</function> instead of - <function>drm_gem_object_init</function>. Storage for private GEM - objects must be managed by drivers. - </para> - </sect3> - <sect3> - <title>GEM Objects Lifetime</title> - <para> - All GEM objects are reference-counted by the GEM core. References can be - acquired and release by <function>calling drm_gem_object_reference</function> - and <function>drm_gem_object_unreference</function> respectively. The - caller must hold the <structname>drm_device</structname> - <structfield>struct_mutex</structfield> lock when calling - <function>drm_gem_object_reference</function>. As a convenience, GEM - provides <function>drm_gem_object_unreference_unlocked</function> - functions that can be called without holding the lock. - </para> - <para> - When the last reference to a GEM object is released the GEM core calls - the <structname>drm_driver</structname> - <methodname>gem_free_object</methodname> operation. That operation is - mandatory for GEM-enabled drivers and must free the GEM object and all - associated resources. - </para> - <para> - <synopsis>void (*gem_free_object) (struct drm_gem_object *obj);</synopsis> - Drivers are responsible for freeing all GEM object resources. This includes - the resources created by the GEM core, which need to be released with - <function>drm_gem_object_release</function>. - </para> - </sect3> - <sect3> - <title>GEM Objects Naming</title> - <para> - Communication between userspace and the kernel refers to GEM objects - using local handles, global names or, more recently, file descriptors. - All of those are 32-bit integer values; the usual Linux kernel limits - apply to the file descriptors. - </para> - <para> - GEM handles are local to a DRM file. Applications get a handle to a GEM - object through a driver-specific ioctl, and can use that handle to refer - to the GEM object in other standard or driver-specific ioctls. Closing a - DRM file handle frees all its GEM handles and dereferences the - associated GEM objects. - </para> - <para> - To create a handle for a GEM object drivers call - <function>drm_gem_handle_create</function>. The function takes a pointer - to the DRM file and the GEM object and returns a locally unique handle. - When the handle is no longer needed drivers delete it with a call to - <function>drm_gem_handle_delete</function>. Finally the GEM object - associated with a handle can be retrieved by a call to - <function>drm_gem_object_lookup</function>. - </para> - <para> - Handles don't take ownership of GEM objects, they only take a reference - to the object that will be dropped when the handle is destroyed. To - avoid leaking GEM objects, drivers must make sure they drop the - reference(s) they own (such as the initial reference taken at object - creation time) as appropriate, without any special consideration for the - handle. For example, in the particular case of combined GEM object and - handle creation in the implementation of the - <methodname>dumb_create</methodname> operation, drivers must drop the - initial reference to the GEM object before returning the handle. - </para> - <para> - GEM names are similar in purpose to handles but are not local to DRM - files. They can be passed between processes to reference a GEM object - globally. Names can't be used directly to refer to objects in the DRM - API, applications must convert handles to names and names to handles - using the DRM_IOCTL_GEM_FLINK and DRM_IOCTL_GEM_OPEN ioctls - respectively. The conversion is handled by the DRM core without any - driver-specific support. - </para> - <para> - GEM also supports buffer sharing with dma-buf file descriptors through - PRIME. GEM-based drivers must use the provided helpers functions to - implement the exporting and importing correctly. See <xref linkend="drm-prime-support" />. - Since sharing file descriptors is inherently more secure than the - easily guessable and global GEM names it is the preferred buffer - sharing mechanism. Sharing buffers through GEM names is only supported - for legacy userspace. Furthermore PRIME also allows cross-device - buffer sharing since it is based on dma-bufs. - </para> - </sect3> - <sect3 id="drm-gem-objects-mapping"> - <title>GEM Objects Mapping</title> - <para> - Because mapping operations are fairly heavyweight GEM favours - read/write-like access to buffers, implemented through driver-specific - ioctls, over mapping buffers to userspace. However, when random access - to the buffer is needed (to perform software rendering for instance), - direct access to the object can be more efficient. - </para> - <para> - The mmap system call can't be used directly to map GEM objects, as they - don't have their own file handle. Two alternative methods currently - co-exist to map GEM objects to userspace. The first method uses a - driver-specific ioctl to perform the mapping operation, calling - <function>do_mmap</function> under the hood. This is often considered - dubious, seems to be discouraged for new GEM-enabled drivers, and will - thus not be described here. - </para> - <para> - The second method uses the mmap system call on the DRM file handle. - <synopsis>void *mmap(void *addr, size_t length, int prot, int flags, int fd, - off_t offset);</synopsis> - DRM identifies the GEM object to be mapped by a fake offset passed - through the mmap offset argument. Prior to being mapped, a GEM object - must thus be associated with a fake offset. To do so, drivers must call - <function>drm_gem_create_mmap_offset</function> on the object. - </para> - <para> - Once allocated, the fake offset value - must be passed to the application in a driver-specific way and can then - be used as the mmap offset argument. - </para> - <para> - The GEM core provides a helper method <function>drm_gem_mmap</function> - to handle object mapping. The method can be set directly as the mmap - file operation handler. It will look up the GEM object based on the - offset value and set the VMA operations to the - <structname>drm_driver</structname> <structfield>gem_vm_ops</structfield> - field. Note that <function>drm_gem_mmap</function> doesn't map memory to - userspace, but relies on the driver-provided fault handler to map pages - individually. - </para> - <para> - To use <function>drm_gem_mmap</function>, drivers must fill the struct - <structname>drm_driver</structname> <structfield>gem_vm_ops</structfield> - field with a pointer to VM operations. - </para> - <para> - <synopsis>struct vm_operations_struct *gem_vm_ops - - struct vm_operations_struct { - void (*open)(struct vm_area_struct * area); - void (*close)(struct vm_area_struct * area); - int (*fault)(struct vm_area_struct *vma, struct vm_fault *vmf); - };</synopsis> - </para> - <para> - The <methodname>open</methodname> and <methodname>close</methodname> - operations must update the GEM object reference count. Drivers can use - the <function>drm_gem_vm_open</function> and - <function>drm_gem_vm_close</function> helper functions directly as open - and close handlers. - </para> - <para> - The fault operation handler is responsible for mapping individual pages - to userspace when a page fault occurs. Depending on the memory - allocation scheme, drivers can allocate pages at fault time, or can - decide to allocate memory for the GEM object at the time the object is - created. - </para> - <para> - Drivers that want to map the GEM object upfront instead of handling page - faults can implement their own mmap file operation handler. - </para> - </sect3> - <sect3> - <title>Memory Coherency</title> - <para> - When mapped to the device or used in a command buffer, backing pages - for an object are flushed to memory and marked write combined so as to - be coherent with the GPU. Likewise, if the CPU accesses an object - after the GPU has finished rendering to the object, then the object - must be made coherent with the CPU's view of memory, usually involving - GPU cache flushing of various kinds. This core CPU<->GPU - coherency management is provided by a device-specific ioctl, which - evaluates an object's current domain and performs any necessary - flushing or synchronization to put the object into the desired - coherency domain (note that the object may be busy, i.e. an active - render target; in that case, setting the domain blocks the client and - waits for rendering to complete before performing any necessary - flushing operations). - </para> - </sect3> - <sect3> - <title>Command Execution</title> - <para> - Perhaps the most important GEM function for GPU devices is providing a - command execution interface to clients. Client programs construct - command buffers containing references to previously allocated memory - objects, and then submit them to GEM. At that point, GEM takes care to - bind all the objects into the GTT, execute the buffer, and provide - necessary synchronization between clients accessing the same buffers. - This often involves evicting some objects from the GTT and re-binding - others (a fairly expensive operation), and providing relocation - support which hides fixed GTT offsets from clients. Clients must take - care not to submit command buffers that reference more objects than - can fit in the GTT; otherwise, GEM will reject them and no rendering - will occur. Similarly, if several objects in the buffer require fence - registers to be allocated for correct rendering (e.g. 2D blits on - pre-965 chips), care must be taken not to require more fence registers - than are available to the client. Such resource management should be - abstracted from the client in libdrm. - </para> - </sect3> - </sect2> - <sect2> - <title>GEM Function Reference</title> -!Edrivers/gpu/drm/drm_gem.c -!Iinclude/drm/drm_gem.h - </sect2> - <sect2> - <title>VMA Offset Manager</title> -!Pdrivers/gpu/drm/drm_vma_manager.c vma offset manager -!Edrivers/gpu/drm/drm_vma_manager.c -!Iinclude/drm/drm_vma_manager.h - </sect2> - <sect2 id="drm-prime-support"> - <title>PRIME Buffer Sharing</title> - <para> - PRIME is the cross device buffer sharing framework in drm, originally - created for the OPTIMUS range of multi-gpu platforms. To userspace - PRIME buffers are dma-buf based file descriptors. - </para> - <sect3> - <title>Overview and Driver Interface</title> - <para> - Similar to GEM global names, PRIME file descriptors are - also used to share buffer objects across processes. They offer - additional security: as file descriptors must be explicitly sent over - UNIX domain sockets to be shared between applications, they can't be - guessed like the globally unique GEM names. - </para> - <para> - Drivers that support the PRIME - API must set the DRIVER_PRIME bit in the struct - <structname>drm_driver</structname> - <structfield>driver_features</structfield> field, and implement the - <methodname>prime_handle_to_fd</methodname> and - <methodname>prime_fd_to_handle</methodname> operations. - </para> - <para> - <synopsis>int (*prime_handle_to_fd)(struct drm_device *dev, - struct drm_file *file_priv, uint32_t handle, - uint32_t flags, int *prime_fd); -int (*prime_fd_to_handle)(struct drm_device *dev, - struct drm_file *file_priv, int prime_fd, - uint32_t *handle);</synopsis> - Those two operations convert a handle to a PRIME file descriptor and - vice versa. Drivers must use the kernel dma-buf buffer sharing framework - to manage the PRIME file descriptors. Similar to the mode setting - API PRIME is agnostic to the underlying buffer object manager, as - long as handles are 32bit unsigned integers. - </para> - <para> - While non-GEM drivers must implement the operations themselves, GEM - drivers must use the <function>drm_gem_prime_handle_to_fd</function> - and <function>drm_gem_prime_fd_to_handle</function> helper functions. - Those helpers rely on the driver - <methodname>gem_prime_export</methodname> and - <methodname>gem_prime_import</methodname> operations to create a dma-buf - instance from a GEM object (dma-buf exporter role) and to create a GEM - object from a dma-buf instance (dma-buf importer role). - </para> - <para> - <synopsis>struct dma_buf * (*gem_prime_export)(struct drm_device *dev, - struct drm_gem_object *obj, - int flags); -struct drm_gem_object * (*gem_prime_import)(struct drm_device *dev, - struct dma_buf *dma_buf);</synopsis> - These two operations are mandatory for GEM drivers that support - PRIME. - </para> - </sect3> - <sect3> - <title>PRIME Helper Functions</title> -!Pdrivers/gpu/drm/drm_prime.c PRIME Helpers - </sect3> - </sect2> - <sect2> - <title>PRIME Function References</title> -!Edrivers/gpu/drm/drm_prime.c - </sect2> - <sect2> - <title>DRM MM Range Allocator</title> - <sect3> - <title>Overview</title> -!Pdrivers/gpu/drm/drm_mm.c Overview - </sect3> - <sect3> - <title>LRU Scan/Eviction Support</title> -!Pdrivers/gpu/drm/drm_mm.c lru scan roaster - </sect3> - </sect2> - <sect2> - <title>DRM MM Range Allocator Function References</title> -!Edrivers/gpu/drm/drm_mm.c -!Iinclude/drm/drm_mm.h - </sect2> - <sect2> - <title>CMA Helper Functions Reference</title> -!Pdrivers/gpu/drm/drm_gem_cma_helper.c cma helpers -!Edrivers/gpu/drm/drm_gem_cma_helper.c -!Iinclude/drm/drm_gem_cma_helper.h - </sect2> - </sect1> - - <!-- Internals: mode setting --> - - <sect1 id="drm-mode-setting"> - <title>Mode Setting</title> - <para> - Drivers must initialize the mode setting core by calling - <function>drm_mode_config_init</function> on the DRM device. The function - initializes the <structname>drm_device</structname> - <structfield>mode_config</structfield> field and never fails. Once done, - mode configuration must be setup by initializing the following fields. - </para> - <itemizedlist> - <listitem> - <synopsis>int min_width, min_height; -int max_width, max_height;</synopsis> - <para> - Minimum and maximum width and height of the frame buffers in pixel - units. - </para> - </listitem> - <listitem> - <synopsis>struct drm_mode_config_funcs *funcs;</synopsis> - <para>Mode setting functions.</para> - </listitem> - </itemizedlist> - <sect2> - <title>Display Modes Function Reference</title> -!Iinclude/drm/drm_modes.h -!Edrivers/gpu/drm/drm_modes.c - </sect2> - <sect2> - <title>Atomic Mode Setting Function Reference</title> -!Edrivers/gpu/drm/drm_atomic.c -!Idrivers/gpu/drm/drm_atomic.c - </sect2> - <sect2> - <title>Frame Buffer Abstraction</title> - <para> - Frame buffers are abstract memory objects that provide a source of - pixels to scanout to a CRTC. Applications explicitly request the - creation of frame buffers through the DRM_IOCTL_MODE_ADDFB(2) ioctls and - receive an opaque handle that can be passed to the KMS CRTC control, - plane configuration and page flip functions. - </para> - <para> - Frame buffers rely on the underneath memory manager for low-level memory - operations. When creating a frame buffer applications pass a memory - handle (or a list of memory handles for multi-planar formats) through - the <parameter>drm_mode_fb_cmd2</parameter> argument. For drivers using - GEM as their userspace buffer management interface this would be a GEM - handle. Drivers are however free to use their own backing storage object - handles, e.g. vmwgfx directly exposes special TTM handles to userspace - and so expects TTM handles in the create ioctl and not GEM handles. - </para> - <para> - The lifetime of a drm framebuffer is controlled with a reference count, - drivers can grab additional references with - <function>drm_framebuffer_reference</function>and drop them - again with <function>drm_framebuffer_unreference</function>. For - driver-private framebuffers for which the last reference is never - dropped (e.g. for the fbdev framebuffer when the struct - <structname>drm_framebuffer</structname> is embedded into the fbdev - helper struct) drivers can manually clean up a framebuffer at module - unload time with - <function>drm_framebuffer_unregister_private</function>. - </para> - </sect2> - <sect2> - <title>Dumb Buffer Objects</title> - <para> - The KMS API doesn't standardize backing storage object creation and - leaves it to driver-specific ioctls. Furthermore actually creating a - buffer object even for GEM-based drivers is done through a - driver-specific ioctl - GEM only has a common userspace interface for - sharing and destroying objects. While not an issue for full-fledged - graphics stacks that include device-specific userspace components (in - libdrm for instance), this limit makes DRM-based early boot graphics - unnecessarily complex. - </para> - <para> - Dumb objects partly alleviate the problem by providing a standard - API to create dumb buffers suitable for scanout, which can then be used - to create KMS frame buffers. - </para> - <para> - To support dumb objects drivers must implement the - <methodname>dumb_create</methodname>, - <methodname>dumb_destroy</methodname> and - <methodname>dumb_map_offset</methodname> operations. - </para> - <itemizedlist> - <listitem> - <synopsis>int (*dumb_create)(struct drm_file *file_priv, struct drm_device *dev, - struct drm_mode_create_dumb *args);</synopsis> - <para> - The <methodname>dumb_create</methodname> operation creates a driver - object (GEM or TTM handle) suitable for scanout based on the - width, height and depth from the struct - <structname>drm_mode_create_dumb</structname> argument. It fills the - argument's <structfield>handle</structfield>, - <structfield>pitch</structfield> and <structfield>size</structfield> - fields with a handle for the newly created object and its line - pitch and size in bytes. - </para> - </listitem> - <listitem> - <synopsis>int (*dumb_destroy)(struct drm_file *file_priv, struct drm_device *dev, - uint32_t handle);</synopsis> - <para> - The <methodname>dumb_destroy</methodname> operation destroys a dumb - object created by <methodname>dumb_create</methodname>. - </para> - </listitem> - <listitem> - <synopsis>int (*dumb_map_offset)(struct drm_file *file_priv, struct drm_device *dev, - uint32_t handle, uint64_t *offset);</synopsis> - <para> - The <methodname>dumb_map_offset</methodname> operation associates an - mmap fake offset with the object given by the handle and returns - it. Drivers must use the - <function>drm_gem_create_mmap_offset</function> function to - associate the fake offset as described in - <xref linkend="drm-gem-objects-mapping"/>. - </para> - </listitem> - </itemizedlist> - <para> - Note that dumb objects may not be used for gpu acceleration, as has been - attempted on some ARM embedded platforms. Such drivers really must have - a hardware-specific ioctl to allocate suitable buffer objects. - </para> - </sect2> - <sect2> - <title>Output Polling</title> - <synopsis>void (*output_poll_changed)(struct drm_device *dev);</synopsis> - <para> - This operation notifies the driver that the status of one or more - connectors has changed. Drivers that use the fb helper can just call the - <function>drm_fb_helper_hotplug_event</function> function to handle this - operation. - </para> - </sect2> - <sect2> - <title>Locking</title> - <para> - Beside some lookup structures with their own locking (which is hidden - behind the interface functions) most of the modeset state is protected - by the <code>dev-<mode_config.lock</code> mutex and additionally - per-crtc locks to allow cursor updates, pageflips and similar operations - to occur concurrently with background tasks like output detection. - Operations which cross domains like a full modeset always grab all - locks. Drivers there need to protect resources shared between crtcs with - additional locking. They also need to be careful to always grab the - relevant crtc locks if a modset functions touches crtc state, e.g. for - load detection (which does only grab the <code>mode_config.lock</code> - to allow concurrent screen updates on live crtcs). - </para> - </sect2> - </sect1> - - <!-- Internals: kms initialization and cleanup --> - - <sect1 id="drm-kms-init"> - <title>KMS Initialization and Cleanup</title> - <para> - A KMS device is abstracted and exposed as a set of planes, CRTCs, encoders - and connectors. KMS drivers must thus create and initialize all those - objects at load time after initializing mode setting. - </para> - <sect2> - <title>CRTCs (struct <structname>drm_crtc</structname>)</title> - <para> - A CRTC is an abstraction representing a part of the chip that contains a - pointer to a scanout buffer. Therefore, the number of CRTCs available - determines how many independent scanout buffers can be active at any - given time. The CRTC structure contains several fields to support this: - a pointer to some video memory (abstracted as a frame buffer object), a - display mode, and an (x, y) offset into the video memory to support - panning or configurations where one piece of video memory spans multiple - CRTCs. - </para> - <sect3> - <title>CRTC Initialization</title> - <para> - A KMS device must create and register at least one struct - <structname>drm_crtc</structname> instance. The instance is allocated - and zeroed by the driver, possibly as part of a larger structure, and - registered with a call to <function>drm_crtc_init</function> with a - pointer to CRTC functions. - </para> - </sect3> - </sect2> - <sect2> - <title>Planes (struct <structname>drm_plane</structname>)</title> - <para> - A plane represents an image source that can be blended with or overlayed - on top of a CRTC during the scanout process. Planes are associated with - a frame buffer to crop a portion of the image memory (source) and - optionally scale it to a destination size. The result is then blended - with or overlayed on top of a CRTC. - </para> - <para> - The DRM core recognizes three types of planes: - <itemizedlist> - <listitem> - DRM_PLANE_TYPE_PRIMARY represents a "main" plane for a CRTC. Primary - planes are the planes operated upon by CRTC modesetting and flipping - operations described in the page_flip hook in <structname>drm_crtc_funcs</structname>. - </listitem> - <listitem> - DRM_PLANE_TYPE_CURSOR represents a "cursor" plane for a CRTC. Cursor - planes are the planes operated upon by the DRM_IOCTL_MODE_CURSOR and - DRM_IOCTL_MODE_CURSOR2 ioctls. - </listitem> - <listitem> - DRM_PLANE_TYPE_OVERLAY represents all non-primary, non-cursor planes. - Some drivers refer to these types of planes as "sprites" internally. - </listitem> - </itemizedlist> - For compatibility with legacy userspace, only overlay planes are made - available to userspace by default. Userspace clients may set the - DRM_CLIENT_CAP_UNIVERSAL_PLANES client capability bit to indicate that - they wish to receive a universal plane list containing all plane types. - </para> - <sect3> - <title>Plane Initialization</title> - <para> - To create a plane, a KMS drivers allocates and - zeroes an instances of struct <structname>drm_plane</structname> - (possibly as part of a larger structure) and registers it with a call - to <function>drm_universal_plane_init</function>. The function takes a bitmask - of the CRTCs that can be associated with the plane, a pointer to the - plane functions, a list of format supported formats, and the type of - plane (primary, cursor, or overlay) being initialized. - </para> - <para> - Cursor and overlay planes are optional. All drivers should provide - one primary plane per CRTC (although this requirement may change in - the future); drivers that do not wish to provide special handling for - primary planes may make use of the helper functions described in - <xref linkend="drm-kms-planehelpers"/> to create and register a - primary plane with standard capabilities. - </para> - </sect3> - </sect2> - <sect2> - <title>Encoders (struct <structname>drm_encoder</structname>)</title> - <para> - An encoder takes pixel data from a CRTC and converts it to a format - suitable for any attached connectors. On some devices, it may be - possible to have a CRTC send data to more than one encoder. In that - case, both encoders would receive data from the same scanout buffer, - resulting in a "cloned" display configuration across the connectors - attached to each encoder. - </para> - <sect3> - <title>Encoder Initialization</title> - <para> - As for CRTCs, a KMS driver must create, initialize and register at - least one struct <structname>drm_encoder</structname> instance. The - instance is allocated and zeroed by the driver, possibly as part of a - larger structure. - </para> - <para> - Drivers must initialize the struct <structname>drm_encoder</structname> - <structfield>possible_crtcs</structfield> and - <structfield>possible_clones</structfield> fields before registering the - encoder. Both fields are bitmasks of respectively the CRTCs that the - encoder can be connected to, and sibling encoders candidate for cloning. - </para> - <para> - After being initialized, the encoder must be registered with a call to - <function>drm_encoder_init</function>. The function takes a pointer to - the encoder functions and an encoder type. Supported types are - <itemizedlist> - <listitem> - DRM_MODE_ENCODER_DAC for VGA and analog on DVI-I/DVI-A - </listitem> - <listitem> - DRM_MODE_ENCODER_TMDS for DVI, HDMI and (embedded) DisplayPort - </listitem> - <listitem> - DRM_MODE_ENCODER_LVDS for display panels - </listitem> - <listitem> - DRM_MODE_ENCODER_TVDAC for TV output (Composite, S-Video, Component, - SCART) - </listitem> - <listitem> - DRM_MODE_ENCODER_VIRTUAL for virtual machine displays - </listitem> - </itemizedlist> - </para> - <para> - Encoders must be attached to a CRTC to be used. DRM drivers leave - encoders unattached at initialization time. Applications (or the fbdev - compatibility layer when implemented) are responsible for attaching the - encoders they want to use to a CRTC. - </para> - </sect3> - </sect2> - <sect2> - <title>Connectors (struct <structname>drm_connector</structname>)</title> - <para> - A connector is the final destination for pixel data on a device, and - usually connects directly to an external display device like a monitor - or laptop panel. A connector can only be attached to one encoder at a - time. The connector is also the structure where information about the - attached display is kept, so it contains fields for display data, EDID - data, DPMS & connection status, and information about modes - supported on the attached displays. - </para> - <sect3> - <title>Connector Initialization</title> - <para> - Finally a KMS driver must create, initialize, register and attach at - least one struct <structname>drm_connector</structname> instance. The - instance is created as other KMS objects and initialized by setting the - following fields. - </para> - <variablelist> - <varlistentry> - <term><structfield>interlace_allowed</structfield></term> - <listitem><para> - Whether the connector can handle interlaced modes. - </para></listitem> - </varlistentry> - <varlistentry> - <term><structfield>doublescan_allowed</structfield></term> - <listitem><para> - Whether the connector can handle doublescan. - </para></listitem> - </varlistentry> - <varlistentry> - <term><structfield>display_info - </structfield></term> - <listitem><para> - Display information is filled from EDID information when a display - is detected. For non hot-pluggable displays such as flat panels in - embedded systems, the driver should initialize the - <structfield>display_info</structfield>.<structfield>width_mm</structfield> - and - <structfield>display_info</structfield>.<structfield>height_mm</structfield> - fields with the physical size of the display. - </para></listitem> - </varlistentry> - <varlistentry> - <term id="drm-kms-connector-polled"><structfield>polled</structfield></term> - <listitem><para> - Connector polling mode, a combination of - <variablelist> - <varlistentry> - <term>DRM_CONNECTOR_POLL_HPD</term> - <listitem><para> - The connector generates hotplug events and doesn't need to be - periodically polled. The CONNECT and DISCONNECT flags must not - be set together with the HPD flag. - </para></listitem> - </varlistentry> - <varlistentry> - <term>DRM_CONNECTOR_POLL_CONNECT</term> - <listitem><para> - Periodically poll the connector for connection. - </para></listitem> - </varlistentry> - <varlistentry> - <term>DRM_CONNECTOR_POLL_DISCONNECT</term> - <listitem><para> - Periodically poll the connector for disconnection. - </para></listitem> - </varlistentry> - </variablelist> - Set to 0 for connectors that don't support connection status - discovery. - </para></listitem> - </varlistentry> - </variablelist> - <para> - The connector is then registered with a call to - <function>drm_connector_init</function> with a pointer to the connector - functions and a connector type, and exposed through sysfs with a call to - <function>drm_connector_register</function>. - </para> - <para> - Supported connector types are - <itemizedlist> - <listitem>DRM_MODE_CONNECTOR_VGA</listitem> - <listitem>DRM_MODE_CONNECTOR_DVII</listitem> - <listitem>DRM_MODE_CONNECTOR_DVID</listitem> - <listitem>DRM_MODE_CONNECTOR_DVIA</listitem> - <listitem>DRM_MODE_CONNECTOR_Composite</listitem> - <listitem>DRM_MODE_CONNECTOR_SVIDEO</listitem> - <listitem>DRM_MODE_CONNECTOR_LVDS</listitem> - <listitem>DRM_MODE_CONNECTOR_Component</listitem> - <listitem>DRM_MODE_CONNECTOR_9PinDIN</listitem> - <listitem>DRM_MODE_CONNECTOR_DisplayPort</listitem> - <listitem>DRM_MODE_CONNECTOR_HDMIA</listitem> - <listitem>DRM_MODE_CONNECTOR_HDMIB</listitem> - <listitem>DRM_MODE_CONNECTOR_TV</listitem> - <listitem>DRM_MODE_CONNECTOR_eDP</listitem> - <listitem>DRM_MODE_CONNECTOR_VIRTUAL</listitem> - </itemizedlist> - </para> - <para> - Connectors must be attached to an encoder to be used. For devices that - map connectors to encoders 1:1, the connector should be attached at - initialization time with a call to - <function>drm_mode_connector_attach_encoder</function>. The driver must - also set the <structname>drm_connector</structname> - <structfield>encoder</structfield> field to point to the attached - encoder. - </para> - <para> - Finally, drivers must initialize the connectors state change detection - with a call to <function>drm_kms_helper_poll_init</function>. If at - least one connector is pollable but can't generate hotplug interrupts - (indicated by the DRM_CONNECTOR_POLL_CONNECT and - DRM_CONNECTOR_POLL_DISCONNECT connector flags), a delayed work will - automatically be queued to periodically poll for changes. Connectors - that can generate hotplug interrupts must be marked with the - DRM_CONNECTOR_POLL_HPD flag instead, and their interrupt handler must - call <function>drm_helper_hpd_irq_event</function>. The function will - queue a delayed work to check the state of all connectors, but no - periodic polling will be done. - </para> - </sect3> - <sect3> - <title>Connector Operations</title> - <note><para> - Unless otherwise state, all operations are mandatory. - </para></note> - <sect4> - <title>DPMS</title> - <synopsis>void (*dpms)(struct drm_connector *connector, int mode);</synopsis> - <para> - The DPMS operation sets the power state of a connector. The mode - argument is one of - <itemizedlist> - <listitem><para>DRM_MODE_DPMS_ON</para></listitem> - <listitem><para>DRM_MODE_DPMS_STANDBY</para></listitem> - <listitem><para>DRM_MODE_DPMS_SUSPEND</para></listitem> - <listitem><para>DRM_MODE_DPMS_OFF</para></listitem> - </itemizedlist> - </para> - <para> - In all but DPMS_ON mode the encoder to which the connector is attached - should put the display in low-power mode by driving its signals - appropriately. If more than one connector is attached to the encoder - care should be taken not to change the power state of other displays as - a side effect. Low-power mode should be propagated to the encoders and - CRTCs when all related connectors are put in low-power mode. - </para> - </sect4> - <sect4> - <title>Modes</title> - <synopsis>int (*fill_modes)(struct drm_connector *connector, uint32_t max_width, - uint32_t max_height);</synopsis> - <para> - Fill the mode list with all supported modes for the connector. If the - <parameter>max_width</parameter> and <parameter>max_height</parameter> - arguments are non-zero, the implementation must ignore all modes wider - than <parameter>max_width</parameter> or higher than - <parameter>max_height</parameter>. - </para> - <para> - The connector must also fill in this operation its - <structfield>display_info</structfield> - <structfield>width_mm</structfield> and - <structfield>height_mm</structfield> fields with the connected display - physical size in millimeters. The fields should be set to 0 if the value - isn't known or is not applicable (for instance for projector devices). - </para> - </sect4> - <sect4> - <title>Connection Status</title> - <para> - The connection status is updated through polling or hotplug events when - supported (see <xref linkend="drm-kms-connector-polled"/>). The status - value is reported to userspace through ioctls and must not be used - inside the driver, as it only gets initialized by a call to - <function>drm_mode_getconnector</function> from userspace. - </para> - <synopsis>enum drm_connector_status (*detect)(struct drm_connector *connector, - bool force);</synopsis> - <para> - Check to see if anything is attached to the connector. The - <parameter>force</parameter> parameter is set to false whilst polling or - to true when checking the connector due to user request. - <parameter>force</parameter> can be used by the driver to avoid - expensive, destructive operations during automated probing. - </para> - <para> - Return connector_status_connected if something is connected to the - connector, connector_status_disconnected if nothing is connected and - connector_status_unknown if the connection state isn't known. - </para> - <para> - Drivers should only return connector_status_connected if the connection - status has really been probed as connected. Connectors that can't detect - the connection status, or failed connection status probes, should return - connector_status_unknown. - </para> - </sect4> - </sect3> - </sect2> - <sect2> - <title>Cleanup</title> - <para> - The DRM core manages its objects' lifetime. When an object is not needed - anymore the core calls its destroy function, which must clean up and - free every resource allocated for the object. Every - <function>drm_*_init</function> call must be matched with a - corresponding <function>drm_*_cleanup</function> call to cleanup CRTCs - (<function>drm_crtc_cleanup</function>), planes - (<function>drm_plane_cleanup</function>), encoders - (<function>drm_encoder_cleanup</function>) and connectors - (<function>drm_connector_cleanup</function>). Furthermore, connectors - that have been added to sysfs must be removed by a call to - <function>drm_connector_unregister</function> before calling - <function>drm_connector_cleanup</function>. - </para> - <para> - Connectors state change detection must be cleanup up with a call to - <function>drm_kms_helper_poll_fini</function>. - </para> - </sect2> - <sect2> - <title>Output discovery and initialization example</title> - <programlisting><![CDATA[ -void intel_crt_init(struct drm_device *dev) -{ - struct drm_connector *connector; - struct intel_output *intel_output; - - intel_output = kzalloc(sizeof(struct intel_output), GFP_KERNEL); - if (!intel_output) - return; - - connector = &intel_output->base; - drm_connector_init(dev, &intel_output->base, - &intel_crt_connector_funcs, DRM_MODE_CONNECTOR_VGA); - - drm_encoder_init(dev, &intel_output->enc, &intel_crt_enc_funcs, - DRM_MODE_ENCODER_DAC); - - drm_mode_connector_attach_encoder(&intel_output->base, - &intel_output->enc); - - /* Set up the DDC bus. */ - intel_output->ddc_bus = intel_i2c_create(dev, GPIOA, "CRTDDC_A"); - if (!intel_output->ddc_bus) { - dev_printk(KERN_ERR, &dev->pdev->dev, "DDC bus registration " - "failed.\n"); - return; - } - - intel_output->type = INTEL_OUTPUT_ANALOG; - connector->interlace_allowed = 0; - connector->doublescan_allowed = 0; - - drm_encoder_helper_add(&intel_output->enc, &intel_crt_helper_funcs); - drm_connector_helper_add(connector, &intel_crt_connector_helper_funcs); - - drm_connector_register(connector); -}]]></programlisting> - <para> - In the example above (taken from the i915 driver), a CRTC, connector and - encoder combination is created. A device-specific i2c bus is also - created for fetching EDID data and performing monitor detection. Once - the process is complete, the new connector is registered with sysfs to - make its properties available to applications. - </para> - </sect2> - <sect2> - <title>KMS API Functions</title> -!Edrivers/gpu/drm/drm_crtc.c - </sect2> - <sect2> - <title>KMS Data Structures</title> -!Iinclude/drm/drm_crtc.h - </sect2> - <sect2> - <title>KMS Locking</title> -!Pdrivers/gpu/drm/drm_modeset_lock.c kms locking -!Iinclude/drm/drm_modeset_lock.h -!Edrivers/gpu/drm/drm_modeset_lock.c - </sect2> - </sect1> - - <!-- Internals: kms helper functions --> - - <sect1> - <title>Mode Setting Helper Functions</title> - <para> - The plane, CRTC, encoder and connector functions provided by the drivers - implement the DRM API. They're called by the DRM core and ioctl handlers - to handle device state changes and configuration request. As implementing - those functions often requires logic not specific to drivers, mid-layer - helper functions are available to avoid duplicating boilerplate code. - </para> - <para> - The DRM core contains one mid-layer implementation. The mid-layer provides - implementations of several plane, CRTC, encoder and connector functions - (called from the top of the mid-layer) that pre-process requests and call - lower-level functions provided by the driver (at the bottom of the - mid-layer). For instance, the - <function>drm_crtc_helper_set_config</function> function can be used to - fill the struct <structname>drm_crtc_funcs</structname> - <structfield>set_config</structfield> field. When called, it will split - the <methodname>set_config</methodname> operation in smaller, simpler - operations and call the driver to handle them. - </para> - <para> - To use the mid-layer, drivers call <function>drm_crtc_helper_add</function>, - <function>drm_encoder_helper_add</function> and - <function>drm_connector_helper_add</function> functions to install their - mid-layer bottom operations handlers, and fill the - <structname>drm_crtc_funcs</structname>, - <structname>drm_encoder_funcs</structname> and - <structname>drm_connector_funcs</structname> structures with pointers to - the mid-layer top API functions. Installing the mid-layer bottom operation - handlers is best done right after registering the corresponding KMS object. - </para> - <para> - The mid-layer is not split between CRTC, encoder and connector operations. - To use it, a driver must provide bottom functions for all of the three KMS - entities. - </para> - <sect2> - <title>Atomic Modeset Helper Functions Reference</title> - <sect3> - <title>Overview</title> -!Pdrivers/gpu/drm/drm_atomic_helper.c overview - </sect3> - <sect3> - <title>Implementing Asynchronous Atomic Commit</title> -!Pdrivers/gpu/drm/drm_atomic_helper.c implementing async commit - </sect3> - <sect3> - <title>Atomic State Reset and Initialization</title> -!Pdrivers/gpu/drm/drm_atomic_helper.c atomic state reset and initialization - </sect3> -!Iinclude/drm/drm_atomic_helper.h -!Edrivers/gpu/drm/drm_atomic_helper.c - </sect2> - <sect2> - <title>Modeset Helper Reference for Common Vtables</title> -!Iinclude/drm/drm_modeset_helper_vtables.h -!Pinclude/drm/drm_modeset_helper_vtables.h overview - </sect2> - <sect2> - <title>Legacy CRTC/Modeset Helper Functions Reference</title> -!Edrivers/gpu/drm/drm_crtc_helper.c -!Pdrivers/gpu/drm/drm_crtc_helper.c overview - </sect2> - <sect2> - <title>Output Probing Helper Functions Reference</title> -!Pdrivers/gpu/drm/drm_probe_helper.c output probing helper overview -!Edrivers/gpu/drm/drm_probe_helper.c - </sect2> - <sect2> - <title>fbdev Helper Functions Reference</title> -!Pdrivers/gpu/drm/drm_fb_helper.c fbdev helpers -!Edrivers/gpu/drm/drm_fb_helper.c -!Iinclude/drm/drm_fb_helper.h - </sect2> - <sect2> - <title>Framebuffer CMA Helper Functions Reference</title> -!Pdrivers/gpu/drm/drm_fb_cma_helper.c framebuffer cma helper functions -!Edrivers/gpu/drm/drm_fb_cma_helper.c - </sect2> - <sect2> - <title>Display Port Helper Functions Reference</title> -!Pdrivers/gpu/drm/drm_dp_helper.c dp helpers -!Iinclude/drm/drm_dp_helper.h -!Edrivers/gpu/drm/drm_dp_helper.c - </sect2> - <sect2> - <title>Display Port Dual Mode Adaptor Helper Functions Reference</title> -!Pdrivers/gpu/drm/drm_dp_dual_mode_helper.c dp dual mode helpers -!Iinclude/drm/drm_dp_dual_mode_helper.h -!Edrivers/gpu/drm/drm_dp_dual_mode_helper.c - </sect2> - <sect2> - <title>Display Port MST Helper Functions Reference</title> -!Pdrivers/gpu/drm/drm_dp_mst_topology.c dp mst helper -!Iinclude/drm/drm_dp_mst_helper.h -!Edrivers/gpu/drm/drm_dp_mst_topology.c - </sect2> - <sect2> - <title>MIPI DSI Helper Functions Reference</title> -!Pdrivers/gpu/drm/drm_mipi_dsi.c dsi helpers -!Iinclude/drm/drm_mipi_dsi.h -!Edrivers/gpu/drm/drm_mipi_dsi.c - </sect2> - <sect2> - <title>EDID Helper Functions Reference</title> -!Edrivers/gpu/drm/drm_edid.c - </sect2> - <sect2> - <title>Rectangle Utilities Reference</title> -!Pinclude/drm/drm_rect.h rect utils -!Iinclude/drm/drm_rect.h -!Edrivers/gpu/drm/drm_rect.c - </sect2> - <sect2> - <title>Flip-work Helper Reference</title> -!Pinclude/drm/drm_flip_work.h flip utils -!Iinclude/drm/drm_flip_work.h -!Edrivers/gpu/drm/drm_flip_work.c - </sect2> - <sect2> - <title>HDMI Infoframes Helper Reference</title> - <para> - Strictly speaking this is not a DRM helper library but generally useable - by any driver interfacing with HDMI outputs like v4l or alsa drivers. - But it nicely fits into the overall topic of mode setting helper - libraries and hence is also included here. - </para> -!Iinclude/linux/hdmi.h -!Edrivers/video/hdmi.c - </sect2> - <sect2> - <title id="drm-kms-planehelpers">Plane Helper Reference</title> -!Edrivers/gpu/drm/drm_plane_helper.c -!Pdrivers/gpu/drm/drm_plane_helper.c overview - </sect2> - <sect2> - <title>Tile group</title> -!Pdrivers/gpu/drm/drm_crtc.c Tile group - </sect2> - <sect2> - <title>Bridges</title> - <sect3> - <title>Overview</title> -!Pdrivers/gpu/drm/drm_bridge.c overview - </sect3> - <sect3> - <title>Default bridge callback sequence</title> -!Pdrivers/gpu/drm/drm_bridge.c bridge callbacks - </sect3> -!Edrivers/gpu/drm/drm_bridge.c - </sect2> - <sect2> - <title>Panel Helper Reference</title> -!Iinclude/drm/drm_panel.h -!Edrivers/gpu/drm/drm_panel.c -!Pdrivers/gpu/drm/drm_panel.c drm panel - </sect2> - </sect1> - - <!-- Internals: kms properties --> - - <sect1 id="drm-kms-properties"> - <title>KMS Properties</title> - <para> - Drivers may need to expose additional parameters to applications than - those described in the previous sections. KMS supports attaching - properties to CRTCs, connectors and planes and offers a userspace API to - list, get and set the property values. - </para> - <para> - Properties are identified by a name that uniquely defines the property - purpose, and store an associated value. For all property types except blob - properties the value is a 64-bit unsigned integer. - </para> - <para> - KMS differentiates between properties and property instances. Drivers - first create properties and then create and associate individual instances - of those properties to objects. A property can be instantiated multiple - times and associated with different objects. Values are stored in property - instances, and all other property information are stored in the property - and shared between all instances of the property. - </para> - <para> - Every property is created with a type that influences how the KMS core - handles the property. Supported property types are - <variablelist> - <varlistentry> - <term>DRM_MODE_PROP_RANGE</term> - <listitem><para>Range properties report their minimum and maximum - admissible values. The KMS core verifies that values set by - application fit in that range.</para></listitem> - </varlistentry> - <varlistentry> - <term>DRM_MODE_PROP_ENUM</term> - <listitem><para>Enumerated properties take a numerical value that - ranges from 0 to the number of enumerated values defined by the - property minus one, and associate a free-formed string name to each - value. Applications can retrieve the list of defined value-name pairs - and use the numerical value to get and set property instance values. - </para></listitem> - </varlistentry> - <varlistentry> - <term>DRM_MODE_PROP_BITMASK</term> - <listitem><para>Bitmask properties are enumeration properties that - additionally restrict all enumerated values to the 0..63 range. - Bitmask property instance values combine one or more of the - enumerated bits defined by the property.</para></listitem> - </varlistentry> - <varlistentry> - <term>DRM_MODE_PROP_BLOB</term> - <listitem><para>Blob properties store a binary blob without any format - restriction. The binary blobs are created as KMS standalone objects, - and blob property instance values store the ID of their associated - blob object.</para> - <para>Blob properties are only used for the connector EDID property - and cannot be created by drivers.</para></listitem> - </varlistentry> - </variablelist> - </para> - <para> - To create a property drivers call one of the following functions depending - on the property type. All property creation functions take property flags - and name, as well as type-specific arguments. - <itemizedlist> - <listitem> - <synopsis>struct drm_property *drm_property_create_range(struct drm_device *dev, int flags, - const char *name, - uint64_t min, uint64_t max);</synopsis> - <para>Create a range property with the given minimum and maximum - values.</para> - </listitem> - <listitem> - <synopsis>struct drm_property *drm_property_create_enum(struct drm_device *dev, int flags, - const char *name, - const struct drm_prop_enum_list *props, - int num_values);</synopsis> - <para>Create an enumerated property. The <parameter>props</parameter> - argument points to an array of <parameter>num_values</parameter> - value-name pairs.</para> - </listitem> - <listitem> - <synopsis>struct drm_property *drm_property_create_bitmask(struct drm_device *dev, - int flags, const char *name, - const struct drm_prop_enum_list *props, - int num_values);</synopsis> - <para>Create a bitmask property. The <parameter>props</parameter> - argument points to an array of <parameter>num_values</parameter> - value-name pairs.</para> - </listitem> - </itemizedlist> - </para> - <para> - Properties can additionally be created as immutable, in which case they - will be read-only for applications but can be modified by the driver. To - create an immutable property drivers must set the DRM_MODE_PROP_IMMUTABLE - flag at property creation time. - </para> - <para> - When no array of value-name pairs is readily available at property - creation time for enumerated or range properties, drivers can create - the property using the <function>drm_property_create</function> function - and manually add enumeration value-name pairs by calling the - <function>drm_property_add_enum</function> function. Care must be taken to - properly specify the property type through the <parameter>flags</parameter> - argument. - </para> - <para> - After creating properties drivers can attach property instances to CRTC, - connector and plane objects by calling the - <function>drm_object_attach_property</function>. The function takes a - pointer to the target object, a pointer to the previously created property - and an initial instance value. - </para> - <sect2> - <title>Existing KMS Properties</title> - <para> - The following table gives description of drm properties exposed by various - modules/drivers. - </para> - <table border="1" cellpadding="0" cellspacing="0"> - <tbody> - <tr style="font-weight: bold;"> - <td valign="top" >Owner Module/Drivers</td> - <td valign="top" >Group</td> - <td valign="top" >Property Name</td> - <td valign="top" >Type</td> - <td valign="top" >Property Values</td> - <td valign="top" >Object attached</td> - <td valign="top" >Description/Restrictions</td> - </tr> - <tr> - <td rowspan="42" valign="top" >DRM</td> - <td rowspan="2" valign="top" >Generic</td> - <td valign="top" >“rotation”</td> - <td valign="top" >BITMASK</td> - <td valign="top" >{ 0, "rotate-0" }, - { 1, "rotate-90" }, - { 2, "rotate-180" }, - { 3, "rotate-270" }, - { 4, "reflect-x" }, - { 5, "reflect-y" }</td> - <td valign="top" >CRTC, Plane</td> - <td valign="top" >rotate-(degrees) rotates the image by the specified amount in degrees - in counter clockwise direction. reflect-x and reflect-y reflects the - image along the specified axis prior to rotation</td> - </tr> - <tr> - <td valign="top" >“scaling mode”</td> - <td valign="top" >ENUM</td> - <td valign="top" >{ "None", "Full", "Center", "Full aspect" }</td> - <td valign="top" >Connector</td> - <td valign="top" >Supported by: amdgpu, gma500, i915, nouveau and radeon.</td> - </tr> - <tr> - <td rowspan="5" valign="top" >Connector</td> - <td valign="top" >“EDID”</td> - <td valign="top" >BLOB | IMMUTABLE</td> - <td valign="top" >0</td> - <td valign="top" >Connector</td> - <td valign="top" >Contains id of edid blob ptr object.</td> - </tr> - <tr> - <td valign="top" >“DPMS”</td> - <td valign="top" >ENUM</td> - <td valign="top" >{ “On”, “Standby”, “Suspend”, “Off” }</td> - <td valign="top" >Connector</td> - <td valign="top" >Contains DPMS operation mode value.</td> - </tr> - <tr> - <td valign="top" >“PATH”</td> - <td valign="top" >BLOB | IMMUTABLE</td> - <td valign="top" >0</td> - <td valign="top" >Connector</td> - <td valign="top" >Contains topology path to a connector.</td> - </tr> - <tr> - <td valign="top" >“TILE”</td> - <td valign="top" >BLOB | IMMUTABLE</td> - <td valign="top" >0</td> - <td valign="top" >Connector</td> - <td valign="top" >Contains tiling information for a connector.</td> - </tr> - <tr> - <td valign="top" >“CRTC_ID”</td> - <td valign="top" >OBJECT</td> - <td valign="top" >DRM_MODE_OBJECT_CRTC</td> - <td valign="top" >Connector</td> - <td valign="top" >CRTC that connector is attached to (atomic)</td> - </tr> - <tr> - <td rowspan="11" valign="top" >Plane</td> - <td valign="top" >“type”</td> - <td valign="top" >ENUM | IMMUTABLE</td> - <td valign="top" >{ "Overlay", "Primary", "Cursor" }</td> - <td valign="top" >Plane</td> - <td valign="top" >Plane type</td> - </tr> - <tr> - <td valign="top" >“SRC_X”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=UINT_MAX</td> - <td valign="top" >Plane</td> - <td valign="top" >Scanout source x coordinate in 16.16 fixed point (atomic)</td> - </tr> - <tr> - <td valign="top" >“SRC_Y”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=UINT_MAX</td> - <td valign="top" >Plane</td> - <td valign="top" >Scanout source y coordinate in 16.16 fixed point (atomic)</td> - </tr> - <tr> - <td valign="top" >“SRC_W”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=UINT_MAX</td> - <td valign="top" >Plane</td> - <td valign="top" >Scanout source width in 16.16 fixed point (atomic)</td> - </tr> - <tr> - <td valign="top" >“SRC_H”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=UINT_MAX</td> - <td valign="top" >Plane</td> - <td valign="top" >Scanout source height in 16.16 fixed point (atomic)</td> - </tr> - <tr> - <td valign="top" >“CRTC_X”</td> - <td valign="top" >SIGNED_RANGE</td> - <td valign="top" >Min=INT_MIN, Max=INT_MAX</td> - <td valign="top" >Plane</td> - <td valign="top" >Scanout CRTC (destination) x coordinate (atomic)</td> - </tr> - <tr> - <td valign="top" >“CRTC_Y”</td> - <td valign="top" >SIGNED_RANGE</td> - <td valign="top" >Min=INT_MIN, Max=INT_MAX</td> - <td valign="top" >Plane</td> - <td valign="top" >Scanout CRTC (destination) y coordinate (atomic)</td> - </tr> - <tr> - <td valign="top" >“CRTC_W”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=UINT_MAX</td> - <td valign="top" >Plane</td> - <td valign="top" >Scanout CRTC (destination) width (atomic)</td> - </tr> - <tr> - <td valign="top" >“CRTC_H”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=UINT_MAX</td> - <td valign="top" >Plane</td> - <td valign="top" >Scanout CRTC (destination) height (atomic)</td> - </tr> - <tr> - <td valign="top" >“FB_ID”</td> - <td valign="top" >OBJECT</td> - <td valign="top" >DRM_MODE_OBJECT_FB</td> - <td valign="top" >Plane</td> - <td valign="top" >Scanout framebuffer (atomic)</td> - </tr> - <tr> - <td valign="top" >“CRTC_ID”</td> - <td valign="top" >OBJECT</td> - <td valign="top" >DRM_MODE_OBJECT_CRTC</td> - <td valign="top" >Plane</td> - <td valign="top" >CRTC that plane is attached to (atomic)</td> - </tr> - <tr> - <td rowspan="2" valign="top" >DVI-I</td> - <td valign="top" >“subconnector”</td> - <td valign="top" >ENUM</td> - <td valign="top" >{ “Unknown”, “DVI-D”, “DVI-A” }</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“select subconnector”</td> - <td valign="top" >ENUM</td> - <td valign="top" >{ “Automatic”, “DVI-D”, “DVI-A” }</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td rowspan="13" valign="top" >TV</td> - <td valign="top" >“subconnector”</td> - <td valign="top" >ENUM</td> - <td valign="top" >{ "Unknown", "Composite", "SVIDEO", "Component", "SCART" }</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“select subconnector”</td> - <td valign="top" >ENUM</td> - <td valign="top" >{ "Automatic", "Composite", "SVIDEO", "Component", "SCART" }</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“mode”</td> - <td valign="top" >ENUM</td> - <td valign="top" >{ "NTSC_M", "NTSC_J", "NTSC_443", "PAL_B" } etc.</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“left margin”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=100</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“right margin”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=100</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“top margin”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=100</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“bottom margin”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=100</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“brightness”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=100</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“contrast”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=100</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“flicker reduction”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=100</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“overscan”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=100</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“saturation”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=100</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“hue”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=100</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td rowspan="2" valign="top" >Virtual GPU</td> - <td valign="top" >“suggested X”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=0xffffffff</td> - <td valign="top" >Connector</td> - <td valign="top" >property to suggest an X offset for a connector</td> - </tr> - <tr> - <td valign="top" >“suggested Y”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=0xffffffff</td> - <td valign="top" >Connector</td> - <td valign="top" >property to suggest an Y offset for a connector</td> - </tr> - <tr> - <td rowspan="7" valign="top" >Optional</td> - <td valign="top" >"aspect ratio"</td> - <td valign="top" >ENUM</td> - <td valign="top" >{ "None", "4:3", "16:9" }</td> - <td valign="top" >Connector</td> - <td valign="top" >TDB</td> - </tr> - <tr> - <td valign="top" >“dirty”</td> - <td valign="top" >ENUM | IMMUTABLE</td> - <td valign="top" >{ "Off", "On", "Annotate" }</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“DEGAMMA_LUT”</td> - <td valign="top" >BLOB</td> - <td valign="top" >0</td> - <td valign="top" >CRTC</td> - <td valign="top" >DRM property to set the degamma lookup table - (LUT) mapping pixel data from the framebuffer before it is - given to the transformation matrix. The data is an interpreted - as an array of struct drm_color_lut elements. Hardware might - choose not to use the full precision of the LUT elements nor - use all the elements of the LUT (for example the hardware - might choose to interpolate between LUT[0] and LUT[4]). </td> - </tr> - <tr> - <td valign="top" >“DEGAMMA_LUT_SIZE”</td> - <td valign="top" >RANGE | IMMUTABLE</td> - <td valign="top" >Min=0, Max=UINT_MAX</td> - <td valign="top" >CRTC</td> - <td valign="top" >DRM property to gives the size of the lookup - table to be set on the DEGAMMA_LUT property (the size depends - on the underlying hardware).</td> - </tr> - <tr> - <td valign="top" >“CTM”</td> - <td valign="top" >BLOB</td> - <td valign="top" >0</td> - <td valign="top" >CRTC</td> - <td valign="top" >DRM property to set the current - transformation matrix (CTM) apply to pixel data after the - lookup through the degamma LUT and before the lookup through - the gamma LUT. The data is an interpreted as a struct - drm_color_ctm.</td> - </tr> - <tr> - <td valign="top" >“GAMMA_LUT”</td> - <td valign="top" >BLOB</td> - <td valign="top" >0</td> - <td valign="top" >CRTC</td> - <td valign="top" >DRM property to set the gamma lookup table - (LUT) mapping pixel data after to the transformation matrix to - data sent to the connector. The data is an interpreted as an - array of struct drm_color_lut elements. Hardware might choose - not to use the full precision of the LUT elements nor use all - the elements of the LUT (for example the hardware might choose - to interpolate between LUT[0] and LUT[4]).</td> - </tr> - <tr> - <td valign="top" >“GAMMA_LUT_SIZE”</td> - <td valign="top" >RANGE | IMMUTABLE</td> - <td valign="top" >Min=0, Max=UINT_MAX</td> - <td valign="top" >CRTC</td> - <td valign="top" >DRM property to gives the size of the lookup - table to be set on the GAMMA_LUT property (the size depends on - the underlying hardware).</td> - </tr> - <tr> - <td rowspan="20" valign="top" >i915</td> - <td rowspan="2" valign="top" >Generic</td> - <td valign="top" >"Broadcast RGB"</td> - <td valign="top" >ENUM</td> - <td valign="top" >{ "Automatic", "Full", "Limited 16:235" }</td> - <td valign="top" >Connector</td> - <td valign="top" >When this property is set to Limited 16:235 - and CTM is set, the hardware will be programmed with the - result of the multiplication of CTM by the limited range - matrix to ensure the pixels normaly in the range 0..1.0 are - remapped to the range 16/255..235/255.</td> - </tr> - <tr> - <td valign="top" >“audio”</td> - <td valign="top" >ENUM</td> - <td valign="top" >{ "force-dvi", "off", "auto", "on" }</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td rowspan="17" valign="top" >SDVO-TV</td> - <td valign="top" >“mode”</td> - <td valign="top" >ENUM</td> - <td valign="top" >{ "NTSC_M", "NTSC_J", "NTSC_443", "PAL_B" } etc.</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >"left_margin"</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max= SDVO dependent</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >"right_margin"</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max= SDVO dependent</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >"top_margin"</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max= SDVO dependent</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >"bottom_margin"</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max= SDVO dependent</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“hpos”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max= SDVO dependent</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“vpos”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max= SDVO dependent</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“contrast”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max= SDVO dependent</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“saturation”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max= SDVO dependent</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“hue”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max= SDVO dependent</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“sharpness”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max= SDVO dependent</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“flicker_filter”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max= SDVO dependent</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“flicker_filter_adaptive”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max= SDVO dependent</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“flicker_filter_2d”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max= SDVO dependent</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“tv_chroma_filter”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max= SDVO dependent</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“tv_luma_filter”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max= SDVO dependent</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“dot_crawl”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=1</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >SDVO-TV/LVDS</td> - <td valign="top" >“brightness”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max= SDVO dependent</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td rowspan="2" valign="top" >CDV gma-500</td> - <td rowspan="2" valign="top" >Generic</td> - <td valign="top" >"Broadcast RGB"</td> - <td valign="top" >ENUM</td> - <td valign="top" >{ “Full”, “Limited 16:235” }</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >"Broadcast RGB"</td> - <td valign="top" >ENUM</td> - <td valign="top" >{ “off”, “auto”, “on” }</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td rowspan="19" valign="top" >Poulsbo</td> - <td rowspan="1" valign="top" >Generic</td> - <td valign="top" >“backlight”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=100</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td rowspan="17" valign="top" >SDVO-TV</td> - <td valign="top" >“mode”</td> - <td valign="top" >ENUM</td> - <td valign="top" >{ "NTSC_M", "NTSC_J", "NTSC_443", "PAL_B" } etc.</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >"left_margin"</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max= SDVO dependent</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >"right_margin"</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max= SDVO dependent</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >"top_margin"</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max= SDVO dependent</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >"bottom_margin"</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max= SDVO dependent</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“hpos”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max= SDVO dependent</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“vpos”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max= SDVO dependent</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“contrast”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max= SDVO dependent</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“saturation”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max= SDVO dependent</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“hue”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max= SDVO dependent</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“sharpness”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max= SDVO dependent</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“flicker_filter”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max= SDVO dependent</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“flicker_filter_adaptive”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max= SDVO dependent</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“flicker_filter_2d”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max= SDVO dependent</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“tv_chroma_filter”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max= SDVO dependent</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“tv_luma_filter”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max= SDVO dependent</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“dot_crawl”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=1</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >SDVO-TV/LVDS</td> - <td valign="top" >“brightness”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max= SDVO dependent</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td rowspan="11" valign="top" >armada</td> - <td rowspan="2" valign="top" >CRTC</td> - <td valign="top" >"CSC_YUV"</td> - <td valign="top" >ENUM</td> - <td valign="top" >{ "Auto" , "CCIR601", "CCIR709" }</td> - <td valign="top" >CRTC</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >"CSC_RGB"</td> - <td valign="top" >ENUM</td> - <td valign="top" >{ "Auto", "Computer system", "Studio" }</td> - <td valign="top" >CRTC</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td rowspan="9" valign="top" >Overlay</td> - <td valign="top" >"colorkey"</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=0xffffff</td> - <td valign="top" >Plane</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >"colorkey_min"</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=0xffffff</td> - <td valign="top" >Plane</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >"colorkey_max"</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=0xffffff</td> - <td valign="top" >Plane</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >"colorkey_val"</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=0xffffff</td> - <td valign="top" >Plane</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >"colorkey_alpha"</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=0xffffff</td> - <td valign="top" >Plane</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >"colorkey_mode"</td> - <td valign="top" >ENUM</td> - <td valign="top" >{ "disabled", "Y component", "U component" - , "V component", "RGB", “R component", "G component", "B component" }</td> - <td valign="top" >Plane</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >"brightness"</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=256 + 255</td> - <td valign="top" >Plane</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >"contrast"</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=0x7fff</td> - <td valign="top" >Plane</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >"saturation"</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=0x7fff</td> - <td valign="top" >Plane</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td rowspan="2" valign="top" >exynos</td> - <td valign="top" >CRTC</td> - <td valign="top" >“mode”</td> - <td valign="top" >ENUM</td> - <td valign="top" >{ "normal", "blank" }</td> - <td valign="top" >CRTC</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >Overlay</td> - <td valign="top" >“zpos”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=MAX_PLANE-1</td> - <td valign="top" >Plane</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td rowspan="2" valign="top" >i2c/ch7006_drv</td> - <td valign="top" >Generic</td> - <td valign="top" >“scale”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=2</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td rowspan="1" valign="top" >TV</td> - <td valign="top" >“mode”</td> - <td valign="top" >ENUM</td> - <td valign="top" >{ "PAL", "PAL-M","PAL-N"}, ”PAL-Nc" - , "PAL-60", "NTSC-M", "NTSC-J" }</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td rowspan="15" valign="top" >nouveau</td> - <td rowspan="6" valign="top" >NV10 Overlay</td> - <td valign="top" >"colorkey"</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=0x01ffffff</td> - <td valign="top" >Plane</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“contrast”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=8192-1</td> - <td valign="top" >Plane</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“brightness”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=1024</td> - <td valign="top" >Plane</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“hue”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=359</td> - <td valign="top" >Plane</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“saturation”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=8192-1</td> - <td valign="top" >Plane</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“iturbt_709”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=1</td> - <td valign="top" >Plane</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td rowspan="2" valign="top" >Nv04 Overlay</td> - <td valign="top" >“colorkey”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=0x01ffffff</td> - <td valign="top" >Plane</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“brightness”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=1024</td> - <td valign="top" >Plane</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td rowspan="7" valign="top" >Display</td> - <td valign="top" >“dithering mode”</td> - <td valign="top" >ENUM</td> - <td valign="top" >{ "auto", "off", "on" }</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“dithering depth”</td> - <td valign="top" >ENUM</td> - <td valign="top" >{ "auto", "off", "on", "static 2x2", "dynamic 2x2", "temporal" }</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“underscan”</td> - <td valign="top" >ENUM</td> - <td valign="top" >{ "auto", "6 bpc", "8 bpc" }</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“underscan hborder”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=128</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“underscan vborder”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=128</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“vibrant hue”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=180</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“color vibrance”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=200</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >omap</td> - <td valign="top" >Generic</td> - <td valign="top" >“zorder”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=3</td> - <td valign="top" >CRTC, Plane</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >qxl</td> - <td valign="top" >Generic</td> - <td valign="top" >“hotplug_mode_update"</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=1</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td rowspan="9" valign="top" >radeon</td> - <td valign="top" >DVI-I</td> - <td valign="top" >“coherent”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=1</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >DAC enable load detect</td> - <td valign="top" >“load detection”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=1</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >TV Standard</td> - <td valign="top" >"tv standard"</td> - <td valign="top" >ENUM</td> - <td valign="top" >{ "ntsc", "pal", "pal-m", "pal-60", "ntsc-j" - , "scart-pal", "pal-cn", "secam" }</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >legacy TMDS PLL detect</td> - <td valign="top" >"tmds_pll"</td> - <td valign="top" >ENUM</td> - <td valign="top" >{ "driver", "bios" }</td> - <td valign="top" >-</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td rowspan="3" valign="top" >Underscan</td> - <td valign="top" >"underscan"</td> - <td valign="top" >ENUM</td> - <td valign="top" >{ "off", "on", "auto" }</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >"underscan hborder"</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=128</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >"underscan vborder"</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=128</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >Audio</td> - <td valign="top" >“audio”</td> - <td valign="top" >ENUM</td> - <td valign="top" >{ "off", "on", "auto" }</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >FMT Dithering</td> - <td valign="top" >“dither”</td> - <td valign="top" >ENUM</td> - <td valign="top" >{ "off", "on" }</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td rowspan="3" valign="top" >rcar-du</td> - <td rowspan="3" valign="top" >Generic</td> - <td valign="top" >"alpha"</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=255</td> - <td valign="top" >Plane</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >"colorkey"</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=0x01ffffff</td> - <td valign="top" >Plane</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >"zpos"</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=1, Max=7</td> - <td valign="top" >Plane</td> - <td valign="top" >TBD</td> - </tr> - </tbody> - </table> - </sect2> - </sect1> - - <!-- Internals: vertical blanking --> - - <sect1 id="drm-vertical-blank"> - <title>Vertical Blanking</title> - <para> - Vertical blanking plays a major role in graphics rendering. To achieve - tear-free display, users must synchronize page flips and/or rendering to - vertical blanking. The DRM API offers ioctls to perform page flips - synchronized to vertical blanking and wait for vertical blanking. - </para> - <para> - The DRM core handles most of the vertical blanking management logic, which - involves filtering out spurious interrupts, keeping race-free blanking - counters, coping with counter wrap-around and resets and keeping use - counts. It relies on the driver to generate vertical blanking interrupts - and optionally provide a hardware vertical blanking counter. Drivers must - implement the following operations. - </para> - <itemizedlist> - <listitem> - <synopsis>int (*enable_vblank) (struct drm_device *dev, int crtc); -void (*disable_vblank) (struct drm_device *dev, int crtc);</synopsis> - <para> - Enable or disable vertical blanking interrupts for the given CRTC. - </para> - </listitem> - <listitem> - <synopsis>u32 (*get_vblank_counter) (struct drm_device *dev, int crtc);</synopsis> - <para> - Retrieve the value of the vertical blanking counter for the given - CRTC. If the hardware maintains a vertical blanking counter its value - should be returned. Otherwise drivers can use the - <function>drm_vblank_count</function> helper function to handle this - operation. - </para> - </listitem> - </itemizedlist> - <para> - Drivers must initialize the vertical blanking handling core with a call to - <function>drm_vblank_init</function> in their - <methodname>load</methodname> operation. The function will set the struct - <structname>drm_device</structname> - <structfield>vblank_disable_allowed</structfield> field to 0. This will - keep vertical blanking interrupts enabled permanently until the first mode - set operation, where <structfield>vblank_disable_allowed</structfield> is - set to 1. The reason behind this is not clear. Drivers can set the field - to 1 after <function>calling drm_vblank_init</function> to make vertical - blanking interrupts dynamically managed from the beginning. - </para> - <para> - Vertical blanking interrupts can be enabled by the DRM core or by drivers - themselves (for instance to handle page flipping operations). The DRM core - maintains a vertical blanking use count to ensure that the interrupts are - not disabled while a user still needs them. To increment the use count, - drivers call <function>drm_vblank_get</function>. Upon return vertical - blanking interrupts are guaranteed to be enabled. - </para> - <para> - To decrement the use count drivers call - <function>drm_vblank_put</function>. Only when the use count drops to zero - will the DRM core disable the vertical blanking interrupts after a delay - by scheduling a timer. The delay is accessible through the vblankoffdelay - module parameter or the <varname>drm_vblank_offdelay</varname> global - variable and expressed in milliseconds. Its default value is 5000 ms. - Zero means never disable, and a negative value means disable immediately. - Drivers may override the behaviour by setting the - <structname>drm_device</structname> - <structfield>vblank_disable_immediate</structfield> flag, which when set - causes vblank interrupts to be disabled immediately regardless of the - drm_vblank_offdelay value. The flag should only be set if there's a - properly working hardware vblank counter present. - </para> - <para> - When a vertical blanking interrupt occurs drivers only need to call the - <function>drm_handle_vblank</function> function to account for the - interrupt. - </para> - <para> - Resources allocated by <function>drm_vblank_init</function> must be freed - with a call to <function>drm_vblank_cleanup</function> in the driver - <methodname>unload</methodname> operation handler. - </para> - <sect2> - <title>Vertical Blanking and Interrupt Handling Functions Reference</title> -!Edrivers/gpu/drm/drm_irq.c -!Finclude/drm/drmP.h drm_crtc_vblank_waitqueue - </sect2> - </sect1> - - <!-- Internals: open/close, file operations and ioctls --> - - <sect1> - <title>Open/Close, File Operations and IOCTLs</title> - <sect2> - <title>Open and Close</title> - <synopsis>int (*firstopen) (struct drm_device *); -void (*lastclose) (struct drm_device *); -int (*open) (struct drm_device *, struct drm_file *); -void (*preclose) (struct drm_device *, struct drm_file *); -void (*postclose) (struct drm_device *, struct drm_file *);</synopsis> - <abstract>Open and close handlers. None of those methods are mandatory. - </abstract> - <para> - The <methodname>firstopen</methodname> method is called by the DRM core - for legacy UMS (User Mode Setting) drivers only when an application - opens a device that has no other opened file handle. UMS drivers can - implement it to acquire device resources. KMS drivers can't use the - method and must acquire resources in the <methodname>load</methodname> - method instead. - </para> - <para> - Similarly the <methodname>lastclose</methodname> method is called when - the last application holding a file handle opened on the device closes - it, for both UMS and KMS drivers. Additionally, the method is also - called at module unload time or, for hot-pluggable devices, when the - device is unplugged. The <methodname>firstopen</methodname> and - <methodname>lastclose</methodname> calls can thus be unbalanced. - </para> - <para> - The <methodname>open</methodname> method is called every time the device - is opened by an application. Drivers can allocate per-file private data - in this method and store them in the struct - <structname>drm_file</structname> <structfield>driver_priv</structfield> - field. Note that the <methodname>open</methodname> method is called - before <methodname>firstopen</methodname>. - </para> - <para> - The close operation is split into <methodname>preclose</methodname> and - <methodname>postclose</methodname> methods. Drivers must stop and - cleanup all per-file operations in the <methodname>preclose</methodname> - method. For instance pending vertical blanking and page flip events must - be cancelled. No per-file operation is allowed on the file handle after - returning from the <methodname>preclose</methodname> method. - </para> - <para> - Finally the <methodname>postclose</methodname> method is called as the - last step of the close operation, right before calling the - <methodname>lastclose</methodname> method if no other open file handle - exists for the device. Drivers that have allocated per-file private data - in the <methodname>open</methodname> method should free it here. - </para> - <para> - The <methodname>lastclose</methodname> method should restore CRTC and - plane properties to default value, so that a subsequent open of the - device will not inherit state from the previous user. It can also be - used to execute delayed power switching state changes, e.g. in - conjunction with the vga_switcheroo infrastructure (see - <xref linkend="vga_switcheroo"/>). Beyond that KMS drivers should not - do any further cleanup. Only legacy UMS drivers might need to clean up - device state so that the vga console or an independent fbdev driver - could take over. - </para> - </sect2> - <sect2> - <title>File Operations</title> -!Pdrivers/gpu/drm/drm_fops.c file operations -!Edrivers/gpu/drm/drm_fops.c - </sect2> - <sect2> - <title>IOCTLs</title> - <synopsis>struct drm_ioctl_desc *ioctls; -int num_ioctls;</synopsis> - <abstract>Driver-specific ioctls descriptors table.</abstract> - <para> - Driver-specific ioctls numbers start at DRM_COMMAND_BASE. The ioctls - descriptors table is indexed by the ioctl number offset from the base - value. Drivers can use the DRM_IOCTL_DEF_DRV() macro to initialize the - table entries. - </para> - <para> - <programlisting>DRM_IOCTL_DEF_DRV(ioctl, func, flags)</programlisting> - <para> - <parameter>ioctl</parameter> is the ioctl name. Drivers must define - the DRM_##ioctl and DRM_IOCTL_##ioctl macros to the ioctl number - offset from DRM_COMMAND_BASE and the ioctl number respectively. The - first macro is private to the device while the second must be exposed - to userspace in a public header. - </para> - <para> - <parameter>func</parameter> is a pointer to the ioctl handler function - compatible with the <type>drm_ioctl_t</type> type. - <programlisting>typedef int drm_ioctl_t(struct drm_device *dev, void *data, - struct drm_file *file_priv);</programlisting> - </para> - <para> - <parameter>flags</parameter> is a bitmask combination of the following - values. It restricts how the ioctl is allowed to be called. - <itemizedlist> - <listitem><para> - DRM_AUTH - Only authenticated callers allowed - </para></listitem> - <listitem><para> - DRM_MASTER - The ioctl can only be called on the master file - handle - </para></listitem> - <listitem><para> - DRM_ROOT_ONLY - Only callers with the SYSADMIN capability allowed - </para></listitem> - <listitem><para> - DRM_CONTROL_ALLOW - The ioctl can only be called on a control - device - </para></listitem> - <listitem><para> - DRM_UNLOCKED - The ioctl handler will be called without locking - the DRM global mutex. This is the enforced default for kms drivers - (i.e. using the DRIVER_MODESET flag) and hence shouldn't be used - any more for new drivers. - </para></listitem> - </itemizedlist> - </para> - </para> -!Edrivers/gpu/drm/drm_ioctl.c - </sect2> - </sect1> - <sect1> - <title>Legacy Support Code</title> - <para> - The section very briefly covers some of the old legacy support code which - is only used by old DRM drivers which have done a so-called shadow-attach - to the underlying device instead of registering as a real driver. This - also includes some of the old generic buffer management and command - submission code. Do not use any of this in new and modern drivers. - </para> - - <sect2> - <title>Legacy Suspend/Resume</title> - <para> - The DRM core provides some suspend/resume code, but drivers wanting full - suspend/resume support should provide save() and restore() functions. - These are called at suspend, hibernate, or resume time, and should perform - any state save or restore required by your device across suspend or - hibernate states. - </para> - <synopsis>int (*suspend) (struct drm_device *, pm_message_t state); - int (*resume) (struct drm_device *);</synopsis> - <para> - Those are legacy suspend and resume methods which - <emphasis>only</emphasis> work with the legacy shadow-attach driver - registration functions. New driver should use the power management - interface provided by their bus type (usually through - the struct <structname>device_driver</structname> dev_pm_ops) and set - these methods to NULL. - </para> - </sect2> - - <sect2> - <title>Legacy DMA Services</title> - <para> - This should cover how DMA mapping etc. is supported by the core. - These functions are deprecated and should not be used. - </para> - </sect2> - </sect1> - </chapter> - -<!-- TODO - -- Add a glossary -- Document the struct_mutex catch-all lock -- Document connector properties - -- Why is the load method optional? -- What are drivers supposed to set the initial display state to, and how? - Connector's DPMS states are not initialized and are thus equal to - DRM_MODE_DPMS_ON. The fbcon compatibility layer calls - drm_helper_disable_unused_functions(), which disables unused encoders and - CRTCs, but doesn't touch the connectors' DPMS state, and - drm_helper_connector_dpms() in reaction to fbdev blanking events. Do drivers - that don't implement (or just don't use) fbcon compatibility need to call - those functions themselves? -- KMS drivers must call drm_vblank_pre_modeset() and drm_vblank_post_modeset() - around mode setting. Should this be done in the DRM core? -- vblank_disable_allowed is set to 1 in the first drm_vblank_post_modeset() - call and never set back to 0. It seems to be safe to permanently set it to 1 - in drm_vblank_init() for KMS driver, and it might be safe for UMS drivers as - well. This should be investigated. -- crtc and connector .save and .restore operations are only used internally in - drivers, should they be removed from the core? -- encoder mid-layer .save and .restore operations are only used internally in - drivers, should they be removed from the core? -- encoder mid-layer .detect operation is only used internally in drivers, - should it be removed from the core? ---> - - <!-- External interfaces --> - - <chapter id="drmExternals"> - <title>Userland interfaces</title> - <para> - The DRM core exports several interfaces to applications, - generally intended to be used through corresponding libdrm - wrapper functions. In addition, drivers export device-specific - interfaces for use by userspace drivers & device-aware - applications through ioctls and sysfs files. - </para> - <para> - External interfaces include: memory mapping, context management, - DMA operations, AGP management, vblank control, fence - management, memory management, and output management. - </para> - <para> - Cover generic ioctls and sysfs layout here. We only need high-level - info, since man pages should cover the rest. - </para> - - <!-- External: render nodes --> - - <sect1> - <title>Render nodes</title> - <para> - DRM core provides multiple character-devices for user-space to use. - Depending on which device is opened, user-space can perform a different - set of operations (mainly ioctls). The primary node is always created - and called card<num>. Additionally, a currently - unused control node, called controlD<num> is also - created. The primary node provides all legacy operations and - historically was the only interface used by userspace. With KMS, the - control node was introduced. However, the planned KMS control interface - has never been written and so the control node stays unused to date. - </para> - <para> - With the increased use of offscreen renderers and GPGPU applications, - clients no longer require running compositors or graphics servers to - make use of a GPU. But the DRM API required unprivileged clients to - authenticate to a DRM-Master prior to getting GPU access. To avoid this - step and to grant clients GPU access without authenticating, render - nodes were introduced. Render nodes solely serve render clients, that - is, no modesetting or privileged ioctls can be issued on render nodes. - Only non-global rendering commands are allowed. If a driver supports - render nodes, it must advertise it via the DRIVER_RENDER - DRM driver capability. If not supported, the primary node must be used - for render clients together with the legacy drmAuth authentication - procedure. - </para> - <para> - If a driver advertises render node support, DRM core will create a - separate render node called renderD<num>. There will - be one render node per device. No ioctls except PRIME-related ioctls - will be allowed on this node. Especially GEM_OPEN will be - explicitly prohibited. Render nodes are designed to avoid the - buffer-leaks, which occur if clients guess the flink names or mmap - offsets on the legacy interface. Additionally to this basic interface, - drivers must mark their driver-dependent render-only ioctls as - DRM_RENDER_ALLOW so render clients can use them. Driver - authors must be careful not to allow any privileged ioctls on render - nodes. - </para> - <para> - With render nodes, user-space can now control access to the render node - via basic file-system access-modes. A running graphics server which - authenticates clients on the privileged primary/legacy node is no longer - required. Instead, a client can open the render node and is immediately - granted GPU access. Communication between clients (or servers) is done - via PRIME. FLINK from render node to legacy node is not supported. New - clients must not use the insecure FLINK interface. - </para> - <para> - Besides dropping all modeset/global ioctls, render nodes also drop the - DRM-Master concept. There is no reason to associate render clients with - a DRM-Master as they are independent of any graphics server. Besides, - they must work without any running master, anyway. - Drivers must be able to run without a master object if they support - render nodes. If, on the other hand, a driver requires shared state - between clients which is visible to user-space and accessible beyond - open-file boundaries, they cannot support render nodes. - </para> - </sect1> - - <!-- External: vblank handling --> - - <sect1> - <title>VBlank event handling</title> - <para> - The DRM core exposes two vertical blank related ioctls: - <variablelist> - <varlistentry> - <term>DRM_IOCTL_WAIT_VBLANK</term> - <listitem> - <para> - This takes a struct drm_wait_vblank structure as its argument, - and it is used to block or request a signal when a specified - vblank event occurs. - </para> - </listitem> - </varlistentry> - <varlistentry> - <term>DRM_IOCTL_MODESET_CTL</term> - <listitem> - <para> - This was only used for user-mode-settind drivers around - modesetting changes to allow the kernel to update the vblank - interrupt after mode setting, since on many devices the vertical - blank counter is reset to 0 at some point during modeset. Modern - drivers should not call this any more since with kernel mode - setting it is a no-op. - </para> - </listitem> - </varlistentry> - </variablelist> - </para> - </sect1> - - </chapter> -</part> -<part id="drmDrivers"> - <title>DRM Drivers</title> - - <partintro> - <para> - This second part of the GPU Driver Developer's Guide documents driver - code, implementation details and also all the driver-specific userspace - interfaces. Especially since all hardware-acceleration interfaces to - userspace are driver specific for efficiency and other reasons these - interfaces can be rather substantial. Hence every driver has its own - chapter. - </para> - </partintro> - - <chapter id="drmI915"> - <title>drm/i915 Intel GFX Driver</title> - <para> - The drm/i915 driver supports all (with the exception of some very early - models) integrated GFX chipsets with both Intel display and rendering - blocks. This excludes a set of SoC platforms with an SGX rendering unit, - those have basic support through the gma500 drm driver. - </para> - <sect1> - <title>Core Driver Infrastructure</title> - <para> - This section covers core driver infrastructure used by both the display - and the GEM parts of the driver. - </para> - <sect2> - <title>Runtime Power Management</title> -!Pdrivers/gpu/drm/i915/intel_runtime_pm.c runtime pm -!Idrivers/gpu/drm/i915/intel_runtime_pm.c -!Idrivers/gpu/drm/i915/intel_uncore.c - </sect2> - <sect2> - <title>Interrupt Handling</title> -!Pdrivers/gpu/drm/i915/i915_irq.c interrupt handling -!Fdrivers/gpu/drm/i915/i915_irq.c intel_irq_init intel_irq_init_hw intel_hpd_init -!Fdrivers/gpu/drm/i915/i915_irq.c intel_runtime_pm_disable_interrupts -!Fdrivers/gpu/drm/i915/i915_irq.c intel_runtime_pm_enable_interrupts - </sect2> - <sect2> - <title>Intel GVT-g Guest Support(vGPU)</title> -!Pdrivers/gpu/drm/i915/i915_vgpu.c Intel GVT-g guest support -!Idrivers/gpu/drm/i915/i915_vgpu.c - </sect2> - </sect1> - <sect1> - <title>Display Hardware Handling</title> - <para> - This section covers everything related to the display hardware including - the mode setting infrastructure, plane, sprite and cursor handling and - display, output probing and related topics. - </para> - <sect2> - <title>Mode Setting Infrastructure</title> - <para> - The i915 driver is thus far the only DRM driver which doesn't use the - common DRM helper code to implement mode setting sequences. Thus it - has its own tailor-made infrastructure for executing a display - configuration change. - </para> - </sect2> - <sect2> - <title>Frontbuffer Tracking</title> -!Pdrivers/gpu/drm/i915/intel_frontbuffer.c frontbuffer tracking -!Idrivers/gpu/drm/i915/intel_frontbuffer.c -!Fdrivers/gpu/drm/i915/i915_gem.c i915_gem_track_fb - </sect2> - <sect2> - <title>Display FIFO Underrun Reporting</title> -!Pdrivers/gpu/drm/i915/intel_fifo_underrun.c fifo underrun handling -!Idrivers/gpu/drm/i915/intel_fifo_underrun.c - </sect2> - <sect2> - <title>Plane Configuration</title> - <para> - This section covers plane configuration and composition with the - primary plane, sprites, cursors and overlays. This includes the - infrastructure to do atomic vsync'ed updates of all this state and - also tightly coupled topics like watermark setup and computation, - framebuffer compression and panel self refresh. - </para> - </sect2> - <sect2> - <title>Atomic Plane Helpers</title> -!Pdrivers/gpu/drm/i915/intel_atomic_plane.c atomic plane helpers -!Idrivers/gpu/drm/i915/intel_atomic_plane.c - </sect2> - <sect2> - <title>Output Probing</title> - <para> - This section covers output probing and related infrastructure like the - hotplug interrupt storm detection and mitigation code. Note that the - i915 driver still uses most of the common DRM helper code for output - probing, so those sections fully apply. - </para> - </sect2> - <sect2> - <title>Hotplug</title> -!Pdrivers/gpu/drm/i915/intel_hotplug.c Hotplug -!Idrivers/gpu/drm/i915/intel_hotplug.c - </sect2> - <sect2> - <title>High Definition Audio</title> -!Pdrivers/gpu/drm/i915/intel_audio.c High Definition Audio over HDMI and Display Port -!Idrivers/gpu/drm/i915/intel_audio.c -!Iinclude/drm/i915_component.h - </sect2> - <sect2> - <title>Panel Self Refresh PSR (PSR/SRD)</title> -!Pdrivers/gpu/drm/i915/intel_psr.c Panel Self Refresh (PSR/SRD) -!Idrivers/gpu/drm/i915/intel_psr.c - </sect2> - <sect2> - <title>Frame Buffer Compression (FBC)</title> -!Pdrivers/gpu/drm/i915/intel_fbc.c Frame Buffer Compression (FBC) -!Idrivers/gpu/drm/i915/intel_fbc.c - </sect2> - <sect2> - <title>Display Refresh Rate Switching (DRRS)</title> -!Pdrivers/gpu/drm/i915/intel_dp.c Display Refresh Rate Switching (DRRS) -!Fdrivers/gpu/drm/i915/intel_dp.c intel_dp_set_drrs_state -!Fdrivers/gpu/drm/i915/intel_dp.c intel_edp_drrs_enable -!Fdrivers/gpu/drm/i915/intel_dp.c intel_edp_drrs_disable -!Fdrivers/gpu/drm/i915/intel_dp.c intel_edp_drrs_invalidate -!Fdrivers/gpu/drm/i915/intel_dp.c intel_edp_drrs_flush -!Fdrivers/gpu/drm/i915/intel_dp.c intel_dp_drrs_init - - </sect2> - <sect2> - <title>DPIO</title> -!Pdrivers/gpu/drm/i915/i915_reg.h DPIO - </sect2> - - <sect2> - <title>CSR firmware support for DMC</title> -!Pdrivers/gpu/drm/i915/intel_csr.c csr support for dmc -!Idrivers/gpu/drm/i915/intel_csr.c - </sect2> - <sect2> - <title>Video BIOS Table (VBT)</title> -!Pdrivers/gpu/drm/i915/intel_bios.c Video BIOS Table (VBT) -!Idrivers/gpu/drm/i915/intel_bios.c -!Idrivers/gpu/drm/i915/intel_vbt_defs.h - </sect2> - </sect1> - - <sect1> - <title>Memory Management and Command Submission</title> - <para> - This sections covers all things related to the GEM implementation in the - i915 driver. - </para> - <sect2> - <title>Batchbuffer Parsing</title> -!Pdrivers/gpu/drm/i915/i915_cmd_parser.c batch buffer command parser -!Idrivers/gpu/drm/i915/i915_cmd_parser.c - </sect2> - <sect2> - <title>Batchbuffer Pools</title> -!Pdrivers/gpu/drm/i915/i915_gem_batch_pool.c batch pool -!Idrivers/gpu/drm/i915/i915_gem_batch_pool.c - </sect2> - <sect2> - <title>Logical Rings, Logical Ring Contexts and Execlists</title> -!Pdrivers/gpu/drm/i915/intel_lrc.c Logical Rings, Logical Ring Contexts and Execlists -!Idrivers/gpu/drm/i915/intel_lrc.c - </sect2> - <sect2> - <title>Global GTT views</title> -!Pdrivers/gpu/drm/i915/i915_gem_gtt.c Global GTT views -!Idrivers/gpu/drm/i915/i915_gem_gtt.c - </sect2> - <sect2> - <title>GTT Fences and Swizzling</title> -!Idrivers/gpu/drm/i915/i915_gem_fence.c - <sect3> - <title>Global GTT Fence Handling</title> -!Pdrivers/gpu/drm/i915/i915_gem_fence.c fence register handling - </sect3> - <sect3> - <title>Hardware Tiling and Swizzling Details</title> -!Pdrivers/gpu/drm/i915/i915_gem_fence.c tiling swizzling details - </sect3> - </sect2> - <sect2> - <title>Object Tiling IOCTLs</title> -!Idrivers/gpu/drm/i915/i915_gem_tiling.c -!Pdrivers/gpu/drm/i915/i915_gem_tiling.c buffer object tiling - </sect2> - <sect2> - <title>Buffer Object Eviction</title> - <para> - This section documents the interface functions for evicting buffer - objects to make space available in the virtual gpu address spaces. - Note that this is mostly orthogonal to shrinking buffer objects - caches, which has the goal to make main memory (shared with the gpu - through the unified memory architecture) available. - </para> -!Idrivers/gpu/drm/i915/i915_gem_evict.c - </sect2> - <sect2> - <title>Buffer Object Memory Shrinking</title> - <para> - This section documents the interface function for shrinking memory - usage of buffer object caches. Shrinking is used to make main memory - available. Note that this is mostly orthogonal to evicting buffer - objects, which has the goal to make space in gpu virtual address - spaces. - </para> -!Idrivers/gpu/drm/i915/i915_gem_shrinker.c - </sect2> - </sect1> - <sect1> - <title>GuC</title> - <sect2> - <title>GuC-specific firmware loader</title> -!Pdrivers/gpu/drm/i915/intel_guc_loader.c GuC-specific firmware loader -!Idrivers/gpu/drm/i915/intel_guc_loader.c - </sect2> - <sect2> - <title>GuC-based command submission</title> -!Pdrivers/gpu/drm/i915/i915_guc_submission.c GuC-based command submission -!Idrivers/gpu/drm/i915/i915_guc_submission.c - </sect2> - <sect2> - <title>GuC Firmware Layout</title> -!Pdrivers/gpu/drm/i915/intel_guc_fwif.h GuC Firmware Layout - </sect2> - </sect1> - - <sect1> - <title> Tracing </title> - <para> - This sections covers all things related to the tracepoints implemented in - the i915 driver. - </para> - <sect2> - <title> i915_ppgtt_create and i915_ppgtt_release </title> -!Pdrivers/gpu/drm/i915/i915_trace.h i915_ppgtt_create and i915_ppgtt_release tracepoints - </sect2> - <sect2> - <title> i915_context_create and i915_context_free </title> -!Pdrivers/gpu/drm/i915/i915_trace.h i915_context_create and i915_context_free tracepoints - </sect2> - <sect2> - <title> switch_mm </title> -!Pdrivers/gpu/drm/i915/i915_trace.h switch_mm tracepoint - </sect2> - </sect1> - - </chapter> -!Cdrivers/gpu/drm/i915/i915_irq.c -</part> - -<part id="vga_switcheroo"> - <title>vga_switcheroo</title> - <partintro> -!Pdrivers/gpu/vga/vga_switcheroo.c Overview - </partintro> - - <chapter id="modes_of_use"> - <title>Modes of Use</title> - <sect1> - <title>Manual switching and manual power control</title> -!Pdrivers/gpu/vga/vga_switcheroo.c Manual switching and manual power control - </sect1> - <sect1> - <title>Driver power control</title> -!Pdrivers/gpu/vga/vga_switcheroo.c Driver power control - </sect1> - </chapter> - - <chapter id="api"> - <title>API</title> - <sect1> - <title>Public functions</title> -!Edrivers/gpu/vga/vga_switcheroo.c - </sect1> - <sect1> - <title>Public structures</title> -!Finclude/linux/vga_switcheroo.h vga_switcheroo_handler -!Finclude/linux/vga_switcheroo.h vga_switcheroo_client_ops - </sect1> - <sect1> - <title>Public constants</title> -!Finclude/linux/vga_switcheroo.h vga_switcheroo_handler_flags_t -!Finclude/linux/vga_switcheroo.h vga_switcheroo_client_id -!Finclude/linux/vga_switcheroo.h vga_switcheroo_state - </sect1> - <sect1> - <title>Private structures</title> -!Fdrivers/gpu/vga/vga_switcheroo.c vgasr_priv -!Fdrivers/gpu/vga/vga_switcheroo.c vga_switcheroo_client - </sect1> - </chapter> - - <chapter id="handlers"> - <title>Handlers</title> - <sect1> - <title>apple-gmux Handler</title> -!Pdrivers/platform/x86/apple-gmux.c Overview -!Pdrivers/platform/x86/apple-gmux.c Interrupt - <sect2> - <title>Graphics mux</title> -!Pdrivers/platform/x86/apple-gmux.c Graphics mux - </sect2> - <sect2> - <title>Power control</title> -!Pdrivers/platform/x86/apple-gmux.c Power control - </sect2> - <sect2> - <title>Backlight control</title> -!Pdrivers/platform/x86/apple-gmux.c Backlight control - </sect2> - <sect2> - <title>Public functions</title> -!Iinclude/linux/apple-gmux.h - </sect2> - </sect1> - </chapter> - -!Cdrivers/gpu/vga/vga_switcheroo.c -!Cinclude/linux/vga_switcheroo.h -!Cdrivers/platform/x86/apple-gmux.c -</part> - -</book> diff --git a/Documentation/Makefile.sphinx b/Documentation/Makefile.sphinx new file mode 100644 index 000000000000..addf32309bc3 --- /dev/null +++ b/Documentation/Makefile.sphinx @@ -0,0 +1,63 @@ +# -*- makefile -*- +# Makefile for Sphinx documentation +# + +# You can set these variables from the command line. +SPHINXBUILD = sphinx-build +SPHINXOPTS = +PAPER = +BUILDDIR = $(obj)/output + +# User-friendly check for sphinx-build +HAVE_SPHINX := $(shell if which $(SPHINXBUILD) >/dev/null 2>&1; then echo 1; else echo 0; fi) + +ifeq ($(HAVE_SPHINX),0) + +.DEFAULT: + $(warning The '$(SPHINXBUILD)' command was not found. Make sure you have Sphinx installed and in PATH, or set the SPHINXBUILD make variable to point to the full path of the '$(SPHINXBUILD)' executable.) + @echo " SKIP Sphinx $@ target." + +else # HAVE_SPHINX + +# User-friendly check for rst2pdf +HAVE_RST2PDF := $(shell if python -c "import rst2pdf" >/dev/null 2>&1; then echo 1; else echo 0; fi) + +# Internal variables. +PAPEROPT_a4 = -D latex_paper_size=a4 +PAPEROPT_letter = -D latex_paper_size=letter +KERNELDOC = $(srctree)/scripts/kernel-doc +KERNELDOC_CONF = -D kerneldoc_srctree=$(srctree) -D kerneldoc_bin=$(KERNELDOC) +ALLSPHINXOPTS = -D version=$(KERNELVERSION) -D release=$(KERNELRELEASE) -d $(BUILDDIR)/.doctrees $(KERNELDOC_CONF) $(PAPEROPT_$(PAPER)) -c $(srctree)/$(src) $(SPHINXOPTS) $(srctree)/$(src) +# the i18n builder cannot share the environment and doctrees with the others +I18NSPHINXOPTS = $(PAPEROPT_$(PAPER)) $(SPHINXOPTS) . + +quiet_cmd_sphinx = SPHINX $@ + cmd_sphinx = $(SPHINXBUILD) -b $2 $(ALLSPHINXOPTS) $(BUILDDIR)/$2 + +htmldocs: + $(call cmd,sphinx,html) + +pdfdocs: +ifeq ($(HAVE_RST2PDF),0) + $(warning The Python 'rst2pdf' module was not found. Make sure you have the module installed to produce PDF output.) + @echo " SKIP Sphinx $@ target." +else # HAVE_RST2PDF + $(call cmd,sphinx,pdf) +endif # HAVE_RST2PDF + +epubdocs: + $(call cmd,sphinx,epub) + +xmldocs: + $(call cmd,sphinx,xml) + +# no-ops for the Sphinx toolchain +sgmldocs: +psdocs: +mandocs: +installmandocs: + +cleandocs: + $(Q)rm -rf $(BUILDDIR) + +endif # HAVE_SPHINX diff --git a/Documentation/conf.py b/Documentation/conf.py new file mode 100644 index 000000000000..6cc41a0555a3 --- /dev/null +++ b/Documentation/conf.py @@ -0,0 +1,414 @@ +# -*- coding: utf-8 -*- +# +# The Linux Kernel documentation build configuration file, created by +# sphinx-quickstart on Fri Feb 12 13:51:46 2016. +# +# This file is execfile()d with the current directory set to its +# containing dir. +# +# Note that not all possible configuration values are present in this +# autogenerated file. +# +# All configuration values have a default; values that are commented out +# serve to show the default. + +import sys +import os + +# If extensions (or modules to document with autodoc) are in another directory, +# add these directories to sys.path here. If the directory is relative to the +# documentation root, use os.path.abspath to make it absolute, like shown here. +sys.path.insert(0, os.path.abspath('sphinx')) + +# -- General configuration ------------------------------------------------ + +# If your documentation needs a minimal Sphinx version, state it here. +#needs_sphinx = '1.0' + +# Add any Sphinx extension module names here, as strings. They can be +# extensions coming with Sphinx (named 'sphinx.ext.*') or your custom +# ones. +extensions = ['kernel-doc'] + +# Gracefully handle missing rst2pdf. +try: + import rst2pdf + extensions += ['rst2pdf.pdfbuilder'] +except ImportError: + pass + +# Add any paths that contain templates here, relative to this directory. +templates_path = ['_templates'] + +# The suffix(es) of source filenames. +# You can specify multiple suffix as a list of string: +# source_suffix = ['.rst', '.md'] +source_suffix = '.rst' + +# The encoding of source files. +#source_encoding = 'utf-8-sig' + +# The master toctree document. +master_doc = 'index' + +# General information about the project. +project = 'The Linux Kernel' +copyright = '2016, The kernel development community' +author = 'The kernel development community' + +# The version info for the project you're documenting, acts as replacement for +# |version| and |release|, also used in various other places throughout the +# built documents. +# +# In a normal build, version and release are are set to KERNELVERSION and +# KERNELRELEASE, respectively, from the Makefile via Sphinx command line +# arguments. +# +# The following code tries to extract the information by reading the Makefile, +# when Sphinx is run directly (e.g. by Read the Docs). +try: + makefile_version = None + makefile_patchlevel = None + for line in open('../Makefile'): + key, val = [x.strip() for x in line.split('=', 2)] + if key == 'VERSION': + makefile_version = val + elif key == 'PATCHLEVEL': + makefile_patchlevel = val + if makefile_version and makefile_patchlevel: + break +except: + pass +finally: + if makefile_version and makefile_patchlevel: + version = release = makefile_version + '.' + makefile_patchlevel + else: + sys.stderr.write('Warning: Could not extract kernel version\n') + version = release = "unknown version" + +# The language for content autogenerated by Sphinx. Refer to documentation +# for a list of supported languages. +# +# This is also used if you do content translation via gettext catalogs. +# Usually you set "language" from the command line for these cases. +language = None + +# There are two options for replacing |today|: either, you set today to some +# non-false value, then it is used: +#today = '' +# Else, today_fmt is used as the format for a strftime call. +#today_fmt = '%B %d, %Y' + +# List of patterns, relative to source directory, that match files and +# directories to ignore when looking for source files. +exclude_patterns = ['output'] + +# The reST default role (used for this markup: `text`) to use for all +# documents. +#default_role = None + +# If true, '()' will be appended to :func: etc. cross-reference text. +#add_function_parentheses = True + +# If true, the current module name will be prepended to all description +# unit titles (such as .. function::). +#add_module_names = True + +# If true, sectionauthor and moduleauthor directives will be shown in the +# output. They are ignored by default. +#show_authors = False + +# The name of the Pygments (syntax highlighting) style to use. +pygments_style = 'sphinx' + +# A list of ignored prefixes for module index sorting. +#modindex_common_prefix = [] + +# If true, keep warnings as "system message" paragraphs in the built documents. +#keep_warnings = False + +# If true, `todo` and `todoList` produce output, else they produce nothing. +todo_include_todos = False + +primary_domain = 'C' +highlight_language = 'C' + +# -- Options for HTML output ---------------------------------------------- + +# The theme to use for HTML and HTML Help pages. See the documentation for +# a list of builtin themes. + +# The Read the Docs theme is available from +# - https://github.com/snide/sphinx_rtd_theme +# - https://pypi.python.org/pypi/sphinx_rtd_theme +# - python-sphinx-rtd-theme package (on Debian) +try: + import sphinx_rtd_theme + html_theme = 'sphinx_rtd_theme' + html_theme_path = [sphinx_rtd_theme.get_html_theme_path()] +except ImportError: + sys.stderr.write('Warning: The Sphinx \'sphinx_rtd_theme\' HTML theme was not found. Make sure you have the theme installed to produce pretty HTML output. Falling back to the default theme.\n') + +# Theme options are theme-specific and customize the look and feel of a theme +# further. For a list of options available for each theme, see the +# documentation. +#html_theme_options = {} + +# Add any paths that contain custom themes here, relative to this directory. +#html_theme_path = [] + +# The name for this set of Sphinx documents. If None, it defaults to +# "<project> v<release> documentation". +#html_title = None + +# A shorter title for the navigation bar. Default is the same as html_title. +#html_short_title = None + +# The name of an image file (relative to this directory) to place at the top +# of the sidebar. +#html_logo = None + +# The name of an image file (within the static path) to use as favicon of the +# docs. This file should be a Windows icon file (.ico) being 16x16 or 32x32 +# pixels large. +#html_favicon = None + +# Add any paths that contain custom static files (such as style sheets) here, +# relative to this directory. They are copied after the builtin static files, +# so a file named "default.css" will overwrite the builtin "default.css". +#html_static_path = ['_static'] + +# Add any extra paths that contain custom files (such as robots.txt or +# .htaccess) here, relative to this directory. These files are copied +# directly to the root of the documentation. +#html_extra_path = [] + +# If not '', a 'Last updated on:' timestamp is inserted at every page bottom, +# using the given strftime format. +#html_last_updated_fmt = '%b %d, %Y' + +# If true, SmartyPants will be used to convert quotes and dashes to +# typographically correct entities. +#html_use_smartypants = True + +# Custom sidebar templates, maps document names to template names. +#html_sidebars = {} + +# Additional templates that should be rendered to pages, maps page names to +# template names. +#html_additional_pages = {} + +# If false, no module index is generated. +#html_domain_indices = True + +# If false, no index is generated. +#html_use_index = True + +# If true, the index is split into individual pages for each letter. +#html_split_index = False + +# If true, links to the reST sources are added to the pages. +#html_show_sourcelink = True + +# If true, "Created using Sphinx" is shown in the HTML footer. Default is True. +#html_show_sphinx = True + +# If true, "(C) Copyright ..." is shown in the HTML footer. Default is True. +#html_show_copyright = True + +# If true, an OpenSearch description file will be output, and all pages will +# contain a <link> tag referring to it. The value of this option must be the +# base URL from which the finished HTML is served. +#html_use_opensearch = '' + +# This is the file name suffix for HTML files (e.g. ".xhtml"). +#html_file_suffix = None + +# Language to be used for generating the HTML full-text search index. +# Sphinx supports the following languages: +# 'da', 'de', 'en', 'es', 'fi', 'fr', 'h', 'it', 'ja' +# 'nl', 'no', 'pt', 'ro', 'r', 'sv', 'tr' +#html_search_language = 'en' + +# A dictionary with options for the search language support, empty by default. +# Now only 'ja' uses this config value +#html_search_options = {'type': 'default'} + +# The name of a javascript file (relative to the configuration directory) that +# implements a search results scorer. If empty, the default will be used. +#html_search_scorer = 'scorer.js' + +# Output file base name for HTML help builder. +htmlhelp_basename = 'TheLinuxKerneldoc' + +# -- Options for LaTeX output --------------------------------------------- + +latex_elements = { +# The paper size ('letterpaper' or 'a4paper'). +#'papersize': 'letterpaper', + +# The font size ('10pt', '11pt' or '12pt'). +#'pointsize': '10pt', + +# Additional stuff for the LaTeX preamble. +#'preamble': '', + +# Latex figure (float) alignment +#'figure_align': 'htbp', +} + +# Grouping the document tree into LaTeX files. List of tuples +# (source start file, target name, title, +# author, documentclass [howto, manual, or own class]). +latex_documents = [ + (master_doc, 'TheLinuxKernel.tex', 'The Linux Kernel Documentation', + 'The kernel development community', 'manual'), +] + +# The name of an image file (relative to this directory) to place at the top of +# the title page. +#latex_logo = None + +# For "manual" documents, if this is true, then toplevel headings are parts, +# not chapters. +#latex_use_parts = False + +# If true, show page references after internal links. +#latex_show_pagerefs = False + +# If true, show URL addresses after external links. +#latex_show_urls = False + +# Documents to append as an appendix to all manuals. +#latex_appendices = [] + +# If false, no module index is generated. +#latex_domain_indices = True + + +# -- Options for manual page output --------------------------------------- + +# One entry per manual page. List of tuples +# (source start file, name, description, authors, manual section). +man_pages = [ + (master_doc, 'thelinuxkernel', 'The Linux Kernel Documentation', + [author], 1) +] + +# If true, show URL addresses after external links. +#man_show_urls = False + + +# -- Options for Texinfo output ------------------------------------------- + +# Grouping the document tree into Texinfo files. List of tuples +# (source start file, target name, title, author, +# dir menu entry, description, category) +texinfo_documents = [ + (master_doc, 'TheLinuxKernel', 'The Linux Kernel Documentation', + author, 'TheLinuxKernel', 'One line description of project.', + 'Miscellaneous'), +] + +# Documents to append as an appendix to all manuals. +#texinfo_appendices = [] + +# If false, no module index is generated. +#texinfo_domain_indices = True + +# How to display URL addresses: 'footnote', 'no', or 'inline'. +#texinfo_show_urls = 'footnote' + +# If true, do not generate a @detailmenu in the "Top" node's menu. +#texinfo_no_detailmenu = False + + +# -- Options for Epub output ---------------------------------------------- + +# Bibliographic Dublin Core info. +epub_title = project +epub_author = author +epub_publisher = author +epub_copyright = copyright + +# The basename for the epub file. It defaults to the project name. +#epub_basename = project + +# The HTML theme for the epub output. Since the default themes are not +# optimized for small screen space, using the same theme for HTML and epub +# output is usually not wise. This defaults to 'epub', a theme designed to save +# visual space. +#epub_theme = 'epub' + +# The language of the text. It defaults to the language option +# or 'en' if the language is not set. +#epub_language = '' + +# The scheme of the identifier. Typical schemes are ISBN or URL. +#epub_scheme = '' + +# The unique identifier of the text. This can be a ISBN number +# or the project homepage. +#epub_identifier = '' + +# A unique identification for the text. +#epub_uid = '' + +# A tuple containing the cover image and cover page html template filenames. +#epub_cover = () + +# A sequence of (type, uri, title) tuples for the guide element of content.opf. +#epub_guide = () + +# HTML files that should be inserted before the pages created by sphinx. +# The format is a list of tuples containing the path and title. +#epub_pre_files = [] + +# HTML files that should be inserted after the pages created by sphinx. +# The format is a list of tuples containing the path and title. +#epub_post_files = [] + +# A list of files that should not be packed into the epub file. +epub_exclude_files = ['search.html'] + +# The depth of the table of contents in toc.ncx. +#epub_tocdepth = 3 + +# Allow duplicate toc entries. +#epub_tocdup = True + +# Choose between 'default' and 'includehidden'. +#epub_tocscope = 'default' + +# Fix unsupported image types using the Pillow. +#epub_fix_images = False + +# Scale large images. +#epub_max_image_width = 0 + +# How to display URL addresses: 'footnote', 'no', or 'inline'. +#epub_show_urls = 'inline' + +# If false, no index is generated. +#epub_use_index = True + +#======= +# rst2pdf +# +# Grouping the document tree into PDF files. List of tuples +# (source start file, target name, title, author, options). +# +# See the Sphinx chapter of http://ralsina.me/static/manual.pdf +# +# FIXME: Do not add the index file here; the result will be too big. Adding +# multiple PDF files here actually tries to get the cross-referencing right +# *between* PDF files. +pdf_documents = [ + ('index', u'Kernel', u'Kernel', u'J. Random Bozo'), +] + +# kernel-doc extension configuration for running Sphinx directly (e.g. by Read +# the Docs). In a normal build, these are supplied from the Makefile via command +# line arguments. +kerneldoc_bin = '../scripts/kernel-doc' +kerneldoc_srctree = '..' diff --git a/Documentation/devicetree/bindings/display/arm,malidp.txt b/Documentation/devicetree/bindings/display/arm,malidp.txt new file mode 100644 index 000000000000..2f7870983ef1 --- /dev/null +++ b/Documentation/devicetree/bindings/display/arm,malidp.txt @@ -0,0 +1,65 @@ +ARM Mali-DP + +The following bindings apply to a family of Display Processors sold as +licensable IP by ARM Ltd. The bindings describe the Mali DP500, DP550 and +DP650 processors that offer multiple composition layers, support for +rotation and scaling output. + +Required properties: + - compatible: should be one of + "arm,mali-dp500" + "arm,mali-dp550" + "arm,mali-dp650" + depending on the particular implementation present in the hardware + - reg: Physical base address and size of the block of registers used by + the processor. + - interrupts: Interrupt list, as defined in ../interrupt-controller/interrupts.txt, + interrupt client nodes. + - interrupt-names: name of the engine inside the processor that will + use the corresponding interrupt. Should be one of "DE" or "SE". + - clocks: A list of phandle + clock-specifier pairs, one for each entry + in 'clock-names' + - clock-names: A list of clock names. It should contain: + - "pclk": for the APB interface clock + - "aclk": for the AXI interface clock + - "mclk": for the main processor clock + - "pxlclk": for the pixel clock feeding the output PLL of the processor. + - arm,malidp-output-port-lines: Array of u8 values describing the number + of output lines per channel (R, G and B). + +Required sub-nodes: + - port: The Mali DP connection to an encoder input port. The connection + is modelled using the OF graph bindings specified in + Documentation/devicetree/bindings/graph.txt + +Optional properties: + - memory-region: phandle to a node describing memory (see + Documentation/devicetree/bindings/reserved-memory/reserved-memory.txt) + to be used for the framebuffer; if not present, the framebuffer may + be located anywhere in memory. + + +Example: + +/ { + ... + + dp0: malidp@6f200000 { + compatible = "arm,mali-dp650"; + reg = <0 0x6f200000 0 0x20000>; + memory-region = <&display_reserved>; + interrupts = <0 168 IRQ_TYPE_LEVEL_HIGH>, + <0 168 IRQ_TYPE_LEVEL_HIGH>; + interrupt-names = "DE", "SE"; + clocks = <&oscclk2>, <&fpgaosc0>, <&fpgaosc1>, <&fpgaosc1>; + clock-names = "pxlclk", "mclk", "aclk", "pclk"; + arm,malidp-output-port-lines = /bits/ 8 <8 8 8>; + port { + dp0_output: endpoint { + remote-endpoint = <&tda998x_2_input>; + }; + }; + }; + + ... +}; diff --git a/Documentation/devicetree/bindings/display/bridge/sii902x.txt b/Documentation/devicetree/bindings/display/bridge/sii902x.txt new file mode 100644 index 000000000000..56a3e68ccb80 --- /dev/null +++ b/Documentation/devicetree/bindings/display/bridge/sii902x.txt @@ -0,0 +1,35 @@ +sii902x HDMI bridge bindings + +Required properties: + - compatible: "sil,sii9022" + - reg: i2c address of the bridge + +Optional properties: + - interrupts-extended or interrupt-parent + interrupts: describe + the interrupt line used to inform the host about hotplug events. + - reset-gpios: OF device-tree gpio specification for RST_N pin. + +Optional subnodes: + - video input: this subnode can contain a video input port node + to connect the bridge to a display controller output (See this + documentation [1]). + +[1]: Documentation/devicetree/bindings/media/video-interfaces.txt + +Example: + hdmi-bridge@39 { + compatible = "sil,sii9022"; + reg = <0x39>; + reset-gpios = <&pioA 1 0>; + ports { + #address-cells = <1>; + #size-cells = <0>; + + port@0 { + reg = <0>; + bridge_in: endpoint { + remote-endpoint = <&dc_out>; + }; + }; + }; + }; diff --git a/Documentation/devicetree/bindings/display/panel/panel-dpi.txt b/Documentation/devicetree/bindings/display/panel/panel-dpi.txt index 216c894d4f99..b52ac52757df 100644 --- a/Documentation/devicetree/bindings/display/panel/panel-dpi.txt +++ b/Documentation/devicetree/bindings/display/panel/panel-dpi.txt @@ -7,6 +7,8 @@ Required properties: Optional properties: - label: a symbolic name for the panel - enable-gpios: panel enable gpio +- reset-gpios: GPIO to control the RESET pin +- vcc-supply: phandle of regulator that will be used to enable power to the display Required nodes: - "panel-timing" containing video timings diff --git a/Documentation/dmaengine/provider.txt b/Documentation/dmaengine/provider.txt index 122b7f4876bb..91ce82d5f0c4 100644 --- a/Documentation/dmaengine/provider.txt +++ b/Documentation/dmaengine/provider.txt @@ -323,7 +323,7 @@ supported. * device_resume - Resumes a transfer on the channel - This command should operate synchronously on the channel, - pausing right away the work of the given channel + resuming right away the work of the given channel * device_terminate_all - Aborts all the pending and ongoing transfers on the channel diff --git a/Documentation/gpu/drm-internals.rst b/Documentation/gpu/drm-internals.rst new file mode 100644 index 000000000000..4f7176576feb --- /dev/null +++ b/Documentation/gpu/drm-internals.rst @@ -0,0 +1,378 @@ +============= +DRM Internals +============= + +This chapter documents DRM internals relevant to driver authors and +developers working to add support for the latest features to existing +drivers. + +First, we go over some typical driver initialization requirements, like +setting up command buffers, creating an initial output configuration, +and initializing core services. Subsequent sections cover core internals +in more detail, providing implementation notes and examples. + +The DRM layer provides several services to graphics drivers, many of +them driven by the application interfaces it provides through libdrm, +the library that wraps most of the DRM ioctls. These include vblank +event handling, memory management, output management, framebuffer +management, command submission & fencing, suspend/resume support, and +DMA services. + +Driver Initialization +===================== + +At the core of every DRM driver is a :c:type:`struct drm_driver +<drm_driver>` structure. Drivers typically statically initialize +a drm_driver structure, and then pass it to +:c:func:`drm_dev_alloc()` to allocate a device instance. After the +device instance is fully initialized it can be registered (which makes +it accessible from userspace) using :c:func:`drm_dev_register()`. + +The :c:type:`struct drm_driver <drm_driver>` structure +contains static information that describes the driver and features it +supports, and pointers to methods that the DRM core will call to +implement the DRM API. We will first go through the :c:type:`struct +drm_driver <drm_driver>` static information fields, and will +then describe individual operations in details as they get used in later +sections. + +Driver Information +------------------ + +Driver Features +~~~~~~~~~~~~~~~ + +Drivers inform the DRM core about their requirements and supported +features by setting appropriate flags in the driver_features field. +Since those flags influence the DRM core behaviour since registration +time, most of them must be set to registering the :c:type:`struct +drm_driver <drm_driver>` instance. + +u32 driver_features; + +DRIVER_USE_AGP + Driver uses AGP interface, the DRM core will manage AGP resources. + +DRIVER_REQUIRE_AGP + Driver needs AGP interface to function. AGP initialization failure + will become a fatal error. + +DRIVER_PCI_DMA + Driver is capable of PCI DMA, mapping of PCI DMA buffers to + userspace will be enabled. Deprecated. + +DRIVER_SG + Driver can perform scatter/gather DMA, allocation and mapping of + scatter/gather buffers will be enabled. Deprecated. + +DRIVER_HAVE_DMA + Driver supports DMA, the userspace DMA API will be supported. + Deprecated. + +DRIVER_HAVE_IRQ; DRIVER_IRQ_SHARED + DRIVER_HAVE_IRQ indicates whether the driver has an IRQ handler + managed by the DRM Core. The core will support simple IRQ handler + installation when the flag is set. The installation process is + described in ?. + + DRIVER_IRQ_SHARED indicates whether the device & handler support + shared IRQs (note that this is required of PCI drivers). + +DRIVER_GEM + Driver use the GEM memory manager. + +DRIVER_MODESET + Driver supports mode setting interfaces (KMS). + +DRIVER_PRIME + Driver implements DRM PRIME buffer sharing. + +DRIVER_RENDER + Driver supports dedicated render nodes. + +DRIVER_ATOMIC + Driver supports atomic properties. In this case the driver must + implement appropriate obj->atomic_get_property() vfuncs for any + modeset objects with driver specific properties. + +Major, Minor and Patchlevel +~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +int major; int minor; int patchlevel; +The DRM core identifies driver versions by a major, minor and patch +level triplet. The information is printed to the kernel log at +initialization time and passed to userspace through the +DRM_IOCTL_VERSION ioctl. + +The major and minor numbers are also used to verify the requested driver +API version passed to DRM_IOCTL_SET_VERSION. When the driver API +changes between minor versions, applications can call +DRM_IOCTL_SET_VERSION to select a specific version of the API. If the +requested major isn't equal to the driver major, or the requested minor +is larger than the driver minor, the DRM_IOCTL_SET_VERSION call will +return an error. Otherwise the driver's set_version() method will be +called with the requested version. + +Name, Description and Date +~~~~~~~~~~~~~~~~~~~~~~~~~~ + +char \*name; char \*desc; char \*date; +The driver name is printed to the kernel log at initialization time, +used for IRQ registration and passed to userspace through +DRM_IOCTL_VERSION. + +The driver description is a purely informative string passed to +userspace through the DRM_IOCTL_VERSION ioctl and otherwise unused by +the kernel. + +The driver date, formatted as YYYYMMDD, is meant to identify the date of +the latest modification to the driver. However, as most drivers fail to +update it, its value is mostly useless. The DRM core prints it to the +kernel log at initialization time and passes it to userspace through the +DRM_IOCTL_VERSION ioctl. + +Device Instance and Driver Handling +----------------------------------- + +.. kernel-doc:: drivers/gpu/drm/drm_drv.c + :doc: driver instance overview + +.. kernel-doc:: drivers/gpu/drm/drm_drv.c + :export: + +Driver Load +----------- + +IRQ Registration +~~~~~~~~~~~~~~~~ + +The DRM core tries to facilitate IRQ handler registration and +unregistration by providing :c:func:`drm_irq_install()` and +:c:func:`drm_irq_uninstall()` functions. Those functions only +support a single interrupt per device, devices that use more than one +IRQs need to be handled manually. + +Managed IRQ Registration +'''''''''''''''''''''''' + +:c:func:`drm_irq_install()` starts by calling the irq_preinstall +driver operation. The operation is optional and must make sure that the +interrupt will not get fired by clearing all pending interrupt flags or +disabling the interrupt. + +The passed-in IRQ will then be requested by a call to +:c:func:`request_irq()`. If the DRIVER_IRQ_SHARED driver feature +flag is set, a shared (IRQF_SHARED) IRQ handler will be requested. + +The IRQ handler function must be provided as the mandatory irq_handler +driver operation. It will get passed directly to +:c:func:`request_irq()` and thus has the same prototype as all IRQ +handlers. It will get called with a pointer to the DRM device as the +second argument. + +Finally the function calls the optional irq_postinstall driver +operation. The operation usually enables interrupts (excluding the +vblank interrupt, which is enabled separately), but drivers may choose +to enable/disable interrupts at a different time. + +:c:func:`drm_irq_uninstall()` is similarly used to uninstall an +IRQ handler. It starts by waking up all processes waiting on a vblank +interrupt to make sure they don't hang, and then calls the optional +irq_uninstall driver operation. The operation must disable all hardware +interrupts. Finally the function frees the IRQ by calling +:c:func:`free_irq()`. + +Manual IRQ Registration +''''''''''''''''''''''' + +Drivers that require multiple interrupt handlers can't use the managed +IRQ registration functions. In that case IRQs must be registered and +unregistered manually (usually with the :c:func:`request_irq()` and +:c:func:`free_irq()` functions, or their devm_\* equivalent). + +When manually registering IRQs, drivers must not set the +DRIVER_HAVE_IRQ driver feature flag, and must not provide the +irq_handler driver operation. They must set the :c:type:`struct +drm_device <drm_device>` irq_enabled field to 1 upon +registration of the IRQs, and clear it to 0 after unregistering the +IRQs. + +Memory Manager Initialization +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +Every DRM driver requires a memory manager which must be initialized at +load time. DRM currently contains two memory managers, the Translation +Table Manager (TTM) and the Graphics Execution Manager (GEM). This +document describes the use of the GEM memory manager only. See ? for +details. + +Miscellaneous Device Configuration +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +Another task that may be necessary for PCI devices during configuration +is mapping the video BIOS. On many devices, the VBIOS describes device +configuration, LCD panel timings (if any), and contains flags indicating +device state. Mapping the BIOS can be done using the pci_map_rom() +call, a convenience function that takes care of mapping the actual ROM, +whether it has been shadowed into memory (typically at address 0xc0000) +or exists on the PCI device in the ROM BAR. Note that after the ROM has +been mapped and any necessary information has been extracted, it should +be unmapped; on many devices, the ROM address decoder is shared with +other BARs, so leaving it mapped could cause undesired behaviour like +hangs or memory corruption. + +Bus-specific Device Registration and PCI Support +------------------------------------------------ + +A number of functions are provided to help with device registration. The +functions deal with PCI and platform devices respectively and are only +provided for historical reasons. These are all deprecated and shouldn't +be used in new drivers. Besides that there's a few helpers for pci +drivers. + +.. kernel-doc:: drivers/gpu/drm/drm_pci.c + :export: + +.. kernel-doc:: drivers/gpu/drm/drm_platform.c + :export: + +Open/Close, File Operations and IOCTLs +====================================== + +Open and Close +-------------- + +int (\*firstopen) (struct drm_device \*); void (\*lastclose) (struct +drm_device \*); int (\*open) (struct drm_device \*, struct drm_file +\*); void (\*preclose) (struct drm_device \*, struct drm_file \*); +void (\*postclose) (struct drm_device \*, struct drm_file \*); + Open and close handlers. None of those methods are mandatory. + +The firstopen method is called by the DRM core for legacy UMS (User Mode +Setting) drivers only when an application opens a device that has no +other opened file handle. UMS drivers can implement it to acquire device +resources. KMS drivers can't use the method and must acquire resources +in the load method instead. + +Similarly the lastclose method is called when the last application +holding a file handle opened on the device closes it, for both UMS and +KMS drivers. Additionally, the method is also called at module unload +time or, for hot-pluggable devices, when the device is unplugged. The +firstopen and lastclose calls can thus be unbalanced. + +The open method is called every time the device is opened by an +application. Drivers can allocate per-file private data in this method +and store them in the struct :c:type:`struct drm_file +<drm_file>` driver_priv field. Note that the open method is +called before firstopen. + +The close operation is split into preclose and postclose methods. +Drivers must stop and cleanup all per-file operations in the preclose +method. For instance pending vertical blanking and page flip events must +be cancelled. No per-file operation is allowed on the file handle after +returning from the preclose method. + +Finally the postclose method is called as the last step of the close +operation, right before calling the lastclose method if no other open +file handle exists for the device. Drivers that have allocated per-file +private data in the open method should free it here. + +The lastclose method should restore CRTC and plane properties to default +value, so that a subsequent open of the device will not inherit state +from the previous user. It can also be used to execute delayed power +switching state changes, e.g. in conjunction with the vga_switcheroo +infrastructure (see ?). Beyond that KMS drivers should not do any +further cleanup. Only legacy UMS drivers might need to clean up device +state so that the vga console or an independent fbdev driver could take +over. + +File Operations +--------------- + +.. kernel-doc:: drivers/gpu/drm/drm_fops.c + :doc: file operations + +.. kernel-doc:: drivers/gpu/drm/drm_fops.c + :export: + +IOCTLs +------ + +struct drm_ioctl_desc \*ioctls; int num_ioctls; + Driver-specific ioctls descriptors table. + +Driver-specific ioctls numbers start at DRM_COMMAND_BASE. The ioctls +descriptors table is indexed by the ioctl number offset from the base +value. Drivers can use the DRM_IOCTL_DEF_DRV() macro to initialize +the table entries. + +:: + + DRM_IOCTL_DEF_DRV(ioctl, func, flags) + +``ioctl`` is the ioctl name. Drivers must define the DRM_##ioctl and +DRM_IOCTL_##ioctl macros to the ioctl number offset from +DRM_COMMAND_BASE and the ioctl number respectively. The first macro is +private to the device while the second must be exposed to userspace in a +public header. + +``func`` is a pointer to the ioctl handler function compatible with the +``drm_ioctl_t`` type. + +:: + + typedef int drm_ioctl_t(struct drm_device *dev, void *data, + struct drm_file *file_priv); + +``flags`` is a bitmask combination of the following values. It restricts +how the ioctl is allowed to be called. + +- DRM_AUTH - Only authenticated callers allowed + +- DRM_MASTER - The ioctl can only be called on the master file handle + +- DRM_ROOT_ONLY - Only callers with the SYSADMIN capability allowed + +- DRM_CONTROL_ALLOW - The ioctl can only be called on a control + device + +- DRM_UNLOCKED - The ioctl handler will be called without locking the + DRM global mutex. This is the enforced default for kms drivers (i.e. + using the DRIVER_MODESET flag) and hence shouldn't be used any more + for new drivers. + +.. kernel-doc:: drivers/gpu/drm/drm_ioctl.c + :export: + +Legacy Support Code +=================== + +The section very briefly covers some of the old legacy support code +which is only used by old DRM drivers which have done a so-called +shadow-attach to the underlying device instead of registering as a real +driver. This also includes some of the old generic buffer management and +command submission code. Do not use any of this in new and modern +drivers. + +Legacy Suspend/Resume +--------------------- + +The DRM core provides some suspend/resume code, but drivers wanting full +suspend/resume support should provide save() and restore() functions. +These are called at suspend, hibernate, or resume time, and should +perform any state save or restore required by your device across suspend +or hibernate states. + +int (\*suspend) (struct drm_device \*, pm_message_t state); int +(\*resume) (struct drm_device \*); +Those are legacy suspend and resume methods which *only* work with the +legacy shadow-attach driver registration functions. New driver should +use the power management interface provided by their bus type (usually +through the :c:type:`struct device_driver <device_driver>` +dev_pm_ops) and set these methods to NULL. + +Legacy DMA Services +------------------- + +This should cover how DMA mapping etc. is supported by the core. These +functions are deprecated and should not be used. diff --git a/Documentation/gpu/drm-kms-helpers.rst b/Documentation/gpu/drm-kms-helpers.rst new file mode 100644 index 000000000000..0b302fedf1af --- /dev/null +++ b/Documentation/gpu/drm-kms-helpers.rst @@ -0,0 +1,260 @@ +============================= +Mode Setting Helper Functions +============================= + +The plane, CRTC, encoder and connector functions provided by the drivers +implement the DRM API. They're called by the DRM core and ioctl handlers +to handle device state changes and configuration request. As +implementing those functions often requires logic not specific to +drivers, mid-layer helper functions are available to avoid duplicating +boilerplate code. + +The DRM core contains one mid-layer implementation. The mid-layer +provides implementations of several plane, CRTC, encoder and connector +functions (called from the top of the mid-layer) that pre-process +requests and call lower-level functions provided by the driver (at the +bottom of the mid-layer). For instance, the +:c:func:`drm_crtc_helper_set_config()` function can be used to +fill the :c:type:`struct drm_crtc_funcs <drm_crtc_funcs>` +set_config field. When called, it will split the set_config operation +in smaller, simpler operations and call the driver to handle them. + +To use the mid-layer, drivers call +:c:func:`drm_crtc_helper_add()`, +:c:func:`drm_encoder_helper_add()` and +:c:func:`drm_connector_helper_add()` functions to install their +mid-layer bottom operations handlers, and fill the :c:type:`struct +drm_crtc_funcs <drm_crtc_funcs>`, :c:type:`struct +drm_encoder_funcs <drm_encoder_funcs>` and :c:type:`struct +drm_connector_funcs <drm_connector_funcs>` structures with +pointers to the mid-layer top API functions. Installing the mid-layer +bottom operation handlers is best done right after registering the +corresponding KMS object. + +The mid-layer is not split between CRTC, encoder and connector +operations. To use it, a driver must provide bottom functions for all of +the three KMS entities. + +Atomic Modeset Helper Functions Reference +========================================= + +Overview +-------- + +.. kernel-doc:: drivers/gpu/drm/drm_atomic_helper.c + :doc: overview + +Implementing Asynchronous Atomic Commit +--------------------------------------- + +.. kernel-doc:: drivers/gpu/drm/drm_atomic_helper.c + :doc: implementing nonblocking commit + +Atomic State Reset and Initialization +------------------------------------- + +.. kernel-doc:: drivers/gpu/drm/drm_atomic_helper.c + :doc: atomic state reset and initialization + +.. kernel-doc:: include/drm/drm_atomic_helper.h + :internal: + +.. kernel-doc:: drivers/gpu/drm/drm_atomic_helper.c + :export: + +Modeset Helper Reference for Common Vtables +=========================================== + +.. kernel-doc:: include/drm/drm_modeset_helper_vtables.h + :internal: + +.. kernel-doc:: include/drm/drm_modeset_helper_vtables.h + :doc: overview + +Legacy CRTC/Modeset Helper Functions Reference +============================================== + +.. kernel-doc:: drivers/gpu/drm/drm_crtc_helper.c + :export: + +.. kernel-doc:: drivers/gpu/drm/drm_crtc_helper.c + :doc: overview + +Output Probing Helper Functions Reference +========================================= + +.. kernel-doc:: drivers/gpu/drm/drm_probe_helper.c + :doc: output probing helper overview + +.. kernel-doc:: drivers/gpu/drm/drm_probe_helper.c + :export: + +fbdev Helper Functions Reference +================================ + +.. kernel-doc:: drivers/gpu/drm/drm_fb_helper.c + :doc: fbdev helpers + +.. kernel-doc:: drivers/gpu/drm/drm_fb_helper.c + :export: + +.. kernel-doc:: include/drm/drm_fb_helper.h + :internal: + +Framebuffer CMA Helper Functions Reference +========================================== + +.. kernel-doc:: drivers/gpu/drm/drm_fb_cma_helper.c + :doc: framebuffer cma helper functions + +.. kernel-doc:: drivers/gpu/drm/drm_fb_cma_helper.c + :export: + +Display Port Helper Functions Reference +======================================= + +.. kernel-doc:: drivers/gpu/drm/drm_dp_helper.c + :doc: dp helpers + +.. kernel-doc:: include/drm/drm_dp_helper.h + :internal: + +.. kernel-doc:: drivers/gpu/drm/drm_dp_helper.c + :export: + +Display Port Dual Mode Adaptor Helper Functions Reference +========================================================= + +.. kernel-doc:: drivers/gpu/drm/drm_dp_dual_mode_helper.c + :doc: dp dual mode helpers + +.. kernel-doc:: include/drm/drm_dp_dual_mode_helper.h + :internal: + +.. kernel-doc:: drivers/gpu/drm/drm_dp_dual_mode_helper.c + :export: + +Display Port MST Helper Functions Reference +=========================================== + +.. kernel-doc:: drivers/gpu/drm/drm_dp_mst_topology.c + :doc: dp mst helper + +.. kernel-doc:: include/drm/drm_dp_mst_helper.h + :internal: + +.. kernel-doc:: drivers/gpu/drm/drm_dp_mst_topology.c + :export: + +MIPI DSI Helper Functions Reference +=================================== + +.. kernel-doc:: drivers/gpu/drm/drm_mipi_dsi.c + :doc: dsi helpers + +.. kernel-doc:: include/drm/drm_mipi_dsi.h + :internal: + +.. kernel-doc:: drivers/gpu/drm/drm_mipi_dsi.c + :export: + +EDID Helper Functions Reference +=============================== + +.. kernel-doc:: drivers/gpu/drm/drm_edid.c + :export: + +Rectangle Utilities Reference +============================= + +.. kernel-doc:: include/drm/drm_rect.h + :doc: rect utils + +.. kernel-doc:: include/drm/drm_rect.h + :internal: + +.. kernel-doc:: drivers/gpu/drm/drm_rect.c + :export: + +Flip-work Helper Reference +========================== + +.. kernel-doc:: include/drm/drm_flip_work.h + :doc: flip utils + +.. kernel-doc:: include/drm/drm_flip_work.h + :internal: + +.. kernel-doc:: drivers/gpu/drm/drm_flip_work.c + :export: + +HDMI Infoframes Helper Reference +================================ + +Strictly speaking this is not a DRM helper library but generally useable +by any driver interfacing with HDMI outputs like v4l or alsa drivers. +But it nicely fits into the overall topic of mode setting helper +libraries and hence is also included here. + +.. kernel-doc:: include/linux/hdmi.h + :internal: + +.. kernel-doc:: drivers/video/hdmi.c + :export: + +Plane Helper Reference +====================== + +.. kernel-doc:: drivers/gpu/drm/drm_plane_helper.c + :export: + +.. kernel-doc:: drivers/gpu/drm/drm_plane_helper.c + :doc: overview + +Tile group +---------- + +.. kernel-doc:: drivers/gpu/drm/drm_crtc.c + :doc: Tile group + +Bridges +======= + +Overview +-------- + +.. kernel-doc:: drivers/gpu/drm/drm_bridge.c + :doc: overview + +Default bridge callback sequence +-------------------------------- + +.. kernel-doc:: drivers/gpu/drm/drm_bridge.c + :doc: bridge callbacks + +.. kernel-doc:: drivers/gpu/drm/drm_bridge.c + :export: + +Panel Helper Reference +====================== + +.. kernel-doc:: include/drm/drm_panel.h + :internal: + +.. kernel-doc:: drivers/gpu/drm/drm_panel.c + :export: + +.. kernel-doc:: drivers/gpu/drm/drm_panel.c + :doc: drm panel + +Simple KMS Helper Reference +=========================== + +.. kernel-doc:: include/drm/drm_simple_kms_helper.h + :internal: + +.. kernel-doc:: drivers/gpu/drm/drm_simple_kms_helper.c + :export: + +.. kernel-doc:: drivers/gpu/drm/drm_simple_kms_helper.c + :doc: overview diff --git a/Documentation/gpu/drm-kms.rst b/Documentation/gpu/drm-kms.rst new file mode 100644 index 000000000000..0e1c80436c1d --- /dev/null +++ b/Documentation/gpu/drm-kms.rst @@ -0,0 +1,656 @@ +========================= +Kernel Mode Setting (KMS) +========================= + +Mode Setting +============ + +Drivers must initialize the mode setting core by calling +:c:func:`drm_mode_config_init()` on the DRM device. The function +initializes the :c:type:`struct drm_device <drm_device>` +mode_config field and never fails. Once done, mode configuration must +be setup by initializing the following fields. + +- int min_width, min_height; int max_width, max_height; + Minimum and maximum width and height of the frame buffers in pixel + units. + +- struct drm_mode_config_funcs \*funcs; + Mode setting functions. + +Display Modes Function Reference +-------------------------------- + +.. kernel-doc:: include/drm/drm_modes.h + :internal: + +.. kernel-doc:: drivers/gpu/drm/drm_modes.c + :export: + +Atomic Mode Setting Function Reference +-------------------------------------- + +.. kernel-doc:: drivers/gpu/drm/drm_atomic.c + :export: + +.. kernel-doc:: drivers/gpu/drm/drm_atomic.c + :internal: + +Frame Buffer Abstraction +------------------------ + +Frame buffers are abstract memory objects that provide a source of +pixels to scanout to a CRTC. Applications explicitly request the +creation of frame buffers through the DRM_IOCTL_MODE_ADDFB(2) ioctls +and receive an opaque handle that can be passed to the KMS CRTC control, +plane configuration and page flip functions. + +Frame buffers rely on the underneath memory manager for low-level memory +operations. When creating a frame buffer applications pass a memory +handle (or a list of memory handles for multi-planar formats) through +the ``drm_mode_fb_cmd2`` argument. For drivers using GEM as their +userspace buffer management interface this would be a GEM handle. +Drivers are however free to use their own backing storage object +handles, e.g. vmwgfx directly exposes special TTM handles to userspace +and so expects TTM handles in the create ioctl and not GEM handles. + +The lifetime of a drm framebuffer is controlled with a reference count, +drivers can grab additional references with +:c:func:`drm_framebuffer_reference()`and drop them again with +:c:func:`drm_framebuffer_unreference()`. For driver-private +framebuffers for which the last reference is never dropped (e.g. for the +fbdev framebuffer when the struct :c:type:`struct drm_framebuffer +<drm_framebuffer>` is embedded into the fbdev helper struct) +drivers can manually clean up a framebuffer at module unload time with +:c:func:`drm_framebuffer_unregister_private()`. + +DRM Format Handling +------------------- + +.. kernel-doc:: include/drm/drm_fourcc.h + :internal: + +.. kernel-doc:: drivers/gpu/drm/drm_fourcc.c + :export: + +Dumb Buffer Objects +------------------- + +The KMS API doesn't standardize backing storage object creation and +leaves it to driver-specific ioctls. Furthermore actually creating a +buffer object even for GEM-based drivers is done through a +driver-specific ioctl - GEM only has a common userspace interface for +sharing and destroying objects. While not an issue for full-fledged +graphics stacks that include device-specific userspace components (in +libdrm for instance), this limit makes DRM-based early boot graphics +unnecessarily complex. + +Dumb objects partly alleviate the problem by providing a standard API to +create dumb buffers suitable for scanout, which can then be used to +create KMS frame buffers. + +To support dumb objects drivers must implement the dumb_create, +dumb_destroy and dumb_map_offset operations. + +- int (\*dumb_create)(struct drm_file \*file_priv, struct + drm_device \*dev, struct drm_mode_create_dumb \*args); + The dumb_create operation creates a driver object (GEM or TTM + handle) suitable for scanout based on the width, height and depth + from the struct :c:type:`struct drm_mode_create_dumb + <drm_mode_create_dumb>` argument. It fills the argument's + handle, pitch and size fields with a handle for the newly created + object and its line pitch and size in bytes. + +- int (\*dumb_destroy)(struct drm_file \*file_priv, struct + drm_device \*dev, uint32_t handle); + The dumb_destroy operation destroys a dumb object created by + dumb_create. + +- int (\*dumb_map_offset)(struct drm_file \*file_priv, struct + drm_device \*dev, uint32_t handle, uint64_t \*offset); + The dumb_map_offset operation associates an mmap fake offset with + the object given by the handle and returns it. Drivers must use the + :c:func:`drm_gem_create_mmap_offset()` function to associate + the fake offset as described in ?. + +Note that dumb objects may not be used for gpu acceleration, as has been +attempted on some ARM embedded platforms. Such drivers really must have +a hardware-specific ioctl to allocate suitable buffer objects. + +Output Polling +-------------- + +void (\*output_poll_changed)(struct drm_device \*dev); +This operation notifies the driver that the status of one or more +connectors has changed. Drivers that use the fb helper can just call the +:c:func:`drm_fb_helper_hotplug_event()` function to handle this +operation. + +KMS Initialization and Cleanup +============================== + +A KMS device is abstracted and exposed as a set of planes, CRTCs, +encoders and connectors. KMS drivers must thus create and initialize all +those objects at load time after initializing mode setting. + +CRTCs (:c:type:`struct drm_crtc <drm_crtc>`) +-------------------------------------------- + +A CRTC is an abstraction representing a part of the chip that contains a +pointer to a scanout buffer. Therefore, the number of CRTCs available +determines how many independent scanout buffers can be active at any +given time. The CRTC structure contains several fields to support this: +a pointer to some video memory (abstracted as a frame buffer object), a +display mode, and an (x, y) offset into the video memory to support +panning or configurations where one piece of video memory spans multiple +CRTCs. + +CRTC Initialization +~~~~~~~~~~~~~~~~~~~ + +A KMS device must create and register at least one struct +:c:type:`struct drm_crtc <drm_crtc>` instance. The instance is +allocated and zeroed by the driver, possibly as part of a larger +structure, and registered with a call to :c:func:`drm_crtc_init()` +with a pointer to CRTC functions. + +Planes (:c:type:`struct drm_plane <drm_plane>`) +----------------------------------------------- + +A plane represents an image source that can be blended with or overlayed +on top of a CRTC during the scanout process. Planes are associated with +a frame buffer to crop a portion of the image memory (source) and +optionally scale it to a destination size. The result is then blended +with or overlayed on top of a CRTC. + +The DRM core recognizes three types of planes: + +- DRM_PLANE_TYPE_PRIMARY represents a "main" plane for a CRTC. + Primary planes are the planes operated upon by CRTC modesetting and + flipping operations described in the page_flip hook in + :c:type:`struct drm_crtc_funcs <drm_crtc_funcs>`. +- DRM_PLANE_TYPE_CURSOR represents a "cursor" plane for a CRTC. + Cursor planes are the planes operated upon by the + DRM_IOCTL_MODE_CURSOR and DRM_IOCTL_MODE_CURSOR2 ioctls. +- DRM_PLANE_TYPE_OVERLAY represents all non-primary, non-cursor + planes. Some drivers refer to these types of planes as "sprites" + internally. + +For compatibility with legacy userspace, only overlay planes are made +available to userspace by default. Userspace clients may set the +DRM_CLIENT_CAP_UNIVERSAL_PLANES client capability bit to indicate +that they wish to receive a universal plane list containing all plane +types. + +Plane Initialization +~~~~~~~~~~~~~~~~~~~~ + +To create a plane, a KMS drivers allocates and zeroes an instances of +:c:type:`struct drm_plane <drm_plane>` (possibly as part of a +larger structure) and registers it with a call to +:c:func:`drm_universal_plane_init()`. The function takes a +bitmask of the CRTCs that can be associated with the plane, a pointer to +the plane functions, a list of format supported formats, and the type of +plane (primary, cursor, or overlay) being initialized. + +Cursor and overlay planes are optional. All drivers should provide one +primary plane per CRTC (although this requirement may change in the +future); drivers that do not wish to provide special handling for +primary planes may make use of the helper functions described in ? to +create and register a primary plane with standard capabilities. + +Encoders (:c:type:`struct drm_encoder <drm_encoder>`) +----------------------------------------------------- + +An encoder takes pixel data from a CRTC and converts it to a format +suitable for any attached connectors. On some devices, it may be +possible to have a CRTC send data to more than one encoder. In that +case, both encoders would receive data from the same scanout buffer, +resulting in a "cloned" display configuration across the connectors +attached to each encoder. + +Encoder Initialization +~~~~~~~~~~~~~~~~~~~~~~ + +As for CRTCs, a KMS driver must create, initialize and register at least +one :c:type:`struct drm_encoder <drm_encoder>` instance. The +instance is allocated and zeroed by the driver, possibly as part of a +larger structure. + +Drivers must initialize the :c:type:`struct drm_encoder +<drm_encoder>` possible_crtcs and possible_clones fields before +registering the encoder. Both fields are bitmasks of respectively the +CRTCs that the encoder can be connected to, and sibling encoders +candidate for cloning. + +After being initialized, the encoder must be registered with a call to +:c:func:`drm_encoder_init()`. The function takes a pointer to the +encoder functions and an encoder type. Supported types are + +- DRM_MODE_ENCODER_DAC for VGA and analog on DVI-I/DVI-A +- DRM_MODE_ENCODER_TMDS for DVI, HDMI and (embedded) DisplayPort +- DRM_MODE_ENCODER_LVDS for display panels +- DRM_MODE_ENCODER_TVDAC for TV output (Composite, S-Video, + Component, SCART) +- DRM_MODE_ENCODER_VIRTUAL for virtual machine displays + +Encoders must be attached to a CRTC to be used. DRM drivers leave +encoders unattached at initialization time. Applications (or the fbdev +compatibility layer when implemented) are responsible for attaching the +encoders they want to use to a CRTC. + +Connectors (:c:type:`struct drm_connector <drm_connector>`) +----------------------------------------------------------- + +A connector is the final destination for pixel data on a device, and +usually connects directly to an external display device like a monitor +or laptop panel. A connector can only be attached to one encoder at a +time. The connector is also the structure where information about the +attached display is kept, so it contains fields for display data, EDID +data, DPMS & connection status, and information about modes supported on +the attached displays. + +Connector Initialization +~~~~~~~~~~~~~~~~~~~~~~~~ + +Finally a KMS driver must create, initialize, register and attach at +least one :c:type:`struct drm_connector <drm_connector>` +instance. The instance is created as other KMS objects and initialized +by setting the following fields. + +interlace_allowed + Whether the connector can handle interlaced modes. + +doublescan_allowed + Whether the connector can handle doublescan. + +display_info + Display information is filled from EDID information when a display + is detected. For non hot-pluggable displays such as flat panels in + embedded systems, the driver should initialize the + display_info.width_mm and display_info.height_mm fields with the + physical size of the display. + +polled + Connector polling mode, a combination of + + DRM_CONNECTOR_POLL_HPD + The connector generates hotplug events and doesn't need to be + periodically polled. The CONNECT and DISCONNECT flags must not + be set together with the HPD flag. + + DRM_CONNECTOR_POLL_CONNECT + Periodically poll the connector for connection. + + DRM_CONNECTOR_POLL_DISCONNECT + Periodically poll the connector for disconnection. + + Set to 0 for connectors that don't support connection status + discovery. + +The connector is then registered with a call to +:c:func:`drm_connector_init()` with a pointer to the connector +functions and a connector type, and exposed through sysfs with a call to +:c:func:`drm_connector_register()`. + +Supported connector types are + +- DRM_MODE_CONNECTOR_VGA +- DRM_MODE_CONNECTOR_DVII +- DRM_MODE_CONNECTOR_DVID +- DRM_MODE_CONNECTOR_DVIA +- DRM_MODE_CONNECTOR_Composite +- DRM_MODE_CONNECTOR_SVIDEO +- DRM_MODE_CONNECTOR_LVDS +- DRM_MODE_CONNECTOR_Component +- DRM_MODE_CONNECTOR_9PinDIN +- DRM_MODE_CONNECTOR_DisplayPort +- DRM_MODE_CONNECTOR_HDMIA +- DRM_MODE_CONNECTOR_HDMIB +- DRM_MODE_CONNECTOR_TV +- DRM_MODE_CONNECTOR_eDP +- DRM_MODE_CONNECTOR_VIRTUAL + +Connectors must be attached to an encoder to be used. For devices that +map connectors to encoders 1:1, the connector should be attached at +initialization time with a call to +:c:func:`drm_mode_connector_attach_encoder()`. The driver must +also set the :c:type:`struct drm_connector <drm_connector>` +encoder field to point to the attached encoder. + +Finally, drivers must initialize the connectors state change detection +with a call to :c:func:`drm_kms_helper_poll_init()`. If at least +one connector is pollable but can't generate hotplug interrupts +(indicated by the DRM_CONNECTOR_POLL_CONNECT and +DRM_CONNECTOR_POLL_DISCONNECT connector flags), a delayed work will +automatically be queued to periodically poll for changes. Connectors +that can generate hotplug interrupts must be marked with the +DRM_CONNECTOR_POLL_HPD flag instead, and their interrupt handler must +call :c:func:`drm_helper_hpd_irq_event()`. The function will +queue a delayed work to check the state of all connectors, but no +periodic polling will be done. + +Connector Operations +~~~~~~~~~~~~~~~~~~~~ + + **Note** + + Unless otherwise state, all operations are mandatory. + +DPMS +'''' + +void (\*dpms)(struct drm_connector \*connector, int mode); +The DPMS operation sets the power state of a connector. The mode +argument is one of + +- DRM_MODE_DPMS_ON + +- DRM_MODE_DPMS_STANDBY + +- DRM_MODE_DPMS_SUSPEND + +- DRM_MODE_DPMS_OFF + +In all but DPMS_ON mode the encoder to which the connector is attached +should put the display in low-power mode by driving its signals +appropriately. If more than one connector is attached to the encoder +care should be taken not to change the power state of other displays as +a side effect. Low-power mode should be propagated to the encoders and +CRTCs when all related connectors are put in low-power mode. + +Modes +''''' + +int (\*fill_modes)(struct drm_connector \*connector, uint32_t +max_width, uint32_t max_height); +Fill the mode list with all supported modes for the connector. If the +``max_width`` and ``max_height`` arguments are non-zero, the +implementation must ignore all modes wider than ``max_width`` or higher +than ``max_height``. + +The connector must also fill in this operation its display_info +width_mm and height_mm fields with the connected display physical size +in millimeters. The fields should be set to 0 if the value isn't known +or is not applicable (for instance for projector devices). + +Connection Status +''''''''''''''''' + +The connection status is updated through polling or hotplug events when +supported (see ?). The status value is reported to userspace through +ioctls and must not be used inside the driver, as it only gets +initialized by a call to :c:func:`drm_mode_getconnector()` from +userspace. + +enum drm_connector_status (\*detect)(struct drm_connector +\*connector, bool force); +Check to see if anything is attached to the connector. The ``force`` +parameter is set to false whilst polling or to true when checking the +connector due to user request. ``force`` can be used by the driver to +avoid expensive, destructive operations during automated probing. + +Return connector_status_connected if something is connected to the +connector, connector_status_disconnected if nothing is connected and +connector_status_unknown if the connection state isn't known. + +Drivers should only return connector_status_connected if the +connection status has really been probed as connected. Connectors that +can't detect the connection status, or failed connection status probes, +should return connector_status_unknown. + +Cleanup +------- + +The DRM core manages its objects' lifetime. When an object is not needed +anymore the core calls its destroy function, which must clean up and +free every resource allocated for the object. Every +:c:func:`drm_\*_init()` call must be matched with a corresponding +:c:func:`drm_\*_cleanup()` call to cleanup CRTCs +(:c:func:`drm_crtc_cleanup()`), planes +(:c:func:`drm_plane_cleanup()`), encoders +(:c:func:`drm_encoder_cleanup()`) and connectors +(:c:func:`drm_connector_cleanup()`). Furthermore, connectors that +have been added to sysfs must be removed by a call to +:c:func:`drm_connector_unregister()` before calling +:c:func:`drm_connector_cleanup()`. + +Connectors state change detection must be cleanup up with a call to +:c:func:`drm_kms_helper_poll_fini()`. + +Output discovery and initialization example +------------------------------------------- + +:: + + void intel_crt_init(struct drm_device *dev) + { + struct drm_connector *connector; + struct intel_output *intel_output; + + intel_output = kzalloc(sizeof(struct intel_output), GFP_KERNEL); + if (!intel_output) + return; + + connector = &intel_output->base; + drm_connector_init(dev, &intel_output->base, + &intel_crt_connector_funcs, DRM_MODE_CONNECTOR_VGA); + + drm_encoder_init(dev, &intel_output->enc, &intel_crt_enc_funcs, + DRM_MODE_ENCODER_DAC); + + drm_mode_connector_attach_encoder(&intel_output->base, + &intel_output->enc); + + /* Set up the DDC bus. */ + intel_output->ddc_bus = intel_i2c_create(dev, GPIOA, "CRTDDC_A"); + if (!intel_output->ddc_bus) { + dev_printk(KERN_ERR, &dev->pdev->dev, "DDC bus registration " + "failed.\n"); + return; + } + + intel_output->type = INTEL_OUTPUT_ANALOG; + connector->interlace_allowed = 0; + connector->doublescan_allowed = 0; + + drm_encoder_helper_add(&intel_output->enc, &intel_crt_helper_funcs); + drm_connector_helper_add(connector, &intel_crt_connector_helper_funcs); + + drm_connector_register(connector); + } + +In the example above (taken from the i915 driver), a CRTC, connector and +encoder combination is created. A device-specific i2c bus is also +created for fetching EDID data and performing monitor detection. Once +the process is complete, the new connector is registered with sysfs to +make its properties available to applications. + +KMS API Functions +----------------- + +.. kernel-doc:: drivers/gpu/drm/drm_crtc.c + :export: + +KMS Data Structures +------------------- + +.. kernel-doc:: include/drm/drm_crtc.h + :internal: + +KMS Locking +----------- + +.. kernel-doc:: drivers/gpu/drm/drm_modeset_lock.c + :doc: kms locking + +.. kernel-doc:: include/drm/drm_modeset_lock.h + :internal: + +.. kernel-doc:: drivers/gpu/drm/drm_modeset_lock.c + :export: + +KMS Properties +============== + +Drivers may need to expose additional parameters to applications than +those described in the previous sections. KMS supports attaching +properties to CRTCs, connectors and planes and offers a userspace API to +list, get and set the property values. + +Properties are identified by a name that uniquely defines the property +purpose, and store an associated value. For all property types except +blob properties the value is a 64-bit unsigned integer. + +KMS differentiates between properties and property instances. Drivers +first create properties and then create and associate individual +instances of those properties to objects. A property can be instantiated +multiple times and associated with different objects. Values are stored +in property instances, and all other property information are stored in +the property and shared between all instances of the property. + +Every property is created with a type that influences how the KMS core +handles the property. Supported property types are + +DRM_MODE_PROP_RANGE + Range properties report their minimum and maximum admissible values. + The KMS core verifies that values set by application fit in that + range. + +DRM_MODE_PROP_ENUM + Enumerated properties take a numerical value that ranges from 0 to + the number of enumerated values defined by the property minus one, + and associate a free-formed string name to each value. Applications + can retrieve the list of defined value-name pairs and use the + numerical value to get and set property instance values. + +DRM_MODE_PROP_BITMASK + Bitmask properties are enumeration properties that additionally + restrict all enumerated values to the 0..63 range. Bitmask property + instance values combine one or more of the enumerated bits defined + by the property. + +DRM_MODE_PROP_BLOB + Blob properties store a binary blob without any format restriction. + The binary blobs are created as KMS standalone objects, and blob + property instance values store the ID of their associated blob + object. + + Blob properties are only used for the connector EDID property and + cannot be created by drivers. + +To create a property drivers call one of the following functions +depending on the property type. All property creation functions take +property flags and name, as well as type-specific arguments. + +- struct drm_property \*drm_property_create_range(struct + drm_device \*dev, int flags, const char \*name, uint64_t min, + uint64_t max); + Create a range property with the given minimum and maximum values. + +- struct drm_property \*drm_property_create_enum(struct drm_device + \*dev, int flags, const char \*name, const struct + drm_prop_enum_list \*props, int num_values); + Create an enumerated property. The ``props`` argument points to an + array of ``num_values`` value-name pairs. + +- struct drm_property \*drm_property_create_bitmask(struct + drm_device \*dev, int flags, const char \*name, const struct + drm_prop_enum_list \*props, int num_values); + Create a bitmask property. The ``props`` argument points to an array + of ``num_values`` value-name pairs. + +Properties can additionally be created as immutable, in which case they +will be read-only for applications but can be modified by the driver. To +create an immutable property drivers must set the +DRM_MODE_PROP_IMMUTABLE flag at property creation time. + +When no array of value-name pairs is readily available at property +creation time for enumerated or range properties, drivers can create the +property using the :c:func:`drm_property_create()` function and +manually add enumeration value-name pairs by calling the +:c:func:`drm_property_add_enum()` function. Care must be taken to +properly specify the property type through the ``flags`` argument. + +After creating properties drivers can attach property instances to CRTC, +connector and plane objects by calling the +:c:func:`drm_object_attach_property()`. The function takes a +pointer to the target object, a pointer to the previously created +property and an initial instance value. + +Existing KMS Properties +----------------------- + +The following table gives description of drm properties exposed by +various modules/drivers. + +.. csv-table:: + :header-rows: 1 + :file: kms-properties.csv + +Vertical Blanking +================= + +Vertical blanking plays a major role in graphics rendering. To achieve +tear-free display, users must synchronize page flips and/or rendering to +vertical blanking. The DRM API offers ioctls to perform page flips +synchronized to vertical blanking and wait for vertical blanking. + +The DRM core handles most of the vertical blanking management logic, +which involves filtering out spurious interrupts, keeping race-free +blanking counters, coping with counter wrap-around and resets and +keeping use counts. It relies on the driver to generate vertical +blanking interrupts and optionally provide a hardware vertical blanking +counter. Drivers must implement the following operations. + +- int (\*enable_vblank) (struct drm_device \*dev, int crtc); void + (\*disable_vblank) (struct drm_device \*dev, int crtc); + Enable or disable vertical blanking interrupts for the given CRTC. + +- u32 (\*get_vblank_counter) (struct drm_device \*dev, int crtc); + Retrieve the value of the vertical blanking counter for the given + CRTC. If the hardware maintains a vertical blanking counter its value + should be returned. Otherwise drivers can use the + :c:func:`drm_vblank_count()` helper function to handle this + operation. + +Drivers must initialize the vertical blanking handling core with a call +to :c:func:`drm_vblank_init()` in their load operation. + +Vertical blanking interrupts can be enabled by the DRM core or by +drivers themselves (for instance to handle page flipping operations). +The DRM core maintains a vertical blanking use count to ensure that the +interrupts are not disabled while a user still needs them. To increment +the use count, drivers call :c:func:`drm_vblank_get()`. Upon +return vertical blanking interrupts are guaranteed to be enabled. + +To decrement the use count drivers call +:c:func:`drm_vblank_put()`. Only when the use count drops to zero +will the DRM core disable the vertical blanking interrupts after a delay +by scheduling a timer. The delay is accessible through the +vblankoffdelay module parameter or the ``drm_vblank_offdelay`` global +variable and expressed in milliseconds. Its default value is 5000 ms. +Zero means never disable, and a negative value means disable +immediately. Drivers may override the behaviour by setting the +:c:type:`struct drm_device <drm_device>` +vblank_disable_immediate flag, which when set causes vblank interrupts +to be disabled immediately regardless of the drm_vblank_offdelay +value. The flag should only be set if there's a properly working +hardware vblank counter present. + +When a vertical blanking interrupt occurs drivers only need to call the +:c:func:`drm_handle_vblank()` function to account for the +interrupt. + +Resources allocated by :c:func:`drm_vblank_init()` must be freed +with a call to :c:func:`drm_vblank_cleanup()` in the driver unload +operation handler. + +Vertical Blanking and Interrupt Handling Functions Reference +------------------------------------------------------------ + +.. kernel-doc:: drivers/gpu/drm/drm_irq.c + :export: + +.. kernel-doc:: include/drm/drmP.h + :functions: drm_crtc_vblank_waitqueue diff --git a/Documentation/gpu/drm-mm.rst b/Documentation/gpu/drm-mm.rst new file mode 100644 index 000000000000..59f9822fecd0 --- /dev/null +++ b/Documentation/gpu/drm-mm.rst @@ -0,0 +1,454 @@ +===================== +DRM Memory Management +===================== + +Modern Linux systems require large amount of graphics memory to store +frame buffers, textures, vertices and other graphics-related data. Given +the very dynamic nature of many of that data, managing graphics memory +efficiently is thus crucial for the graphics stack and plays a central +role in the DRM infrastructure. + +The DRM core includes two memory managers, namely Translation Table Maps +(TTM) and Graphics Execution Manager (GEM). TTM was the first DRM memory +manager to be developed and tried to be a one-size-fits-them all +solution. It provides a single userspace API to accommodate the need of +all hardware, supporting both Unified Memory Architecture (UMA) devices +and devices with dedicated video RAM (i.e. most discrete video cards). +This resulted in a large, complex piece of code that turned out to be +hard to use for driver development. + +GEM started as an Intel-sponsored project in reaction to TTM's +complexity. Its design philosophy is completely different: instead of +providing a solution to every graphics memory-related problems, GEM +identified common code between drivers and created a support library to +share it. GEM has simpler initialization and execution requirements than +TTM, but has no video RAM management capabilities and is thus limited to +UMA devices. + +The Translation Table Manager (TTM) +----------------------------------- + +TTM design background and information belongs here. + +TTM initialization +~~~~~~~~~~~~~~~~~~ + + **Warning** + + This section is outdated. + +Drivers wishing to support TTM must fill out a drm_bo_driver +structure. The structure contains several fields with function pointers +for initializing the TTM, allocating and freeing memory, waiting for +command completion and fence synchronization, and memory migration. See +the radeon_ttm.c file for an example of usage. + +The ttm_global_reference structure is made up of several fields: + +:: + + struct ttm_global_reference { + enum ttm_global_types global_type; + size_t size; + void *object; + int (*init) (struct ttm_global_reference *); + void (*release) (struct ttm_global_reference *); + }; + + +There should be one global reference structure for your memory manager +as a whole, and there will be others for each object created by the +memory manager at runtime. Your global TTM should have a type of +TTM_GLOBAL_TTM_MEM. The size field for the global object should be +sizeof(struct ttm_mem_global), and the init and release hooks should +point at your driver-specific init and release routines, which probably +eventually call ttm_mem_global_init and ttm_mem_global_release, +respectively. + +Once your global TTM accounting structure is set up and initialized by +calling ttm_global_item_ref() on it, you need to create a buffer +object TTM to provide a pool for buffer object allocation by clients and +the kernel itself. The type of this object should be +TTM_GLOBAL_TTM_BO, and its size should be sizeof(struct +ttm_bo_global). Again, driver-specific init and release functions may +be provided, likely eventually calling ttm_bo_global_init() and +ttm_bo_global_release(), respectively. Also, like the previous +object, ttm_global_item_ref() is used to create an initial reference +count for the TTM, which will call your initialization function. + +The Graphics Execution Manager (GEM) +------------------------------------ + +The GEM design approach has resulted in a memory manager that doesn't +provide full coverage of all (or even all common) use cases in its +userspace or kernel API. GEM exposes a set of standard memory-related +operations to userspace and a set of helper functions to drivers, and +let drivers implement hardware-specific operations with their own +private API. + +The GEM userspace API is described in the `GEM - the Graphics Execution +Manager <http://lwn.net/Articles/283798/>`__ article on LWN. While +slightly outdated, the document provides a good overview of the GEM API +principles. Buffer allocation and read and write operations, described +as part of the common GEM API, are currently implemented using +driver-specific ioctls. + +GEM is data-agnostic. It manages abstract buffer objects without knowing +what individual buffers contain. APIs that require knowledge of buffer +contents or purpose, such as buffer allocation or synchronization +primitives, are thus outside of the scope of GEM and must be implemented +using driver-specific ioctls. + +On a fundamental level, GEM involves several operations: + +- Memory allocation and freeing +- Command execution +- Aperture management at command execution time + +Buffer object allocation is relatively straightforward and largely +provided by Linux's shmem layer, which provides memory to back each +object. + +Device-specific operations, such as command execution, pinning, buffer +read & write, mapping, and domain ownership transfers are left to +driver-specific ioctls. + +GEM Initialization +~~~~~~~~~~~~~~~~~~ + +Drivers that use GEM must set the DRIVER_GEM bit in the struct +:c:type:`struct drm_driver <drm_driver>` driver_features +field. The DRM core will then automatically initialize the GEM core +before calling the load operation. Behind the scene, this will create a +DRM Memory Manager object which provides an address space pool for +object allocation. + +In a KMS configuration, drivers need to allocate and initialize a +command ring buffer following core GEM initialization if required by the +hardware. UMA devices usually have what is called a "stolen" memory +region, which provides space for the initial framebuffer and large, +contiguous memory regions required by the device. This space is +typically not managed by GEM, and must be initialized separately into +its own DRM MM object. + +GEM Objects Creation +~~~~~~~~~~~~~~~~~~~~ + +GEM splits creation of GEM objects and allocation of the memory that +backs them in two distinct operations. + +GEM objects are represented by an instance of struct :c:type:`struct +drm_gem_object <drm_gem_object>`. Drivers usually need to +extend GEM objects with private information and thus create a +driver-specific GEM object structure type that embeds an instance of +struct :c:type:`struct drm_gem_object <drm_gem_object>`. + +To create a GEM object, a driver allocates memory for an instance of its +specific GEM object type and initializes the embedded struct +:c:type:`struct drm_gem_object <drm_gem_object>` with a call +to :c:func:`drm_gem_object_init()`. The function takes a pointer +to the DRM device, a pointer to the GEM object and the buffer object +size in bytes. + +GEM uses shmem to allocate anonymous pageable memory. +:c:func:`drm_gem_object_init()` will create an shmfs file of the +requested size and store it into the struct :c:type:`struct +drm_gem_object <drm_gem_object>` filp field. The memory is +used as either main storage for the object when the graphics hardware +uses system memory directly or as a backing store otherwise. + +Drivers are responsible for the actual physical pages allocation by +calling :c:func:`shmem_read_mapping_page_gfp()` for each page. +Note that they can decide to allocate pages when initializing the GEM +object, or to delay allocation until the memory is needed (for instance +when a page fault occurs as a result of a userspace memory access or +when the driver needs to start a DMA transfer involving the memory). + +Anonymous pageable memory allocation is not always desired, for instance +when the hardware requires physically contiguous system memory as is +often the case in embedded devices. Drivers can create GEM objects with +no shmfs backing (called private GEM objects) by initializing them with +a call to :c:func:`drm_gem_private_object_init()` instead of +:c:func:`drm_gem_object_init()`. Storage for private GEM objects +must be managed by drivers. + +GEM Objects Lifetime +~~~~~~~~~~~~~~~~~~~~ + +All GEM objects are reference-counted by the GEM core. References can be +acquired and release by :c:func:`calling +drm_gem_object_reference()` and +:c:func:`drm_gem_object_unreference()` respectively. The caller +must hold the :c:type:`struct drm_device <drm_device>` +struct_mutex lock when calling +:c:func:`drm_gem_object_reference()`. As a convenience, GEM +provides :c:func:`drm_gem_object_unreference_unlocked()` +functions that can be called without holding the lock. + +When the last reference to a GEM object is released the GEM core calls +the :c:type:`struct drm_driver <drm_driver>` gem_free_object +operation. That operation is mandatory for GEM-enabled drivers and must +free the GEM object and all associated resources. + +void (\*gem_free_object) (struct drm_gem_object \*obj); Drivers are +responsible for freeing all GEM object resources. This includes the +resources created by the GEM core, which need to be released with +:c:func:`drm_gem_object_release()`. + +GEM Objects Naming +~~~~~~~~~~~~~~~~~~ + +Communication between userspace and the kernel refers to GEM objects +using local handles, global names or, more recently, file descriptors. +All of those are 32-bit integer values; the usual Linux kernel limits +apply to the file descriptors. + +GEM handles are local to a DRM file. Applications get a handle to a GEM +object through a driver-specific ioctl, and can use that handle to refer +to the GEM object in other standard or driver-specific ioctls. Closing a +DRM file handle frees all its GEM handles and dereferences the +associated GEM objects. + +To create a handle for a GEM object drivers call +:c:func:`drm_gem_handle_create()`. The function takes a pointer +to the DRM file and the GEM object and returns a locally unique handle. +When the handle is no longer needed drivers delete it with a call to +:c:func:`drm_gem_handle_delete()`. Finally the GEM object +associated with a handle can be retrieved by a call to +:c:func:`drm_gem_object_lookup()`. + +Handles don't take ownership of GEM objects, they only take a reference +to the object that will be dropped when the handle is destroyed. To +avoid leaking GEM objects, drivers must make sure they drop the +reference(s) they own (such as the initial reference taken at object +creation time) as appropriate, without any special consideration for the +handle. For example, in the particular case of combined GEM object and +handle creation in the implementation of the dumb_create operation, +drivers must drop the initial reference to the GEM object before +returning the handle. + +GEM names are similar in purpose to handles but are not local to DRM +files. They can be passed between processes to reference a GEM object +globally. Names can't be used directly to refer to objects in the DRM +API, applications must convert handles to names and names to handles +using the DRM_IOCTL_GEM_FLINK and DRM_IOCTL_GEM_OPEN ioctls +respectively. The conversion is handled by the DRM core without any +driver-specific support. + +GEM also supports buffer sharing with dma-buf file descriptors through +PRIME. GEM-based drivers must use the provided helpers functions to +implement the exporting and importing correctly. See ?. Since sharing +file descriptors is inherently more secure than the easily guessable and +global GEM names it is the preferred buffer sharing mechanism. Sharing +buffers through GEM names is only supported for legacy userspace. +Furthermore PRIME also allows cross-device buffer sharing since it is +based on dma-bufs. + +GEM Objects Mapping +~~~~~~~~~~~~~~~~~~~ + +Because mapping operations are fairly heavyweight GEM favours +read/write-like access to buffers, implemented through driver-specific +ioctls, over mapping buffers to userspace. However, when random access +to the buffer is needed (to perform software rendering for instance), +direct access to the object can be more efficient. + +The mmap system call can't be used directly to map GEM objects, as they +don't have their own file handle. Two alternative methods currently +co-exist to map GEM objects to userspace. The first method uses a +driver-specific ioctl to perform the mapping operation, calling +:c:func:`do_mmap()` under the hood. This is often considered +dubious, seems to be discouraged for new GEM-enabled drivers, and will +thus not be described here. + +The second method uses the mmap system call on the DRM file handle. void +\*mmap(void \*addr, size_t length, int prot, int flags, int fd, off_t +offset); DRM identifies the GEM object to be mapped by a fake offset +passed through the mmap offset argument. Prior to being mapped, a GEM +object must thus be associated with a fake offset. To do so, drivers +must call :c:func:`drm_gem_create_mmap_offset()` on the object. + +Once allocated, the fake offset value must be passed to the application +in a driver-specific way and can then be used as the mmap offset +argument. + +The GEM core provides a helper method :c:func:`drm_gem_mmap()` to +handle object mapping. The method can be set directly as the mmap file +operation handler. It will look up the GEM object based on the offset +value and set the VMA operations to the :c:type:`struct drm_driver +<drm_driver>` gem_vm_ops field. Note that +:c:func:`drm_gem_mmap()` doesn't map memory to userspace, but +relies on the driver-provided fault handler to map pages individually. + +To use :c:func:`drm_gem_mmap()`, drivers must fill the struct +:c:type:`struct drm_driver <drm_driver>` gem_vm_ops field +with a pointer to VM operations. + +struct vm_operations_struct \*gem_vm_ops struct +vm_operations_struct { void (\*open)(struct vm_area_struct \* area); +void (\*close)(struct vm_area_struct \* area); int (\*fault)(struct +vm_area_struct \*vma, struct vm_fault \*vmf); }; + +The open and close operations must update the GEM object reference +count. Drivers can use the :c:func:`drm_gem_vm_open()` and +:c:func:`drm_gem_vm_close()` helper functions directly as open +and close handlers. + +The fault operation handler is responsible for mapping individual pages +to userspace when a page fault occurs. Depending on the memory +allocation scheme, drivers can allocate pages at fault time, or can +decide to allocate memory for the GEM object at the time the object is +created. + +Drivers that want to map the GEM object upfront instead of handling page +faults can implement their own mmap file operation handler. + +Memory Coherency +~~~~~~~~~~~~~~~~ + +When mapped to the device or used in a command buffer, backing pages for +an object are flushed to memory and marked write combined so as to be +coherent with the GPU. Likewise, if the CPU accesses an object after the +GPU has finished rendering to the object, then the object must be made +coherent with the CPU's view of memory, usually involving GPU cache +flushing of various kinds. This core CPU<->GPU coherency management is +provided by a device-specific ioctl, which evaluates an object's current +domain and performs any necessary flushing or synchronization to put the +object into the desired coherency domain (note that the object may be +busy, i.e. an active render target; in that case, setting the domain +blocks the client and waits for rendering to complete before performing +any necessary flushing operations). + +Command Execution +~~~~~~~~~~~~~~~~~ + +Perhaps the most important GEM function for GPU devices is providing a +command execution interface to clients. Client programs construct +command buffers containing references to previously allocated memory +objects, and then submit them to GEM. At that point, GEM takes care to +bind all the objects into the GTT, execute the buffer, and provide +necessary synchronization between clients accessing the same buffers. +This often involves evicting some objects from the GTT and re-binding +others (a fairly expensive operation), and providing relocation support +which hides fixed GTT offsets from clients. Clients must take care not +to submit command buffers that reference more objects than can fit in +the GTT; otherwise, GEM will reject them and no rendering will occur. +Similarly, if several objects in the buffer require fence registers to +be allocated for correct rendering (e.g. 2D blits on pre-965 chips), +care must be taken not to require more fence registers than are +available to the client. Such resource management should be abstracted +from the client in libdrm. + +GEM Function Reference +---------------------- + +.. kernel-doc:: drivers/gpu/drm/drm_gem.c + :export: + +.. kernel-doc:: include/drm/drm_gem.h + :internal: + +VMA Offset Manager +------------------ + +.. kernel-doc:: drivers/gpu/drm/drm_vma_manager.c + :doc: vma offset manager + +.. kernel-doc:: drivers/gpu/drm/drm_vma_manager.c + :export: + +.. kernel-doc:: include/drm/drm_vma_manager.h + :internal: + +PRIME Buffer Sharing +-------------------- + +PRIME is the cross device buffer sharing framework in drm, originally +created for the OPTIMUS range of multi-gpu platforms. To userspace PRIME +buffers are dma-buf based file descriptors. + +Overview and Driver Interface +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +Similar to GEM global names, PRIME file descriptors are also used to +share buffer objects across processes. They offer additional security: +as file descriptors must be explicitly sent over UNIX domain sockets to +be shared between applications, they can't be guessed like the globally +unique GEM names. + +Drivers that support the PRIME API must set the DRIVER_PRIME bit in the +struct :c:type:`struct drm_driver <drm_driver>` +driver_features field, and implement the prime_handle_to_fd and +prime_fd_to_handle operations. + +int (\*prime_handle_to_fd)(struct drm_device \*dev, struct drm_file +\*file_priv, uint32_t handle, uint32_t flags, int \*prime_fd); int +(\*prime_fd_to_handle)(struct drm_device \*dev, struct drm_file +\*file_priv, int prime_fd, uint32_t \*handle); Those two operations +convert a handle to a PRIME file descriptor and vice versa. Drivers must +use the kernel dma-buf buffer sharing framework to manage the PRIME file +descriptors. Similar to the mode setting API PRIME is agnostic to the +underlying buffer object manager, as long as handles are 32bit unsigned +integers. + +While non-GEM drivers must implement the operations themselves, GEM +drivers must use the :c:func:`drm_gem_prime_handle_to_fd()` and +:c:func:`drm_gem_prime_fd_to_handle()` helper functions. Those +helpers rely on the driver gem_prime_export and gem_prime_import +operations to create a dma-buf instance from a GEM object (dma-buf +exporter role) and to create a GEM object from a dma-buf instance +(dma-buf importer role). + +struct dma_buf \* (\*gem_prime_export)(struct drm_device \*dev, +struct drm_gem_object \*obj, int flags); struct drm_gem_object \* +(\*gem_prime_import)(struct drm_device \*dev, struct dma_buf +\*dma_buf); These two operations are mandatory for GEM drivers that +support PRIME. + +PRIME Helper Functions +~~~~~~~~~~~~~~~~~~~~~~ + +.. kernel-doc:: drivers/gpu/drm/drm_prime.c + :doc: PRIME Helpers + +PRIME Function References +------------------------- + +.. kernel-doc:: drivers/gpu/drm/drm_prime.c + :export: + +DRM MM Range Allocator +---------------------- + +Overview +~~~~~~~~ + +.. kernel-doc:: drivers/gpu/drm/drm_mm.c + :doc: Overview + +LRU Scan/Eviction Support +~~~~~~~~~~~~~~~~~~~~~~~~~ + +.. kernel-doc:: drivers/gpu/drm/drm_mm.c + :doc: lru scan roaster + +DRM MM Range Allocator Function References +------------------------------------------ + +.. kernel-doc:: drivers/gpu/drm/drm_mm.c + :export: + +.. kernel-doc:: include/drm/drm_mm.h + :internal: + +CMA Helper Functions Reference +------------------------------ + +.. kernel-doc:: drivers/gpu/drm/drm_gem_cma_helper.c + :doc: cma helpers + +.. kernel-doc:: drivers/gpu/drm/drm_gem_cma_helper.c + :export: + +.. kernel-doc:: include/drm/drm_gem_cma_helper.h + :internal: diff --git a/Documentation/gpu/drm-uapi.rst b/Documentation/gpu/drm-uapi.rst new file mode 100644 index 000000000000..536bf3eaadd4 --- /dev/null +++ b/Documentation/gpu/drm-uapi.rst @@ -0,0 +1,111 @@ +=================== +Userland interfaces +=================== + +The DRM core exports several interfaces to applications, generally +intended to be used through corresponding libdrm wrapper functions. In +addition, drivers export device-specific interfaces for use by userspace +drivers & device-aware applications through ioctls and sysfs files. + +External interfaces include: memory mapping, context management, DMA +operations, AGP management, vblank control, fence management, memory +management, and output management. + +Cover generic ioctls and sysfs layout here. We only need high-level +info, since man pages should cover the rest. + +libdrm Device Lookup +==================== + +.. kernel-doc:: drivers/gpu/drm/drm_ioctl.c + :doc: getunique and setversion story + + +Primary Nodes, DRM Master and Authentication +============================================ + +.. kernel-doc:: drivers/gpu/drm/drm_auth.c + :doc: master and authentication + +.. kernel-doc:: drivers/gpu/drm/drm_auth.c + :export: + +.. kernel-doc:: include/drm/drm_auth.h + :internal: + +Render nodes +============ + +DRM core provides multiple character-devices for user-space to use. +Depending on which device is opened, user-space can perform a different +set of operations (mainly ioctls). The primary node is always created +and called card<num>. Additionally, a currently unused control node, +called controlD<num> is also created. The primary node provides all +legacy operations and historically was the only interface used by +userspace. With KMS, the control node was introduced. However, the +planned KMS control interface has never been written and so the control +node stays unused to date. + +With the increased use of offscreen renderers and GPGPU applications, +clients no longer require running compositors or graphics servers to +make use of a GPU. But the DRM API required unprivileged clients to +authenticate to a DRM-Master prior to getting GPU access. To avoid this +step and to grant clients GPU access without authenticating, render +nodes were introduced. Render nodes solely serve render clients, that +is, no modesetting or privileged ioctls can be issued on render nodes. +Only non-global rendering commands are allowed. If a driver supports +render nodes, it must advertise it via the DRIVER_RENDER DRM driver +capability. If not supported, the primary node must be used for render +clients together with the legacy drmAuth authentication procedure. + +If a driver advertises render node support, DRM core will create a +separate render node called renderD<num>. There will be one render node +per device. No ioctls except PRIME-related ioctls will be allowed on +this node. Especially GEM_OPEN will be explicitly prohibited. Render +nodes are designed to avoid the buffer-leaks, which occur if clients +guess the flink names or mmap offsets on the legacy interface. +Additionally to this basic interface, drivers must mark their +driver-dependent render-only ioctls as DRM_RENDER_ALLOW so render +clients can use them. Driver authors must be careful not to allow any +privileged ioctls on render nodes. + +With render nodes, user-space can now control access to the render node +via basic file-system access-modes. A running graphics server which +authenticates clients on the privileged primary/legacy node is no longer +required. Instead, a client can open the render node and is immediately +granted GPU access. Communication between clients (or servers) is done +via PRIME. FLINK from render node to legacy node is not supported. New +clients must not use the insecure FLINK interface. + +Besides dropping all modeset/global ioctls, render nodes also drop the +DRM-Master concept. There is no reason to associate render clients with +a DRM-Master as they are independent of any graphics server. Besides, +they must work without any running master, anyway. Drivers must be able +to run without a master object if they support render nodes. If, on the +other hand, a driver requires shared state between clients which is +visible to user-space and accessible beyond open-file boundaries, they +cannot support render nodes. + +VBlank event handling +===================== + +The DRM core exposes two vertical blank related ioctls: + +DRM_IOCTL_WAIT_VBLANK + This takes a struct drm_wait_vblank structure as its argument, and + it is used to block or request a signal when a specified vblank + event occurs. + +DRM_IOCTL_MODESET_CTL + This was only used for user-mode-settind drivers around modesetting + changes to allow the kernel to update the vblank interrupt after + mode setting, since on many devices the vertical blank counter is + reset to 0 at some point during modeset. Modern drivers should not + call this any more since with kernel mode setting it is a no-op. + +This second part of the GPU Driver Developer's Guide documents driver +code, implementation details and also all the driver-specific userspace +interfaces. Especially since all hardware-acceleration interfaces to +userspace are driver specific for efficiency and other reasons these +interfaces can be rather substantial. Hence every driver has its own +chapter. diff --git a/Documentation/gpu/i915.rst b/Documentation/gpu/i915.rst new file mode 100644 index 000000000000..2fe5952e90f1 --- /dev/null +++ b/Documentation/gpu/i915.rst @@ -0,0 +1,347 @@ +=========================== + drm/i915 Intel GFX Driver +=========================== + +The drm/i915 driver supports all (with the exception of some very early +models) integrated GFX chipsets with both Intel display and rendering +blocks. This excludes a set of SoC platforms with an SGX rendering unit, +those have basic support through the gma500 drm driver. + +Core Driver Infrastructure +========================== + +This section covers core driver infrastructure used by both the display +and the GEM parts of the driver. + +Runtime Power Management +------------------------ + +.. kernel-doc:: drivers/gpu/drm/i915/intel_runtime_pm.c + :doc: runtime pm + +.. kernel-doc:: drivers/gpu/drm/i915/intel_runtime_pm.c + :internal: + +.. kernel-doc:: drivers/gpu/drm/i915/intel_uncore.c + :internal: + +Interrupt Handling +------------------ + +.. kernel-doc:: drivers/gpu/drm/i915/i915_irq.c + :doc: interrupt handling + +.. kernel-doc:: drivers/gpu/drm/i915/i915_irq.c + :functions: intel_irq_init intel_irq_init_hw intel_hpd_init + +.. kernel-doc:: drivers/gpu/drm/i915/i915_irq.c + :functions: intel_runtime_pm_disable_interrupts + +.. kernel-doc:: drivers/gpu/drm/i915/i915_irq.c + :functions: intel_runtime_pm_enable_interrupts + +Intel GVT-g Guest Support(vGPU) +------------------------------- + +.. kernel-doc:: drivers/gpu/drm/i915/i915_vgpu.c + :doc: Intel GVT-g guest support + +.. kernel-doc:: drivers/gpu/drm/i915/i915_vgpu.c + :internal: + +Display Hardware Handling +========================= + +This section covers everything related to the display hardware including +the mode setting infrastructure, plane, sprite and cursor handling and +display, output probing and related topics. + +Mode Setting Infrastructure +--------------------------- + +The i915 driver is thus far the only DRM driver which doesn't use the +common DRM helper code to implement mode setting sequences. Thus it has +its own tailor-made infrastructure for executing a display configuration +change. + +Frontbuffer Tracking +-------------------- + +.. kernel-doc:: drivers/gpu/drm/i915/intel_frontbuffer.c + :doc: frontbuffer tracking + +.. kernel-doc:: drivers/gpu/drm/i915/intel_frontbuffer.c + :internal: + +.. kernel-doc:: drivers/gpu/drm/i915/i915_gem.c + :functions: i915_gem_track_fb + +Display FIFO Underrun Reporting +------------------------------- + +.. kernel-doc:: drivers/gpu/drm/i915/intel_fifo_underrun.c + :doc: fifo underrun handling + +.. kernel-doc:: drivers/gpu/drm/i915/intel_fifo_underrun.c + :internal: + +Plane Configuration +------------------- + +This section covers plane configuration and composition with the primary +plane, sprites, cursors and overlays. This includes the infrastructure +to do atomic vsync'ed updates of all this state and also tightly coupled +topics like watermark setup and computation, framebuffer compression and +panel self refresh. + +Atomic Plane Helpers +-------------------- + +.. kernel-doc:: drivers/gpu/drm/i915/intel_atomic_plane.c + :doc: atomic plane helpers + +.. kernel-doc:: drivers/gpu/drm/i915/intel_atomic_plane.c + :internal: + +Output Probing +-------------- + +This section covers output probing and related infrastructure like the +hotplug interrupt storm detection and mitigation code. Note that the +i915 driver still uses most of the common DRM helper code for output +probing, so those sections fully apply. + +Hotplug +------- + +.. kernel-doc:: drivers/gpu/drm/i915/intel_hotplug.c + :doc: Hotplug + +.. kernel-doc:: drivers/gpu/drm/i915/intel_hotplug.c + :internal: + +High Definition Audio +--------------------- + +.. kernel-doc:: drivers/gpu/drm/i915/intel_audio.c + :doc: High Definition Audio over HDMI and Display Port + +.. kernel-doc:: drivers/gpu/drm/i915/intel_audio.c + :internal: + +.. kernel-doc:: include/drm/i915_component.h + :internal: + +Panel Self Refresh PSR (PSR/SRD) +-------------------------------- + +.. kernel-doc:: drivers/gpu/drm/i915/intel_psr.c + :doc: Panel Self Refresh (PSR/SRD) + +.. kernel-doc:: drivers/gpu/drm/i915/intel_psr.c + :internal: + +Frame Buffer Compression (FBC) +------------------------------ + +.. kernel-doc:: drivers/gpu/drm/i915/intel_fbc.c + :doc: Frame Buffer Compression (FBC) + +.. kernel-doc:: drivers/gpu/drm/i915/intel_fbc.c + :internal: + +Display Refresh Rate Switching (DRRS) +------------------------------------- + +.. kernel-doc:: drivers/gpu/drm/i915/intel_dp.c + :doc: Display Refresh Rate Switching (DRRS) + +.. kernel-doc:: drivers/gpu/drm/i915/intel_dp.c + :functions: intel_dp_set_drrs_state + +.. kernel-doc:: drivers/gpu/drm/i915/intel_dp.c + :functions: intel_edp_drrs_enable + +.. kernel-doc:: drivers/gpu/drm/i915/intel_dp.c + :functions: intel_edp_drrs_disable + +.. kernel-doc:: drivers/gpu/drm/i915/intel_dp.c + :functions: intel_edp_drrs_invalidate + +.. kernel-doc:: drivers/gpu/drm/i915/intel_dp.c + :functions: intel_edp_drrs_flush + +.. kernel-doc:: drivers/gpu/drm/i915/intel_dp.c + :functions: intel_dp_drrs_init + +DPIO +---- + +.. kernel-doc:: drivers/gpu/drm/i915/i915_reg.h + :doc: DPIO + +CSR firmware support for DMC +---------------------------- + +.. kernel-doc:: drivers/gpu/drm/i915/intel_csr.c + :doc: csr support for dmc + +.. kernel-doc:: drivers/gpu/drm/i915/intel_csr.c + :internal: + +Video BIOS Table (VBT) +---------------------- + +.. kernel-doc:: drivers/gpu/drm/i915/intel_bios.c + :doc: Video BIOS Table (VBT) + +.. kernel-doc:: drivers/gpu/drm/i915/intel_bios.c + :internal: + +.. kernel-doc:: drivers/gpu/drm/i915/intel_vbt_defs.h + :internal: + +Memory Management and Command Submission +======================================== + +This sections covers all things related to the GEM implementation in the +i915 driver. + +Batchbuffer Parsing +------------------- + +.. kernel-doc:: drivers/gpu/drm/i915/i915_cmd_parser.c + :doc: batch buffer command parser + +.. kernel-doc:: drivers/gpu/drm/i915/i915_cmd_parser.c + :internal: + +Batchbuffer Pools +----------------- + +.. kernel-doc:: drivers/gpu/drm/i915/i915_gem_batch_pool.c + :doc: batch pool + +.. kernel-doc:: drivers/gpu/drm/i915/i915_gem_batch_pool.c + :internal: + +Logical Rings, Logical Ring Contexts and Execlists +-------------------------------------------------- + +.. kernel-doc:: drivers/gpu/drm/i915/intel_lrc.c + :doc: Logical Rings, Logical Ring Contexts and Execlists + +.. kernel-doc:: drivers/gpu/drm/i915/intel_lrc.c + :internal: + +Global GTT views +---------------- + +.. kernel-doc:: drivers/gpu/drm/i915/i915_gem_gtt.c + :doc: Global GTT views + +.. kernel-doc:: drivers/gpu/drm/i915/i915_gem_gtt.c + :internal: + +GTT Fences and Swizzling +------------------------ + +.. kernel-doc:: drivers/gpu/drm/i915/i915_gem_fence.c + :internal: + +Global GTT Fence Handling +~~~~~~~~~~~~~~~~~~~~~~~~~ + +.. kernel-doc:: drivers/gpu/drm/i915/i915_gem_fence.c + :doc: fence register handling + +Hardware Tiling and Swizzling Details +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +.. kernel-doc:: drivers/gpu/drm/i915/i915_gem_fence.c + :doc: tiling swizzling details + +Object Tiling IOCTLs +-------------------- + +.. kernel-doc:: drivers/gpu/drm/i915/i915_gem_tiling.c + :internal: + +.. kernel-doc:: drivers/gpu/drm/i915/i915_gem_tiling.c + :doc: buffer object tiling + +Buffer Object Eviction +---------------------- + +This section documents the interface functions for evicting buffer +objects to make space available in the virtual gpu address spaces. Note +that this is mostly orthogonal to shrinking buffer objects caches, which +has the goal to make main memory (shared with the gpu through the +unified memory architecture) available. + +.. kernel-doc:: drivers/gpu/drm/i915/i915_gem_evict.c + :internal: + +Buffer Object Memory Shrinking +------------------------------ + +This section documents the interface function for shrinking memory usage +of buffer object caches. Shrinking is used to make main memory +available. Note that this is mostly orthogonal to evicting buffer +objects, which has the goal to make space in gpu virtual address spaces. + +.. kernel-doc:: drivers/gpu/drm/i915/i915_gem_shrinker.c + :internal: + +GuC +=== + +GuC-specific firmware loader +---------------------------- + +.. kernel-doc:: drivers/gpu/drm/i915/intel_guc_loader.c + :doc: GuC-specific firmware loader + +.. kernel-doc:: drivers/gpu/drm/i915/intel_guc_loader.c + :internal: + +GuC-based command submission +---------------------------- + +.. kernel-doc:: drivers/gpu/drm/i915/i915_guc_submission.c + :doc: GuC-based command submission + +.. kernel-doc:: drivers/gpu/drm/i915/i915_guc_submission.c + :internal: + +GuC Firmware Layout +------------------- + +.. kernel-doc:: drivers/gpu/drm/i915/intel_guc_fwif.h + :doc: GuC Firmware Layout + +Tracing +======= + +This sections covers all things related to the tracepoints implemented +in the i915 driver. + +i915_ppgtt_create and i915_ppgtt_release +---------------------------------------- + +.. kernel-doc:: drivers/gpu/drm/i915/i915_trace.h + :doc: i915_ppgtt_create and i915_ppgtt_release tracepoints + +i915_context_create and i915_context_free +----------------------------------------- + +.. kernel-doc:: drivers/gpu/drm/i915/i915_trace.h + :doc: i915_context_create and i915_context_free tracepoints + +switch_mm +--------- + +.. kernel-doc:: drivers/gpu/drm/i915/i915_trace.h + :doc: switch_mm tracepoint + +.. WARNING: DOCPROC directive not supported: !Cdrivers/gpu/drm/i915/i915_irq.c diff --git a/Documentation/gpu/index.rst b/Documentation/gpu/index.rst new file mode 100644 index 000000000000..fcac0fa72056 --- /dev/null +++ b/Documentation/gpu/index.rst @@ -0,0 +1,14 @@ +================================== +Linux GPU Driver Developer's Guide +================================== + +.. toctree:: + + introduction + drm-internals + drm-mm + drm-kms + drm-kms-helpers + drm-uapi + i915 + vga-switcheroo diff --git a/Documentation/gpu/introduction.rst b/Documentation/gpu/introduction.rst new file mode 100644 index 000000000000..1903595b5310 --- /dev/null +++ b/Documentation/gpu/introduction.rst @@ -0,0 +1,51 @@ +============ +Introduction +============ + +The Linux DRM layer contains code intended to support the needs of +complex graphics devices, usually containing programmable pipelines well +suited to 3D graphics acceleration. Graphics drivers in the kernel may +make use of DRM functions to make tasks like memory management, +interrupt handling and DMA easier, and provide a uniform interface to +applications. + +A note on versions: this guide covers features found in the DRM tree, +including the TTM memory manager, output configuration and mode setting, +and the new vblank internals, in addition to all the regular features +found in current kernels. + +[Insert diagram of typical DRM stack here] + +Style Guidelines +================ + +For consistency this documentation uses American English. Abbreviations +are written as all-uppercase, for example: DRM, KMS, IOCTL, CRTC, and so +on. To aid in reading, documentations make full use of the markup +characters kerneldoc provides: @parameter for function parameters, +@member for structure members, &structure to reference structures and +function() for functions. These all get automatically hyperlinked if +kerneldoc for the referenced objects exists. When referencing entries in +function vtables please use ->vfunc(). Note that kerneldoc does not +support referencing struct members directly, so please add a reference +to the vtable struct somewhere in the same paragraph or at least +section. + +Except in special situations (to separate locked from unlocked variants) +locking requirements for functions aren't documented in the kerneldoc. +Instead locking should be check at runtime using e.g. +``WARN_ON(!mutex_is_locked(...));``. Since it's much easier to ignore +documentation than runtime noise this provides more value. And on top of +that runtime checks do need to be updated when the locking rules change, +increasing the chances that they're correct. Within the documentation +the locking rules should be explained in the relevant structures: Either +in the comment for the lock explaining what it protects, or data fields +need a note about which lock protects them, or both. + +Functions which have a non-\ ``void`` return value should have a section +called "Returns" explaining the expected return values in different +cases and their meanings. Currently there's no consensus whether that +section name should be all upper-case or not, and whether it should end +in a colon or not. Go with the file-local style. Other common section +names are "Notes" with information for dangerous or tricky corner cases, +and "FIXME" where the interface could be cleaned up. diff --git a/Documentation/gpu/kms-properties.csv b/Documentation/gpu/kms-properties.csv new file mode 100644 index 000000000000..b6fcaf639c04 --- /dev/null +++ b/Documentation/gpu/kms-properties.csv @@ -0,0 +1,128 @@ +Owner Module/Drivers,Group,Property Name,Type,Property Values,Object attached,Description/Restrictions +DRM,Generic,“rotation”,BITMASK,"{ 0, ""rotate-0"" }, { 1, ""rotate-90"" }, { 2, ""rotate-180"" }, { 3, ""rotate-270"" }, { 4, ""reflect-x"" }, { 5, ""reflect-y"" }","CRTC, Plane",rotate-(degrees) rotates the image by the specified amount in degrees in counter clockwise direction. reflect-x and reflect-y reflects the image along the specified axis prior to rotation +,,“scaling mode”,ENUM,"{ ""None"", ""Full"", ""Center"", ""Full aspect"" }",Connector,"Supported by: amdgpu, gma500, i915, nouveau and radeon." +,Connector,“EDID”,BLOB | IMMUTABLE,0,Connector,Contains id of edid blob ptr object. +,,“DPMS”,ENUM,"{ “On”, “Standby”, “Suspend”, “Off” }",Connector,Contains DPMS operation mode value. +,,“PATH”,BLOB | IMMUTABLE,0,Connector,Contains topology path to a connector. +,,“TILE”,BLOB | IMMUTABLE,0,Connector,Contains tiling information for a connector. +,,“CRTC_ID”,OBJECT,DRM_MODE_OBJECT_CRTC,Connector,CRTC that connector is attached to (atomic) +,Plane,“type”,ENUM | IMMUTABLE,"{ ""Overlay"", ""Primary"", ""Cursor"" }",Plane,Plane type +,,“SRC_X”,RANGE,"Min=0, Max=UINT_MAX",Plane,Scanout source x coordinate in 16.16 fixed point (atomic) +,,“SRC_Y”,RANGE,"Min=0, Max=UINT_MAX",Plane,Scanout source y coordinate in 16.16 fixed point (atomic) +,,“SRC_W”,RANGE,"Min=0, Max=UINT_MAX",Plane,Scanout source width in 16.16 fixed point (atomic) +,,“SRC_H”,RANGE,"Min=0, Max=UINT_MAX",Plane,Scanout source height in 16.16 fixed point (atomic) +,,“CRTC_X”,SIGNED_RANGE,"Min=INT_MIN, Max=INT_MAX",Plane,Scanout CRTC (destination) x coordinate (atomic) +,,“CRTC_Y”,SIGNED_RANGE,"Min=INT_MIN, Max=INT_MAX",Plane,Scanout CRTC (destination) y coordinate (atomic) +,,“CRTC_W”,RANGE,"Min=0, Max=UINT_MAX",Plane,Scanout CRTC (destination) width (atomic) +,,“CRTC_H”,RANGE,"Min=0, Max=UINT_MAX",Plane,Scanout CRTC (destination) height (atomic) +,,“FB_ID”,OBJECT,DRM_MODE_OBJECT_FB,Plane,Scanout framebuffer (atomic) +,,“CRTC_ID”,OBJECT,DRM_MODE_OBJECT_CRTC,Plane,CRTC that plane is attached to (atomic) +,DVI-I,“subconnector”,ENUM,"{ “Unknown”, “DVI-D”, “DVI-A” }",Connector,TBD +,,“select subconnector”,ENUM,"{ “Automatic”, “DVI-D”, “DVI-A” }",Connector,TBD +,TV,“subconnector”,ENUM,"{ ""Unknown"", ""Composite"", ""SVIDEO"", ""Component"", ""SCART"" }",Connector,TBD +,,“select subconnector”,ENUM,"{ ""Automatic"", ""Composite"", ""SVIDEO"", ""Component"", ""SCART"" }",Connector,TBD +,,“mode”,ENUM,"{ ""NTSC_M"", ""NTSC_J"", ""NTSC_443"", ""PAL_B"" } etc.",Connector,TBD +,,“left margin”,RANGE,"Min=0, Max=100",Connector,TBD +,,“right margin”,RANGE,"Min=0, Max=100",Connector,TBD +,,“top margin”,RANGE,"Min=0, Max=100",Connector,TBD +,,“bottom margin”,RANGE,"Min=0, Max=100",Connector,TBD +,,“brightness”,RANGE,"Min=0, Max=100",Connector,TBD +,,“contrast”,RANGE,"Min=0, Max=100",Connector,TBD +,,“flicker reduction”,RANGE,"Min=0, Max=100",Connector,TBD +,,“overscan”,RANGE,"Min=0, Max=100",Connector,TBD +,,“saturation”,RANGE,"Min=0, Max=100",Connector,TBD +,,“hue”,RANGE,"Min=0, Max=100",Connector,TBD +,Virtual GPU,“suggested X”,RANGE,"Min=0, Max=0xffffffff",Connector,property to suggest an X offset for a connector +,,“suggested Y”,RANGE,"Min=0, Max=0xffffffff",Connector,property to suggest an Y offset for a connector +,Optional,"""aspect ratio""",ENUM,"{ ""None"", ""4:3"", ""16:9"" }",Connector,TDB +,,“dirty”,ENUM | IMMUTABLE,"{ ""Off"", ""On"", ""Annotate"" }",Connector,TBD +,,“DEGAMMA_LUT”,BLOB,0,CRTC,DRM property to set the degamma lookup table (LUT) mapping pixel data from the framebuffer before it is given to the transformation matrix. The data is an interpreted as an array of struct drm_color_lut elements. Hardware might choose not to use the full precision of the LUT elements nor use all the elements of the LUT (for example the hardware might choose to interpolate between LUT[0] and LUT[4]). +,,“DEGAMMA_LUT_SIZE”,RANGE | IMMUTABLE,"Min=0, Max=UINT_MAX",CRTC,DRM property to gives the size of the lookup table to be set on the DEGAMMA_LUT property (the size depends on the underlying hardware). +,,“CTM”,BLOB,0,CRTC,DRM property to set the current transformation matrix (CTM) apply to pixel data after the lookup through the degamma LUT and before the lookup through the gamma LUT. The data is an interpreted as a struct drm_color_ctm. +,,“GAMMA_LUT”,BLOB,0,CRTC,DRM property to set the gamma lookup table (LUT) mapping pixel data after to the transformation matrix to data sent to the connector. The data is an interpreted as an array of struct drm_color_lut elements. Hardware might choose not to use the full precision of the LUT elements nor use all the elements of the LUT (for example the hardware might choose to interpolate between LUT[0] and LUT[4]). +,,“GAMMA_LUT_SIZE”,RANGE | IMMUTABLE,"Min=0, Max=UINT_MAX",CRTC,DRM property to gives the size of the lookup table to be set on the GAMMA_LUT property (the size depends on the underlying hardware). +i915,Generic,"""Broadcast RGB""",ENUM,"{ ""Automatic"", ""Full"", ""Limited 16:235"" }",Connector,"When this property is set to Limited 16:235 and CTM is set, the hardware will be programmed with the result of the multiplication of CTM by the limited range matrix to ensure the pixels normaly in the range 0..1.0 are remapped to the range 16/255..235/255." +,,“audio”,ENUM,"{ ""force-dvi"", ""off"", ""auto"", ""on"" }",Connector,TBD +,SDVO-TV,“mode”,ENUM,"{ ""NTSC_M"", ""NTSC_J"", ""NTSC_443"", ""PAL_B"" } etc.",Connector,TBD +,,"""left_margin""",RANGE,"Min=0, Max= SDVO dependent",Connector,TBD +,,"""right_margin""",RANGE,"Min=0, Max= SDVO dependent",Connector,TBD +,,"""top_margin""",RANGE,"Min=0, Max= SDVO dependent",Connector,TBD +,,"""bottom_margin""",RANGE,"Min=0, Max= SDVO dependent",Connector,TBD +,,“hpos”,RANGE,"Min=0, Max= SDVO dependent",Connector,TBD +,,“vpos”,RANGE,"Min=0, Max= SDVO dependent",Connector,TBD +,,“contrast”,RANGE,"Min=0, Max= SDVO dependent",Connector,TBD +,,“saturation”,RANGE,"Min=0, Max= SDVO dependent",Connector,TBD +,,“hue”,RANGE,"Min=0, Max= SDVO dependent",Connector,TBD +,,“sharpness”,RANGE,"Min=0, Max= SDVO dependent",Connector,TBD +,,“flicker_filter”,RANGE,"Min=0, Max= SDVO dependent",Connector,TBD +,,“flicker_filter_adaptive”,RANGE,"Min=0, Max= SDVO dependent",Connector,TBD +,,“flicker_filter_2d”,RANGE,"Min=0, Max= SDVO dependent",Connector,TBD +,,“tv_chroma_filter”,RANGE,"Min=0, Max= SDVO dependent",Connector,TBD +,,“tv_luma_filter”,RANGE,"Min=0, Max= SDVO dependent",Connector,TBD +,,“dot_crawl”,RANGE,"Min=0, Max=1",Connector,TBD +,SDVO-TV/LVDS,“brightness”,RANGE,"Min=0, Max= SDVO dependent",Connector,TBD +CDV gma-500,Generic,"""Broadcast RGB""",ENUM,"{ “Full”, “Limited 16:235” }",Connector,TBD +,,"""Broadcast RGB""",ENUM,"{ “off”, “auto”, “on” }",Connector,TBD +Poulsbo,Generic,“backlight”,RANGE,"Min=0, Max=100",Connector,TBD +,SDVO-TV,“mode”,ENUM,"{ ""NTSC_M"", ""NTSC_J"", ""NTSC_443"", ""PAL_B"" } etc.",Connector,TBD +,,"""left_margin""",RANGE,"Min=0, Max= SDVO dependent",Connector,TBD +,,"""right_margin""",RANGE,"Min=0, Max= SDVO dependent",Connector,TBD +,,"""top_margin""",RANGE,"Min=0, Max= SDVO dependent",Connector,TBD +,,"""bottom_margin""",RANGE,"Min=0, Max= SDVO dependent",Connector,TBD +,,“hpos”,RANGE,"Min=0, Max= SDVO dependent",Connector,TBD +,,“vpos”,RANGE,"Min=0, Max= SDVO dependent",Connector,TBD +,,“contrast”,RANGE,"Min=0, Max= SDVO dependent",Connector,TBD +,,“saturation”,RANGE,"Min=0, Max= SDVO dependent",Connector,TBD +,,“hue”,RANGE,"Min=0, Max= SDVO dependent",Connector,TBD +,,“sharpness”,RANGE,"Min=0, Max= SDVO dependent",Connector,TBD +,,“flicker_filter”,RANGE,"Min=0, Max= SDVO dependent",Connector,TBD +,,“flicker_filter_adaptive”,RANGE,"Min=0, Max= SDVO dependent",Connector,TBD +,,“flicker_filter_2d”,RANGE,"Min=0, Max= SDVO dependent",Connector,TBD +,,“tv_chroma_filter”,RANGE,"Min=0, Max= SDVO dependent",Connector,TBD +,,“tv_luma_filter”,RANGE,"Min=0, Max= SDVO dependent",Connector,TBD +,,“dot_crawl”,RANGE,"Min=0, Max=1",Connector,TBD +,SDVO-TV/LVDS,“brightness”,RANGE,"Min=0, Max= SDVO dependent",Connector,TBD +armada,CRTC,"""CSC_YUV""",ENUM,"{ ""Auto"" , ""CCIR601"", ""CCIR709"" }",CRTC,TBD +,,"""CSC_RGB""",ENUM,"{ ""Auto"", ""Computer system"", ""Studio"" }",CRTC,TBD +,Overlay,"""colorkey""",RANGE,"Min=0, Max=0xffffff",Plane,TBD +,,"""colorkey_min""",RANGE,"Min=0, Max=0xffffff",Plane,TBD +,,"""colorkey_max""",RANGE,"Min=0, Max=0xffffff",Plane,TBD +,,"""colorkey_val""",RANGE,"Min=0, Max=0xffffff",Plane,TBD +,,"""colorkey_alpha""",RANGE,"Min=0, Max=0xffffff",Plane,TBD +,,"""colorkey_mode""",ENUM,"{ ""disabled"", ""Y component"", ""U component"" , ""V component"", ""RGB"", “R component"", ""G component"", ""B component"" }",Plane,TBD +,,"""brightness""",RANGE,"Min=0, Max=256 + 255",Plane,TBD +,,"""contrast""",RANGE,"Min=0, Max=0x7fff",Plane,TBD +,,"""saturation""",RANGE,"Min=0, Max=0x7fff",Plane,TBD +exynos,CRTC,“mode”,ENUM,"{ ""normal"", ""blank"" }",CRTC,TBD +,Overlay,“zpos”,RANGE,"Min=0, Max=MAX_PLANE-1",Plane,TBD +i2c/ch7006_drv,Generic,“scale”,RANGE,"Min=0, Max=2",Connector,TBD +,TV,“mode”,ENUM,"{ ""PAL"", ""PAL-M"",""PAL-N""}, ”PAL-Nc"" , ""PAL-60"", ""NTSC-M"", ""NTSC-J"" }",Connector,TBD +nouveau,NV10 Overlay,"""colorkey""",RANGE,"Min=0, Max=0x01ffffff",Plane,TBD +,,“contrast”,RANGE,"Min=0, Max=8192-1",Plane,TBD +,,“brightness”,RANGE,"Min=0, Max=1024",Plane,TBD +,,“hue”,RANGE,"Min=0, Max=359",Plane,TBD +,,“saturation”,RANGE,"Min=0, Max=8192-1",Plane,TBD +,,“iturbt_709”,RANGE,"Min=0, Max=1",Plane,TBD +,Nv04 Overlay,“colorkey”,RANGE,"Min=0, Max=0x01ffffff",Plane,TBD +,,“brightness”,RANGE,"Min=0, Max=1024",Plane,TBD +,Display,“dithering mode”,ENUM,"{ ""auto"", ""off"", ""on"" }",Connector,TBD +,,“dithering depth”,ENUM,"{ ""auto"", ""off"", ""on"", ""static 2x2"", ""dynamic 2x2"", ""temporal"" }",Connector,TBD +,,“underscan”,ENUM,"{ ""auto"", ""6 bpc"", ""8 bpc"" }",Connector,TBD +,,“underscan hborder”,RANGE,"Min=0, Max=128",Connector,TBD +,,“underscan vborder”,RANGE,"Min=0, Max=128",Connector,TBD +,,“vibrant hue”,RANGE,"Min=0, Max=180",Connector,TBD +,,“color vibrance”,RANGE,"Min=0, Max=200",Connector,TBD +omap,Generic,“zorder”,RANGE,"Min=0, Max=3","CRTC, Plane",TBD +qxl,Generic,"“hotplug_mode_update""",RANGE,"Min=0, Max=1",Connector,TBD +radeon,DVI-I,“coherent”,RANGE,"Min=0, Max=1",Connector,TBD +,DAC enable load detect,“load detection”,RANGE,"Min=0, Max=1",Connector,TBD +,TV Standard,"""tv standard""",ENUM,"{ ""ntsc"", ""pal"", ""pal-m"", ""pal-60"", ""ntsc-j"" , ""scart-pal"", ""pal-cn"", ""secam"" }",Connector,TBD +,legacy TMDS PLL detect,"""tmds_pll""",ENUM,"{ ""driver"", ""bios"" }",-,TBD +,Underscan,"""underscan""",ENUM,"{ ""off"", ""on"", ""auto"" }",Connector,TBD +,,"""underscan hborder""",RANGE,"Min=0, Max=128",Connector,TBD +,,"""underscan vborder""",RANGE,"Min=0, Max=128",Connector,TBD +,Audio,“audio”,ENUM,"{ ""off"", ""on"", ""auto"" }",Connector,TBD +,FMT Dithering,“dither”,ENUM,"{ ""off"", ""on"" }",Connector,TBD +rcar-du,Generic,"""alpha""",RANGE,"Min=0, Max=255",Plane,TBD +,,"""colorkey""",RANGE,"Min=0, Max=0x01ffffff",Plane,TBD +,,"""zpos""",RANGE,"Min=1, Max=7",Plane,TBD diff --git a/Documentation/gpu/vga-switcheroo.rst b/Documentation/gpu/vga-switcheroo.rst new file mode 100644 index 000000000000..327d930a2229 --- /dev/null +++ b/Documentation/gpu/vga-switcheroo.rst @@ -0,0 +1,102 @@ +============== +VGA Switcheroo +============== + +.. kernel-doc:: drivers/gpu/vga/vga_switcheroo.c + :doc: Overview + +Modes of Use +============ + +Manual switching and manual power control +----------------------------------------- + +.. kernel-doc:: drivers/gpu/vga/vga_switcheroo.c + :doc: Manual switching and manual power control + +Driver power control +-------------------- + +.. kernel-doc:: drivers/gpu/vga/vga_switcheroo.c + :doc: Driver power control + +API +=== + +Public functions +---------------- + +.. kernel-doc:: drivers/gpu/vga/vga_switcheroo.c + :export: + +Public structures +----------------- + +.. kernel-doc:: include/linux/vga_switcheroo.h + :functions: vga_switcheroo_handler + +.. kernel-doc:: include/linux/vga_switcheroo.h + :functions: vga_switcheroo_client_ops + +Public constants +---------------- + +.. kernel-doc:: include/linux/vga_switcheroo.h + :functions: vga_switcheroo_handler_flags_t + +.. kernel-doc:: include/linux/vga_switcheroo.h + :functions: vga_switcheroo_client_id + +.. kernel-doc:: include/linux/vga_switcheroo.h + :functions: vga_switcheroo_state + +Private structures +------------------ + +.. kernel-doc:: drivers/gpu/vga/vga_switcheroo.c + :functions: vgasr_priv + +.. kernel-doc:: drivers/gpu/vga/vga_switcheroo.c + :functions: vga_switcheroo_client + +Handlers +======== + +apple-gmux Handler +------------------ + +.. kernel-doc:: drivers/platform/x86/apple-gmux.c + :doc: Overview + +.. kernel-doc:: drivers/platform/x86/apple-gmux.c + :doc: Interrupt + +Graphics mux +~~~~~~~~~~~~ + +.. kernel-doc:: drivers/platform/x86/apple-gmux.c + :doc: Graphics mux + +Power control +~~~~~~~~~~~~~ + +.. kernel-doc:: drivers/platform/x86/apple-gmux.c + :doc: Power control + +Backlight control +~~~~~~~~~~~~~~~~~ + +.. kernel-doc:: drivers/platform/x86/apple-gmux.c + :doc: Backlight control + +Public functions +~~~~~~~~~~~~~~~~ + +.. kernel-doc:: include/linux/apple-gmux.h + :internal: + +.. WARNING: DOCPROC directive not supported: !Cdrivers/gpu/vga/vga_switcheroo.c + +.. WARNING: DOCPROC directive not supported: !Cinclude/linux/vga_switcheroo.h + +.. WARNING: DOCPROC directive not supported: !Cdrivers/platform/x86/apple-gmux.c diff --git a/Documentation/index.rst b/Documentation/index.rst new file mode 100644 index 000000000000..dacc77b43c29 --- /dev/null +++ b/Documentation/index.rst @@ -0,0 +1,24 @@ +.. The Linux Kernel documentation master file, created by + sphinx-quickstart on Fri Feb 12 13:51:46 2016. + You can adapt this file completely to your liking, but it should at least + contain the root `toctree` directive. + +Welcome to The Linux Kernel's documentation! +============================================ + +Nothing for you to see here *yet*. Please move along. + +Contents: + +.. toctree:: + :maxdepth: 2 + + gpu/index + +Indices and tables +================== + +* :ref:`genindex` +* :ref:`modindex` +* :ref:`search` + diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 82b42c958d1c..a2a662d4da83 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -3992,8 +3992,9 @@ bytes respectively. Such letter suffixes can also be entirely omitted. trace_event=[event-list] [FTRACE] Set and start specified trace events in order - to facilitate early boot debugging. - See also Documentation/trace/events.txt + to facilitate early boot debugging. The event-list is a + comma separated list of trace events to enable. See + also Documentation/trace/events.txt trace_options=[option-list] [FTRACE] Enable or disable tracer options at boot. diff --git a/Documentation/mic/mpssd/mpssd.c b/Documentation/mic/mpssd/mpssd.c index 30fb842a976d..49db1def1721 100644 --- a/Documentation/mic/mpssd/mpssd.c +++ b/Documentation/mic/mpssd/mpssd.c @@ -1538,9 +1538,9 @@ set_cmdline(struct mic_info *mic) len = snprintf(buffer, PATH_MAX, "clocksource=tsc highres=off nohz=off "); - len += snprintf(buffer + len, PATH_MAX, + len += snprintf(buffer + len, PATH_MAX - len, "cpufreq_on;corec6_off;pc3_off;pc6_off "); - len += snprintf(buffer + len, PATH_MAX, + len += snprintf(buffer + len, PATH_MAX - len, "ifcfg=static;address,172.31.%d.1;netmask,255.255.255.0", mic->id + 1); diff --git a/Documentation/security/self-protection.txt b/Documentation/security/self-protection.txt index babd6378ec05..3010576c9fca 100644 --- a/Documentation/security/self-protection.txt +++ b/Documentation/security/self-protection.txt @@ -183,8 +183,9 @@ provide meaningful defenses. ### Canaries, blinding, and other secrets It should be noted that things like the stack canary discussed earlier -are technically statistical defenses, since they rely on a (leakable) -secret value. +are technically statistical defenses, since they rely on a secret value, +and such values may become discoverable through an information exposure +flaw. Blinding literal values for things like JITs, where the executable contents may be partially under the control of userspace, need a similar @@ -199,8 +200,8 @@ working?) in order to maximize their success. Since the location of kernel memory is almost always instrumental in mounting a successful attack, making the location non-deterministic raises the difficulty of an exploit. (Note that this in turn makes -the value of leaks higher, since they may be used to discover desired -memory locations.) +the value of information exposures higher, since they may be used to +discover desired memory locations.) #### Text and module base @@ -222,14 +223,21 @@ become more difficult to locate. Much of the kernel's dynamic memory (e.g. kmalloc, vmalloc, etc) ends up being relatively deterministic in layout due to the order of early-boot initializations. If the base address of these areas is not the same -between boots, targeting them is frustrated, requiring a leak specific -to the region. +between boots, targeting them is frustrated, requiring an information +exposure specific to the region. + +#### Structure layout + +By performing a per-build randomization of the layout of sensitive +structures, attacks must either be tuned to known kernel builds or expose +enough kernel memory to determine structure layouts before manipulating +them. -## Preventing Leaks +## Preventing Information Exposures Since the locations of sensitive structures are the primary target for -attacks, it is important to defend against leaks of both kernel memory +attacks, it is important to defend against exposure of both kernel memory addresses and kernel memory contents (since they may contain kernel addresses or other sensitive things like canary values). @@ -250,8 +258,8 @@ sure structure holes are cleared. When releasing memory, it is best to poison the contents (clear stack on syscall return, wipe heap memory on a free), to avoid reuse attacks that rely on the old contents of memory. This frustrates many uninitialized -variable attacks, stack info leaks, heap info leaks, and use-after-free -attacks. +variable attacks, stack content exposures, heap content exposures, and +use-after-free attacks. ### Destination tracking diff --git a/Documentation/sphinx/convert_template.sed b/Documentation/sphinx/convert_template.sed new file mode 100644 index 000000000000..c1503fcca4ec --- /dev/null +++ b/Documentation/sphinx/convert_template.sed @@ -0,0 +1,18 @@ +# +# Pandoc doesn't grok <function> or <structname>, so convert them +# ahead of time. +# +# Use the following escapes to pass through pandoc: +# $bq = "`" +# $lt = "<" +# $gt = ">" +# +s%<function>\([^<(]\+\)()</function>%:c:func:$bq\1()$bq%g +s%<function>\([^<(]\+\)</function>%:c:func:$bq\1()$bq%g +s%<structname>struct *\([^<]\+\)</structname>%:c:type:$bqstruct \1 $lt\1$gt$bq%g +s%struct <structname>\([^<]\+\)</structname>%:c:type:$bqstruct \1 $lt\1$gt$bq%g +s%<structname>\([^<]\+\)</structname>%:c:type:$bqstruct \1 $lt\1$gt$bq%g +# +# Wrap docproc directives in para and code blocks. +# +s%^\(!.*\)$%<para><code>DOCPROC: \1</code></para>% diff --git a/Documentation/sphinx/kernel-doc.py b/Documentation/sphinx/kernel-doc.py new file mode 100644 index 000000000000..4adfb0e91ecc --- /dev/null +++ b/Documentation/sphinx/kernel-doc.py @@ -0,0 +1,127 @@ +# coding=utf-8 +# +# Copyright © 2016 Intel Corporation +# +# Permission is hereby granted, free of charge, to any person obtaining a +# copy of this software and associated documentation files (the "Software"), +# to deal in the Software without restriction, including without limitation +# the rights to use, copy, modify, merge, publish, distribute, sublicense, +# and/or sell copies of the Software, and to permit persons to whom the +# Software is furnished to do so, subject to the following conditions: +# +# The above copyright notice and this permission notice (including the next +# paragraph) shall be included in all copies or substantial portions of the +# Software. +# +# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR +# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, +# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL +# THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER +# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING +# FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS +# IN THE SOFTWARE. +# +# Authors: +# Jani Nikula <jani.nikula@intel.com> +# +# Please make sure this works on both python2 and python3. +# + +import os +import subprocess +import sys +import re + +from docutils import nodes, statemachine +from docutils.statemachine import ViewList +from docutils.parsers.rst import directives +from sphinx.util.compat import Directive + +class KernelDocDirective(Directive): + """Extract kernel-doc comments from the specified file""" + required_argument = 1 + optional_arguments = 4 + option_spec = { + 'doc': directives.unchanged_required, + 'functions': directives.unchanged_required, + 'export': directives.flag, + 'internal': directives.flag, + } + has_content = False + + def run(self): + env = self.state.document.settings.env + cmd = [env.config.kerneldoc_bin, '-rst', '-enable-lineno'] + + filename = env.config.kerneldoc_srctree + '/' + self.arguments[0] + + # Tell sphinx of the dependency + env.note_dependency(os.path.abspath(filename)) + + tab_width = self.options.get('tab-width', self.state.document.settings.tab_width) + source = filename + + # FIXME: make this nicer and more robust against errors + if 'export' in self.options: + cmd += ['-export'] + elif 'internal' in self.options: + cmd += ['-internal'] + elif 'doc' in self.options: + cmd += ['-function', str(self.options.get('doc'))] + elif 'functions' in self.options: + for f in str(self.options.get('functions')).split(' '): + cmd += ['-function', f] + + cmd += [filename] + + try: + env.app.verbose('calling kernel-doc \'%s\'' % (" ".join(cmd))) + + p = subprocess.Popen(cmd, stdout=subprocess.PIPE, stderr=subprocess.PIPE, universal_newlines=True) + out, err = p.communicate() + + # python2 needs conversion to unicode. + # python3 with universal_newlines=True returns strings. + if sys.version_info.major < 3: + out, err = unicode(out, 'utf-8'), unicode(err, 'utf-8') + + if p.returncode != 0: + sys.stderr.write(err) + + env.app.warn('kernel-doc \'%s\' failed with return code %d' % (" ".join(cmd), p.returncode)) + return [nodes.error(None, nodes.paragraph(text = "kernel-doc missing"))] + elif env.config.kerneldoc_verbosity > 0: + sys.stderr.write(err) + + lines = statemachine.string2lines(out, tab_width, convert_whitespace=True) + result = ViewList() + + lineoffset = 0; + line_regex = re.compile("^#define LINENO ([0-9]+)$") + for line in lines: + match = line_regex.search(line) + if match: + # sphinx counts lines from 0 + lineoffset = int(match.group(1)) - 1 + # we must eat our comments since the upset the markup + else: + result.append(line, source, lineoffset) + lineoffset += 1 + + node = nodes.section() + node.document = self.state.document + self.state.nested_parse(result, self.content_offset, node) + + return node.children + + except Exception as e: + env.app.warn('kernel-doc \'%s\' processing failed with: %s' % + (" ".join(cmd), str(e))) + return [nodes.error(None, nodes.paragraph(text = "kernel-doc missing"))] + +def setup(app): + app.add_config_value('kerneldoc_bin', None, 'env') + app.add_config_value('kerneldoc_srctree', None, 'env') + app.add_config_value('kerneldoc_verbosity', 1, 'env') + + app.add_directive('kernel-doc', KernelDocDirective) diff --git a/Documentation/sphinx/post_convert.sed b/Documentation/sphinx/post_convert.sed new file mode 100644 index 000000000000..392770bac53b --- /dev/null +++ b/Documentation/sphinx/post_convert.sed @@ -0,0 +1,23 @@ +# +# Unescape. +# +s/$bq/`/g +s/$lt/</g +s/$gt/>/g +# +# pandoc thinks that both "_" needs to be escaped. Remove the extra +# backslashes. +# +s/\\_/_/g +# +# Unwrap docproc directives. +# +s/^``DOCPROC: !E\(.*\)``$/.. kernel-doc:: \1\n :export:/ +s/^``DOCPROC: !I\(.*\)``$/.. kernel-doc:: \1\n :internal:/ +s/^``DOCPROC: !F\([^ ]*\) \(.*\)``$/.. kernel-doc:: \1\n :functions: \2/ +s/^``DOCPROC: !P\([^ ]*\) \(.*\)``$/.. kernel-doc:: \1\n :doc: \2/ +s/^``DOCPROC: \(!.*\)``$/.. WARNING: DOCPROC directive not supported: \1/ +# +# Trim trailing whitespace. +# +s/[[:space:]]*$// diff --git a/Documentation/sphinx/tmplcvt b/Documentation/sphinx/tmplcvt new file mode 100755 index 000000000000..909a73065e0a --- /dev/null +++ b/Documentation/sphinx/tmplcvt @@ -0,0 +1,19 @@ +#!/bin/bash +# +# Convert a template file into something like RST +# +# fix <function> +# feed to pandoc +# fix \_ +# title line? +# + +in=$1 +rst=$2 +tmp=$rst.tmp + +cp $in $tmp +sed --in-place -f convert_template.sed $tmp +pandoc -s -S -f docbook -t rst -o $rst $tmp +sed --in-place -f post_convert.sed $rst +rm $tmp diff --git a/Documentation/sync_file.txt b/Documentation/sync_file.txt index eaf8297dbca2..e8e2ebafe5fa 100644 --- a/Documentation/sync_file.txt +++ b/Documentation/sync_file.txt @@ -6,8 +6,8 @@ This document serves as a guide for device drivers writers on what the sync_file API is, and how drivers can support it. Sync file is the carrier of -the fences(struct fence) that needs to synchronized between drivers or across -process boundaries. +the fences(struct fence) that are needed to synchronize between drivers or +across process boundaries. The sync_file API is meant to be used to send and receive fence information to/from userspace. It enables userspace to do explicit fencing, where instead @@ -32,7 +32,7 @@ in-fences and out-fences Sync files can go either to or from userspace. When a sync_file is sent from the driver to userspace we call the fences it contains 'out-fences'. They are related to a buffer that the driver is processing or is going to process, so -the driver an create out-fence to be able to notify, through fence_signal(), +the driver creates an out-fence to be able to notify, through fence_signal(), when it has finished using (or processing) that buffer. Out-fences are fences that the driver creates. diff --git a/Documentation/zh_CN/CodingStyle b/Documentation/zh_CN/CodingStyle index 654afd72eb24..bbb9d6ae05ca 100644 --- a/Documentation/zh_CN/CodingStyle +++ b/Documentation/zh_CN/CodingStyle @@ -24,34 +24,33 @@ Documentation/CodingStyle的中文翻译 Linux内核代码风格 -这是一个简短的文档，描述了linux内核的首选代码风格。代码风格是因人而异的，而且我 -不愿意把我的观点强加给任何人，不过这里所讲述的是我必须要维护的代码所遵守的风格， -并且我也希望绝大多数其他代码也能遵守这个风格。请在写代码时至少考虑一下本文所述的 -风格。 +这是一个简短的文档，描述了 linux 内核的首选代码风格。代码风格是因人而异的，而且我 +不愿意把自己的观点强加给任何人，但这就像我去做任何事情都必须遵循的原则那样，我也 +希望在绝大多数事上保持这种的态度。请（在写代码时）至少考虑一下这里的代码风格。 -首先，我建议你打印一份GNU代码规范，然后不要读它。烧了它，这是一个具有重大象征性 -意义的动作。 +首先，我建议你打印一份 GNU 代码规范，然后不要读。烧了它，这是一个具有重大象征性意义 +的动作。 不管怎样，现在我们开始： - 第一章：缩进 + 第一章：缩进 -制表符是8个字符，所以缩进也是8个字符。有些异端运动试图将缩进变为4（乃至2）个字符 -深，这几乎相当于尝试将圆周率的值定义为3。 +制表符是 8 个字符，所以缩进也是 8 个字符。有些异端运动试图将缩进变为 4（甚至 2！） +个字符深，这几乎相当于尝试将圆周率的值定义为 3。 理由：缩进的全部意义就在于清楚的定义一个控制块起止于何处。尤其是当你盯着你的屏幕 -连续看了20小时之后，你将会发现大一点的缩进会使你更容易分辨缩进。 +连续看了 20 小时之后，你将会发现大一点的缩进会使你更容易分辨缩进。 -现在，有些人会抱怨8个字符的缩进会使代码向右边移动的太远，在80个字符的终端屏幕上 -就很难读这样的代码。这个问题的答案是，如果你需要3级以上的缩进，不管用何种方式你 +现在，有些人会抱怨 8 个字符的缩进会使代码向右边移动的太远，在 80 个字符的终端屏幕上 +就很难读这样的代码。这个问题的答案是，如果你需要 3 级以上的缩进，不管用何种方式你 的代码已经有问题了，应该修正你的程序。 -简而言之，8个字符的缩进可以让代码更容易阅读，还有一个好处是当你的函数嵌套太深的 +简而言之，8 个字符的缩进可以让代码更容易阅读，还有一个好处是当你的函数嵌套太深的 时候可以给你警告。留心这个警告。 -在switch语句中消除多级缩进的首选的方式是让“switch”和从属于它的“case”标签对齐于同 -一列，而不要“两次缩进”“case”标签。比如： +在 switch 语句中消除多级缩进的首选的方式是让 “switch” 和从属于它的 “case” 标签 +对齐于同一列，而不要 “两次缩进” “case” 标签。比如： switch (suffix) { case 'G': @@ -70,7 +69,6 @@ Documentation/CodingStyle的中文翻译 break; } - 不要把多个语句放在一行里，除非你有什么东西要隐藏： if (condition) do_this; @@ -79,7 +77,7 @@ Documentation/CodingStyle的中文翻译 也不要在一行里放多个赋值语句。内核代码风格超级简单。就是避免可能导致别人误读的表 达式。 -除了注释、文档和Kconfig之外，不要使用空格来缩进，前面的例子是例外，是有意为之。 +除了注释、文档和 Kconfig 之外，不要使用空格来缩进，前面的例子是例外，是有意为之。 选用一个好的编辑器，不要在行尾留空格。 @@ -88,27 +86,18 @@ Documentation/CodingStyle的中文翻译 代码风格的意义就在于使用平常使用的工具来维持代码的可读性和可维护性。 -每一行的长度的限制是80列，我们强烈建议您遵守这个惯例。 +每一行的长度的限制是 80 列，我们强烈建议您遵守这个惯例。 -长于80列的语句要打散成有意义的片段。每个片段要明显短于原来的语句，而且放置的位置 -也明显的靠右。同样的规则也适用于有很长参数列表的函数头。长字符串也要打散成较短的 -字符串。唯一的例外是超过80列可以大幅度提高可读性并且不会隐藏信息的情况。 - -void fun(int a, int b, int c) -{ - if (condition) - printk(KERN_WARNING "Warning this is a long printk with " - "3 parameters a: %u b: %u " - "c: %u \n", a, b, c); - else - next_statement; -} +长于 80 列的语句要打散成有意义的片段。除非超过 80 列能显著增加可读性，并且不会隐藏 +信息。子片段要明显短于母片段，并明显靠右。这同样适用于有着很长参数列表的函数头。 +然而，绝对不要打散对用户可见的字符串，例如 printk 信息，因为这将导致无法 grep 这些 +信息。 第三章：大括号和空格的放置 C语言风格中另外一个常见问题是大括号的放置。和缩进大小不同，选择或弃用某种放置策 -略并没有多少技术上的原因，不过首选的方式，就像Kernighan和Ritchie展示给我们的，是 -把起始大括号放在行尾，而把结束大括号放在行首，所以： +略并没有多少技术上的原因，不过首选的方式，就像 Kernighan 和 Ritchie 展示给我们的， +是把起始大括号放在行尾，而把结束大括号放在行首，所以： if (x is true) { we do y @@ -134,12 +123,12 @@ C语言风格中另外一个常见问题是大括号的放置。和缩进大小 body of function } -全世界的异端可能会抱怨这个不一致性是……呃……不一致的，不过所有思维健全的人都知道（ -a）K&R是_正确的_，并且（b）K&R是正确的。此外，不管怎样函数都是特殊的（在C语言中 -，函数是不能嵌套的）。 +全世界的异端可能会抱怨这个不一致性是……呃……不一致的，不过所有思维健全的人都知道 +(a) K&R 是 _正确的_，并且 (b) K&R 是正确的。此外，不管怎样函数都是特殊的（C +函数是不能嵌套的）。 -注意结束大括号独自占据一行，除非它后面跟着同一个语句的剩余部分，也就是do语句中的 -“while”或者if语句中的“else”，像这样： +注意结束大括号独自占据一行，除非它后面跟着同一个语句的剩余部分，也就是 do 语句中的 +“while” 或者 if 语句中的 “else”，像这样： do { body of do-loop @@ -158,41 +147,50 @@ a）K&R是_正确的_，并且（b）K&R是正确的。此外，不管怎样函 理由：K&R。 也请注意这种大括号的放置方式也能使空（或者差不多空的）行的数量最小化，同时不失可 -读性。因此，由于你的屏幕上的新行是不可再生资源（想想25行的终端屏幕），你将会有更 +读性。因此，由于你的屏幕上的新行是不可再生资源（想想 25 行的终端屏幕），你将会有更 多的空行来放置注释。 当只有一个单独的语句的时候，不用加不必要的大括号。 -if (condition) - action(); + if (condition) + action(); + +和 + + if (condition) + do_this(); + else + do_that(); -这点不适用于本身为某个条件语句的一个分支的单独语句。这时需要在两个分支里都使用大 -括号。 +这并不适用于只有一个条件分支是单语句的情况；这时所有分支都要使用大括号： -if (condition) { - do_this(); - do_that(); -} else { - otherwise(); -} + if (condition) { + do_this(); + do_that(); + } else { + otherwise(); + } 3.1：空格 -Linux内核的空格使用方式（主要）取决于它是用于函数还是关键字。（大多数）关键字后 -要加一个空格。值得注意的例外是sizeof、typeof、alignof和__attribute__，这些关键字 -某些程度上看起来更像函数（它们在Linux里也常常伴随小括号而使用，尽管在C语言里这样 -的小括号不是必需的，就像“struct fileinfo info”声明过后的“sizeof info”）。 +Linux 内核的空格使用方式（主要）取决于它是用于函数还是关键字。（大多数）关键字后 +要加一个空格。值得注意的例外是 sizeof、typeof、alignof 和 __attribute__，这些 +关键字某些程度上看起来更像函数（它们在 Linux 里也常常伴随小括号而使用，尽管在 C 里 +这样的小括号不是必需的，就像 “struct fileinfo info” 声明过后的 “sizeof info”）。 所以在这些关键字之后放一个空格： + if, switch, case, for, do, while -但是不要在sizeof、typeof、alignof或者__attribute__这些关键字之后放空格。例如， + +但是不要在 sizeof、typeof、alignof 或者 __attribute__ 这些关键字之后放空格。例如， + s = sizeof(struct file); 不要在小括号里的表达式两侧加空格。这是一个反例： s = sizeof( struct file ); -当声明指针类型或者返回指针类型的函数时，“*”的首选使用方式是使之靠近变量名或者函 +当声明指针类型或者返回指针类型的函数时，“*” 的首选使用方式是使之靠近变量名或者函 数名，而不是靠近类型名。例子： char *linux_banner; @@ -204,15 +202,18 @@ Linux内核的空格使用方式（主要）取决于它是用于函数还是关 = + - < > * / % | & ^ <= >= == != ? : 但是一元操作符后不要加空格： + & * + - ~ ! sizeof typeof alignof __attribute__ defined 后缀自加和自减一元操作符前不加空格： + ++ -- 前缀自加和自减一元操作符后不加空格： + ++ -- -“.”和“->”结构体成员操作符前后不加空格。 +‘.’ 和 “->” 结构体成员操作符前后不加空格。 不要在行尾留空白。有些可以自动缩进的编辑器会在新行的行首加入适量的空白，然后你 就可以直接在那一行输入代码。不过假如你最后没有在那一行输入代码，有些编辑器就不 @@ -225,23 +226,23 @@ Linux内核的空格使用方式（主要）取决于它是用于函数还是关 第四章：命名 -C是一个简朴的语言，你的命名也应该这样。和Modula-2和Pascal程序员不同，C程序员不使 -用类似ThisVariableIsATemporaryCounter这样华丽的名字。C程序员会称那个变量为“tmp” -，这样写起来会更容易，而且至少不会令其难于理解。 +C是一个简朴的语言，你的命名也应该这样。和 Modula-2 和 Pascal 程序员不同，C 程序员 +不使用类似 ThisVariableIsATemporaryCounter 这样华丽的名字。C 程序员会称那个变量 +为 “tmp”，这样写起来会更容易，而且至少不会令其难于理解。 不过，虽然混用大小写的名字是不提倡使用的，但是全局变量还是需要一个具描述性的名字 -。称一个全局函数为“foo”是一个难以饶恕的错误。 +。称一个全局函数为 “foo” 是一个难以饶恕的错误。 全局变量（只有当你真正需要它们的时候再用它）需要有一个具描述性的名字，就像全局函 -数。如果你有一个可以计算活动用户数量的函数，你应该叫它“count_active_users()”或者 -类似的名字，你不应该叫它“cntuser()”。 +数。如果你有一个可以计算活动用户数量的函数，你应该叫它 “count_active_users()” +或者类似的名字，你不应该叫它 “cntuser()”。 在函数名中包含函数类型（所谓的匈牙利命名法）是脑子出了问题——编译器知道那些类型而 且能够检查那些类型，这样做只能把程序员弄糊涂了。难怪微软总是制造出有问题的程序。 本地变量名应该简短，而且能够表达相关的含义。如果你有一些随机的整数型的循环计数器 -，它应该被称为“i”。叫它“loop_counter”并无益处，如果它没有被误解的可能的话。类似 -的，“tmp”可以用来称呼任意类型的临时变量。 +，它应该被称为 “i”。叫它 “loop_counter” 并无益处，如果它没有被误解的可能的话。 +类似的，“tmp” 可以用来称呼任意类型的临时变量。 如果你怕混淆了你的本地变量名，你就遇到另一个问题了，叫做函数增长荷尔蒙失衡综合症 。请看第六章（函数）。 @@ -249,9 +250,9 @@ C是一个简朴的语言，你的命名也应该这样。和Modula-2和Pascal 第五章：Typedef -不要使用类似“vps_t”之类的东西。 +不要使用类似 “vps_t” 之类的东西。 -对结构体和指针使用typedef是一个错误。当你在代码里看到： +对结构体和指针使用 typedef 是一个错误。当你在代码里看到： vps_t a; @@ -261,91 +262,91 @@ C是一个简朴的语言，你的命名也应该这样。和Modula-2和Pascal struct virtual_container *a; -你就知道“a”是什么了。 +你就知道 “a” 是什么了。 -很多人认为typedef“能提高可读性”。实际不是这样的。它们只在下列情况下有用： +很多人认为 typedef “能提高可读性”。实际不是这样的。它们只在下列情况下有用： - (a) 完全不透明的对象（这种情况下要主动使用typedef来隐藏这个对象实际上是什么）。 + (a) 完全不透明的对象（这种情况下要主动使用 typedef 来隐藏这个对象实际上是什么）。 - 例如：“pte_t”等不透明对象，你只能用合适的访问函数来访问它们。 + 例如：“pte_t” 等不透明对象，你只能用合适的访问函数来访问它们。 - 注意！不透明性和“访问函数”本身是不好的。我们使用pte_t等类型的原因在于真的是 + 注意！不透明性和“访问函数”本身是不好的。我们使用 pte_t 等类型的原因在于真的是 完全没有任何共用的可访问信息。 - (b) 清楚的整数类型，如此，这层抽象就可以帮助消除到底是“int”还是“long”的混淆。 + (b) 清楚的整数类型，如此，这层抽象就可以帮助消除到底是 “int” 还是 “long” 的混淆。 - u8/u16/u32是完全没有问题的typedef，不过它们更符合类别(d)而不是这里。 + u8/u16/u32 是完全没有问题的 typedef，不过它们更符合类别 (d) 而不是这里。 - 再次注意！要这样做，必须事出有因。如果某个变量是“unsigned long“，那么没有必要 + 再次注意！要这样做，必须事出有因。如果某个变量是 “unsigned long“，那么没有必要 typedef unsigned long myflags_t; - 不过如果有一个明确的原因，比如它在某种情况下可能会是一个“unsigned int”而在 - 其他情况下可能为“unsigned long”，那么就不要犹豫，请务必使用typedef。 + 不过如果有一个明确的原因，比如它在某种情况下可能会是一个 “unsigned int” 而在 + 其他情况下可能为 “unsigned long”，那么就不要犹豫，请务必使用 typedef。 (c) 当你使用sparse按字面的创建一个新类型来做类型检查的时候。 (d) 和标准C99类型相同的类型，在某些例外的情况下。 - 虽然让眼睛和脑筋来适应新的标准类型比如“uint32_t”不需要花很多时间，可是有些 + 虽然让眼睛和脑筋来适应新的标准类型比如 “uint32_t” 不需要花很多时间，可是有些 人仍然拒绝使用它们。 - 因此，Linux特有的等同于标准类型的“u8/u16/u32/u64”类型和它们的有符号类型是被 + 因此，Linux 特有的等同于标准类型的 “u8/u16/u32/u64” 类型和它们的有符号类型是被 允许的——尽管在你自己的新代码中，它们不是强制要求要使用的。 当编辑已经使用了某个类型集的已有代码时，你应该遵循那些代码中已经做出的选择。 (e) 可以在用户空间安全使用的类型。 - 在某些用户空间可见的结构体里，我们不能要求C99类型而且不能用上面提到的“u32” - 类型。因此，我们在与用户空间共享的所有结构体中使用__u32和类似的类型。 + 在某些用户空间可见的结构体里，我们不能要求C99类型而且不能用上面提到的 “u32” + 类型。因此，我们在与用户空间共享的所有结构体中使用 __u32 和类似的类型。 -可能还有其他的情况，不过基本的规则是永远不要使用typedef，除非你可以明确的应用上 +可能还有其他的情况，不过基本的规则是永远不要使用 typedef，除非你可以明确的应用上 述某个规则中的一个。 总的来说，如果一个指针或者一个结构体里的元素可以合理的被直接访问到，那么它们就不 -应该是一个typedef。 +应该是一个 typedef。 第六章：函数 函数应该简短而漂亮，并且只完成一件事情。函数应该可以一屏或者两屏显示完（我们都知 -道ISO/ANSI屏幕大小是80x24），只做一件事情，而且把它做好。 +道 ISO/ANSI 屏幕大小是 80x24），只做一件事情，而且把它做好。 一个函数的最大长度是和该函数的复杂度和缩进级数成反比的。所以，如果你有一个理论上 -很简单的只有一个很长（但是简单）的case语句的函数，而且你需要在每个case里做很多很 -小的事情，这样的函数尽管很长，但也是可以的。 +很简单的只有一个很长（但是简单）的 case 语句的函数，而且你需要在每个 case 里做 +很多很小的事情，这样的函数尽管很长，但也是可以的。 不过，如果你有一个复杂的函数，而且你怀疑一个天分不是很高的高中一年级学生可能甚至 搞不清楚这个函数的目的，你应该严格的遵守前面提到的长度限制。使用辅助函数，并为之 取个具描述性的名字（如果你觉得它们的性能很重要的话，可以让编译器内联它们，这样的 效果往往会比你写一个复杂函数的效果要好。） -函数的另外一个衡量标准是本地变量的数量。此数量不应超过5－10个，否则你的函数就有 +函数的另外一个衡量标准是本地变量的数量。此数量不应超过 5－10 个，否则你的函数就有 问题了。重新考虑一下你的函数，把它分拆成更小的函数。人的大脑一般可以轻松的同时跟 -踪7个不同的事物，如果再增多的话，就会糊涂了。即便你聪颖过人，你也可能会记不清你2 -个星期前做过的事情。 +踪 7 个不同的事物，如果再增多的话，就会糊涂了。即便你聪颖过人，你也可能会记不清你 +2 个星期前做过的事情。 -在源文件里，使用空行隔开不同的函数。如果该函数需要被导出，它的EXPORT*宏应该紧贴 +在源文件里，使用空行隔开不同的函数。如果该函数需要被导出，它的 EXPORT* 宏应该紧贴 在它的结束大括号之下。比如： -int system_is_up(void) -{ - return system_state == SYSTEM_RUNNING; -} -EXPORT_SYMBOL(system_is_up); + int system_is_up(void) + { + return system_state == SYSTEM_RUNNING; + } + EXPORT_SYMBOL(system_is_up); -在函数原型中，包含函数名和它们的数据类型。虽然C语言里没有这样的要求，在Linux里这 +在函数原型中，包含函数名和它们的数据类型。虽然C语言里没有这样的要求，在 Linux 里这 是提倡的做法，因为这样可以很简单的给读者提供更多的有价值的信息。 第七章：集中的函数退出途径 -虽然被某些人声称已经过时，但是goto语句的等价物还是经常被编译器所使用，具体形式是 +虽然被某些人声称已经过时，但是 goto 语句的等价物还是经常被编译器所使用，具体形式是 无条件跳转指令。 -当一个函数从多个位置退出并且需要做一些通用的清理工作的时候，goto的好处就显现出来 -了。 +当一个函数从多个位置退出，并且需要做一些类似清理的常见操作时，goto 语句就很方便了。 +如果并不需要清理操作，那么直接 return 即可。 理由是： @@ -354,26 +355,37 @@ EXPORT_SYMBOL(system_is_up); - 可以避免由于修改时忘记更新某个单独的退出点而导致的错误 - 减轻了编译器的工作，无需删除冗余代码;) -int fun(int a) -{ - int result = 0; - char *buffer = kmalloc(SIZE); - - if (buffer == NULL) - return -ENOMEM; - - if (condition1) { - while (loop1) { - ... + int fun(int a) + { + int result = 0; + char *buffer; + + buffer = kmalloc(SIZE, GFP_KERNEL); + if (!buffer) + return -ENOMEM; + + if (condition1) { + while (loop1) { + ... + } + result = 1; + goto out_buffer; } - result = 1; - goto out; + ... + out_buffer: + kfree(buffer); + return result; } - ... -out: - kfree(buffer); - return result; -} + +一个需要注意的常见错误是“一个 err 错误”，就像这样： + + err: + kfree(foo->bar); + kfree(foo); + return ret; + +这段代码的错误是，在某些退出路径上 “foo” 是 NULL。通常情况下，通过把它分离成两个 +错误标签 “err_bar:” 和 “err_foo:” 来修复这个错误。 第八章：注释 @@ -386,10 +398,10 @@ out: 加太多。你应该做的，是把注释放在函数的头部，告诉人们它做了什么，也可以加上它做这 些事情的原因。 -当注释内核API函数时，请使用kernel-doc格式。请看 -Documentation/kernel-doc-nano-HOWTO.txt和scripts/kernel-doc以获得详细信息。 +当注释内核API函数时，请使用 kernel-doc 格式。请看 +Documentation/kernel-doc-nano-HOWTO.txt和scripts/kernel-doc 以获得详细信息。 -Linux的注释风格是C89“/* ... */”风格。不要使用C99风格“// ...”注释。 +Linux的注释风格是 C89 “/* ... */” 风格。不要使用 C99 风格 “// ...” 注释。 长（多行）的首选注释风格是： @@ -402,6 +414,15 @@ Linux的注释风格是C89“/* ... */”风格。不要使用C99风格“// ... * with beginning and ending almost-blank lines. */ +对于在 net/ 和 drivers/net/ 的文件，首选的长（多行）注释风格有些不同。 + + /* The preferred comment style for files in net/ and drivers/net + * looks like this. + * + * It is nearly the same as the generally preferred comment style, + * but there is no initial almost-blank line. + */ + 注释数据也是很重要的，不管是基本类型还是衍生类型。为了方便实现这一点，每一行应只 声明一个数据（不要使用逗号来一次声明多个数据）。这样你就有空间来为每个数据写一段 小注释来解释它们的用途了。 @@ -409,49 +430,63 @@ Linux的注释风格是C89“/* ... */”风格。不要使用C99风格“// ... 第九章：你已经把事情弄糟了 -这没什么，我们都是这样。可能你的使用了很长时间Unix的朋友已经告诉你“GNU emacs”能 -自动帮你格式化C源代码，而且你也注意到了，确实是这样，不过它所使用的默认值和我们 -想要的相去甚远（实际上，甚至比随机打的还要差——无数个猴子在GNU emacs里打字永远不 -会创造出一个好程序）（译注：请参考Infinite Monkey Theorem） - -所以你要么放弃GNU emacs，要么改变它让它使用更合理的设定。要采用后一个方案，你可 -以把下面这段粘贴到你的.emacs文件里。 - -(defun linux-c-mode () - "C mode with adjusted defaults for use with the Linux kernel." - (interactive) - (c-mode) - (c-set-style "K&R") - (setq tab-width 8) - (setq indent-tabs-mode t) - (setq c-basic-offset 8)) - -这样就定义了M-x linux-c-mode命令。当你hack一个模块的时候，如果你把字符串 --*- linux-c -*-放在头两行的某个位置，这个模式将会被自动调用。如果你希望在你修改 -/usr/src/linux里的文件时魔术般自动打开linux-c-mode的话，你也可能需要添加 - -(setq auto-mode-alist (cons '("/usr/src/linux.*/.*\\.[ch]$" . linux-c-mode) - auto-mode-alist)) - -到你的.emacs文件里。 - -不过就算你尝试让emacs正确的格式化代码失败了，也并不意味着你失去了一切：还可以用“ -indent”。 - -不过，GNU indent也有和GNU emacs一样有问题的设定，所以你需要给它一些命令选项。不 -过，这还不算太糟糕，因为就算是GNU indent的作者也认同K&R的权威性（GNU的人并不是坏 -人，他们只是在这个问题上被严重的误导了），所以你只要给indent指定选项“-kr -i8” -（代表“K&R，8个字符缩进”），或者使用“scripts/Lindent”，这样就可以以最时髦的方式 +这没什么，我们都是这样。可能你的使用了很长时间 Unix 的朋友已经告诉你 “GNU emacs” 能 +自动帮你格式化 C 源代码，而且你也注意到了，确实是这样，不过它所使用的默认值和我们 +想要的相去甚远（实际上，甚至比随机打的还要差——无数个猴子在 GNU emacs 里打字永远不 +会创造出一个好程序）（译注：请参考 Infinite Monkey Theorem） + +所以你要么放弃 GNU emacs，要么改变它让它使用更合理的设定。要采用后一个方案，你可 +以把下面这段粘贴到你的 .emacs 文件里。 + +(defun c-lineup-arglist-tabs-only (ignored) + "Line up argument lists by tabs, not spaces" + (let* ((anchor (c-langelem-pos c-syntactic-element)) + (column (c-langelem-2nd-pos c-syntactic-element)) + (offset (- (1+ column) anchor)) + (steps (floor offset c-basic-offset))) + (* (max steps 1) + c-basic-offset))) + +(add-hook 'c-mode-common-hook + (lambda () + ;; Add kernel style + (c-add-style + "linux-tabs-only" + '("linux" (c-offsets-alist + (arglist-cont-nonempty + c-lineup-gcc-asm-reg + c-lineup-arglist-tabs-only)))))) + +(add-hook 'c-mode-hook + (lambda () + (let ((filename (buffer-file-name))) + ;; Enable kernel mode for the appropriate files + (when (and filename + (string-match (expand-file-name "~/src/linux-trees") + filename)) + (setq indent-tabs-mode t) + (setq show-trailing-whitespace t) + (c-set-style "linux-tabs-only"))))) + +这会让 emacs 在 ~/src/linux-trees 目录下的 C 源文件获得更好的内核代码风格。 + +不过就算你尝试让 emacs 正确的格式化代码失败了，也并不意味着你失去了一切：还可以用 +“indent”。 + +不过，GNU indent 也有和 GNU emacs 一样有问题的设定，所以你需要给它一些命令选项。不 +过，这还不算太糟糕，因为就算是 GNU indent 的作者也认同 K&R 的权威性（GNU 的人并不是 +坏人，他们只是在这个问题上被严重的误导了），所以你只要给 indent 指定选项 “-kr -i8” +（代表 “K&R，8 个字符缩进”），或者使用 “scripts/Lindent”，这样就可以以最时髦的方式 缩进源代码。 -“indent”有很多选项，特别是重新格式化注释的时候，你可能需要看一下它的手册页。不过 -记住：“indent”不能修正坏的编程习惯。 +“indent” 有很多选项，特别是重新格式化注释的时候，你可能需要看一下它的手册页。不过 +记住：“indent” 不能修正坏的编程习惯。 - 第十章：Kconfig配置文件 + 第十章：Kconfig 配置文件 -对于遍布源码树的所有Kconfig*配置文件来说，它们缩进方式与C代码相比有所不同。紧挨 -在“config”定义下面的行缩进一个制表符，帮助信息则再多缩进2个空格。比如： +对于遍布源码树的所有 Kconfig* 配置文件来说，它们缩进方式与 C 代码相比有所不同。紧挨 +在 “config” 定义下面的行缩进一个制表符，帮助信息则再多缩进 2 个空格。比如： config AUDIT bool "Auditing support" @@ -470,7 +505,7 @@ config ADFS_FS_RW depends on ADFS_FS ... -要查看配置文件的完整文档，请看Documentation/kbuild/kconfig-language.txt。 +要查看配置文件的完整文档，请看 Documentation/kbuild/kconfig-language.txt。 第十一章：数据结构 @@ -489,11 +524,11 @@ config ADFS_FS_RW 很多数据结构实际上有2级引用计数，它们通常有不同“类”的用户。子类计数器统计子类用 户的数量，每当子类计数器减至零时，全局计数器减一。 -这种“多级引用计数”的例子可以在内存管理（“struct mm_struct”：mm_users和mm_count） +这种“多级引用计数”的例子可以在内存管理（“struct mm_struct”：mm_users 和 mm_count） 和文件系统（“struct super_block”：s_count和s_active）中找到。 记住：如果另一个执行线索可以找到你的数据结构，但是这个数据结构没有引用计数器，这 -里几乎肯定是一个bug。 +里几乎肯定是一个 bug。 第十二章：宏，枚举和RTL @@ -508,102 +543,128 @@ config ADFS_FS_RW 一般的，如果能写成内联函数就不要写成像函数的宏。 -含有多个语句的宏应该被包含在一个do-while代码块里： +含有多个语句的宏应该被包含在一个 do-while 代码块里： -#define macrofun(a, b, c) \ - do { \ - if (a == 5) \ - do_this(b, c); \ - } while (0) + #define macrofun(a, b, c) \ + do { \ + if (a == 5) \ + do_this(b, c); \ + } while (0) 使用宏的时候应避免的事情： 1) 影响控制流程的宏： -#define FOO(x) \ - do { \ - if (blah(x) < 0) \ - return -EBUGGERED; \ - } while(0) + #define FOO(x) \ + do { \ + if (blah(x) < 0) \ + return -EBUGGERED; \ + } while (0) 非常不好。它看起来像一个函数，不过却能导致“调用”它的函数退出；不要打乱读者大脑里 的语法分析器。 2) 依赖于一个固定名字的本地变量的宏： -#define FOO(val) bar(index, val) + #define FOO(val) bar(index, val) 可能看起来像是个不错的东西，不过它非常容易把读代码的人搞糊涂，而且容易导致看起来 不相关的改动带来错误。 -3) 作为左值的带参数的宏： FOO(x) = y；如果有人把FOO变成一个内联函数的话，这种用 +3) 作为左值的带参数的宏： FOO(x) = y；如果有人把 FOO 变成一个内联函数的话，这种用 法就会出错了。 4) 忘记了优先级：使用表达式定义常量的宏必须将表达式置于一对小括号之内。带参数的 宏也要注意此类问题。 -#define CONSTANT 0x4000 -#define CONSTEXP (CONSTANT | 3) + #define CONSTANT 0x4000 + #define CONSTEXP (CONSTANT | 3) + +5) 在宏里定义类似函数的本地变量时命名冲突： -cpp手册对宏的讲解很详细。Gcc internals手册也详细讲解了RTL（译注：register + #define FOO(x) \ + ({ \ + typeof(x) ret; \ + ret = calc_ret(x); \ + (ret); \ + }) + +ret 是本地变量的通用名字 - __foo_ret 更不容易与一个已存在的变量冲突。 + +cpp 手册对宏的讲解很详细。gcc internals 手册也详细讲解了 RTL（译注：register transfer language），内核里的汇编语言经常用到它。 第十三章：打印内核消息 内核开发者应该是受过良好教育的。请一定注意内核信息的拼写，以给人以好的印象。不要 -用不规范的单词比如“dont”，而要用“do not”或者“don't”。保证这些信息简单、明了、无 -歧义。 +用不规范的单词比如 “dont”，而要用 “do not”或者 “don't”。保证这些信息简单、明了、 +无歧义。 内核信息不必以句号（译注：英文句号，即点）结束。 -在小括号里打印数字(%d)没有任何价值，应该避免这样做。 +在小括号里打印数字 (%d) 没有任何价值，应该避免这样做。 -<linux/device.h>里有一些驱动模型诊断宏，你应该使用它们，以确保信息对应于正确的 -设备和驱动，并且被标记了正确的消息级别。这些宏有：dev_err(), dev_warn(), -dev_info()等等。对于那些不和某个特定设备相关连的信息，<linux/kernel.h>定义了 -pr_debug()和pr_info()。 +<linux/device.h> 里有一些驱动模型诊断宏，你应该使用它们，以确保信息对应于正确的 +设备和驱动，并且被标记了正确的消息级别。这些宏有：dev_err()，dev_warn()， +dev_info() 等等。对于那些不和某个特定设备相关连的信息，<linux/printk.h> 定义了 +pr_notice()，pr_info()，pr_warn()，pr_err() 和其他。 -写出好的调试信息可以是一个很大的挑战；当你写出来之后，这些信息在远程除错的时候 -就会成为极大的帮助。当DEBUG符号没有被定义的时候，这些信息不应该被编译进内核里 -（也就是说，默认地，它们不应该被包含在内）。如果你使用dev_dbg()或者pr_debug()， -就能自动达到这个效果。很多子系统拥有Kconfig选项来启用-DDEBUG。还有一个相关的惯例 -是使用VERBOSE_DEBUG来添加dev_vdbg()消息到那些已经由DEBUG启用的消息之上。 +写出好的调试信息可以是一个很大的挑战；一旦你写出后，这些信息在远程除错时能提供极大 +的帮助。然而打印调试信息的处理方式同打印非调试信息不同。其他 pr_XXX() 函数能无条件地 +打印，pr_debug() 却不；默认情况下它不会被编译，除非定义了 DEBUG 或设定了 +CONFIG_DYNAMIC_DEBUG。实际这同样是为了 dev_dbg()，一个相关约定是在一个已经开启了 +DEBUG 时，使用 VERBOSE_DEBUG 来添加 dev_vdbg()。 + +许多子系统拥有 Kconfig 调试选项来开启 -DDEBUG 在对应的 Makefile 里面；在其他 +情况下，特殊文件使用 #define DEBUG。当一条调试信息需要被无条件打印时，例如，如果 +已经包含一个调试相关的 #ifdef 条件，printk(KERN_DEBUG ...) 就可被使用。 第十四章：分配内存 -内核提供了下面的一般用途的内存分配函数：kmalloc()，kzalloc()，kcalloc()和 -vmalloc()。请参考API文档以获取有关它们的详细信息。 +内核提供了下面的一般用途的内存分配函数： +kmalloc()，kzalloc()，kmalloc_array()，kcalloc()，vmalloc() 和 vzalloc()。 +请参考 API 文档以获取有关它们的详细信息。 传递结构体大小的首选形式是这样的： p = kmalloc(sizeof(*p), ...); -另外一种传递方式中，sizeof的操作数是结构体的名字，这样会降低可读性，并且可能会引 -入bug。有可能指针变量类型被改变时，而对应的传递给内存分配函数的sizeof的结果不变。 +另外一种传递方式中，sizeof 的操作数是结构体的名字，这样会降低可读性，并且可能会引 +入 bug。有可能指针变量类型被改变时，而对应的传递给内存分配函数的 sizeof 的结果不变。 -强制转换一个void指针返回值是多余的。C语言本身保证了从void指针到其他任何指针类型 +强制转换一个 void 指针返回值是多余的。C 语言本身保证了从 void 指针到其他任何指针类型 的转换是没有问题的。 +分配一个数组的首选形式是这样的： + + p = kmalloc_array(n, sizeof(...), ...); + +分配一个零长数组的首选形式是这样的： + + p = kcalloc(n, sizeof(...), ...); + +两种形式检查分配大小 n * sizeof(...) 的溢出，如果溢出返回 NULL。 + 第十五章：内联弊病 -有一个常见的误解是内联函数是gcc提供的可以让代码运行更快的一个选项。虽然使用内联 +有一个常见的误解是内联函数是 gcc 提供的可以让代码运行更快的一个选项。虽然使用内联 函数有时候是恰当的（比如作为一种替代宏的方式，请看第十二章），不过很多情况下不是 -这样。inline关键字的过度使用会使内核变大，从而使整个系统运行速度变慢。因为大内核 +这样。inline 关键字的过度使用会使内核变大，从而使整个系统运行速度变慢。因为大内核 会占用更多的指令高速缓存（译注：一级缓存通常是指令缓存和数据缓存分开的）而且会导 -致pagecache的可用内存减少。想象一下，一次pagecache未命中就会导致一次磁盘寻址，将 -耗时5毫秒。5毫秒的时间内CPU能执行很多很多指令。 +致 pagecache 的可用内存减少。想象一下，一次pagecache未命中就会导致一次磁盘寻址， +将耗时 5 毫秒。5 毫秒的时间内 CPU 能执行很多很多指令。 -一个基本的原则是如果一个函数有3行以上，就不要把它变成内联函数。这个原则的一个例 +一个基本的原则是如果一个函数有 3 行以上，就不要把它变成内联函数。这个原则的一个例 外是，如果你知道某个参数是一个编译时常量，而且因为这个常量你确定编译器在编译时能 -优化掉你的函数的大部分代码，那仍然可以给它加上inline关键字。kmalloc()内联函数就 +优化掉你的函数的大部分代码，那仍然可以给它加上 inline 关键字。kmalloc() 内联函数就 是一个很好的例子。 -人们经常主张给static的而且只用了一次的函数加上inline，如此不会有任何损失，因为没 -有什么好权衡的。虽然从技术上说这是正确的，但是实际上这种情况下即使不加inline gcc -也可以自动使其内联。而且其他用户可能会要求移除inline，由此而来的争论会抵消inline +人们经常主张给 static 的而且只用了一次的函数加上 inline，如此不会有任何损失，因为没 +有什么好权衡的。虽然从技术上说这是正确的，但是实际上这种情况下即使不加 inline gcc +也可以自动使其内联。而且其他用户可能会要求移除 inline，由此而来的争论会抵消 inline 自身的潜在价值，得不偿失。 @@ -613,37 +674,37 @@ vmalloc()。请参考API文档以获取有关它们的详细信息。 的一个值可以表示为一个错误代码整数（-Exxx＝失败，0＝成功）或者一个“成功”布尔值（ 0＝失败，非0＝成功）。 -混合使用这两种表达方式是难于发现的bug的来源。如果C语言本身严格区分整形和布尔型变 -量，那么编译器就能够帮我们发现这些错误……不过C语言不区分。为了避免产生这种bug，请 +混合使用这两种表达方式是难于发现的 bug 的来源。如果 C 语言本身严格区分整形和布尔型变 +量，那么编译器就能够帮我们发现这些错误……不过 C 语言不区分。为了避免产生这种 bug，请 遵循下面的惯例： 如果函数的名字是一个动作或者强制性的命令，那么这个函数应该返回错误代码整 数。如果是一个判断，那么函数应该返回一个“成功”布尔值。 -比如，“add work”是一个命令，所以add_work()函数在成功时返回0，在失败时返回-EBUSY。 -类似的，因为“PCI device present”是一个判断，所以pci_dev_present()函数在成功找到 -一个匹配的设备时应该返回1，如果找不到时应该返回0。 +比如，“add work” 是一个命令，所以 add_work() 函数在成功时返回 0，在失败时返回 -EBUSY。 +类似的，因为 “PCI device present” 是一个判断，所以 pci_dev_present() 函数在成功找到 +一个匹配的设备时应该返回 1，如果找不到时应该返回 0。 所有导出（译注：EXPORT）的函数都必须遵守这个惯例，所有的公共函数也都应该如此。私 有（static）函数不需要如此，但是我们也推荐这样做。 返回值是实际计算结果而不是计算是否成功的标志的函数不受此惯例的限制。一般的，他们 通过返回一些正常值范围之外的结果来表示出错。典型的例子是返回指针的函数，他们使用 -NULL或者ERR_PTR机制来报告错误。 +NULL 或者 ERR_PTR 机制来报告错误。 第十七章：不要重新发明内核宏 -头文件include/linux/kernel.h包含了一些宏，你应该使用它们，而不要自己写一些它们的 +头文件 include/linux/kernel.h 包含了一些宏，你应该使用它们，而不要自己写一些它们的 变种。比如，如果你需要计算一个数组的长度，使用这个宏 - #define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0])) + #define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0])) 类似的，如果你要计算某结构体成员的大小，使用 - #define FIELD_SIZEOF(t, f) (sizeof(((t*)0)->f)) + #define FIELD_SIZEOF(t, f) (sizeof(((t*)0)->f)) -还有可以做严格的类型检查的min()和max()宏，如果你需要可以使用它们。你可以自己看看 +还有可以做严格的类型检查的 min() 和 max() 宏，如果你需要可以使用它们。你可以自己看看 那个头文件里还定义了什么你可以拿来用的东西，如果有定义的话，你就不应在你的代码里 自己重新定义。 @@ -653,42 +714,100 @@ NULL或者ERR_PTR机制来报告错误。 有一些编辑器可以解释嵌入在源文件里的由一些特殊标记标明的配置信息。比如，emacs 能够解释被标记成这样的行： --*- mode: c -*- + -*- mode: c -*- 或者这样的： -/* -Local Variables: -compile-command: "gcc -DMAGIC_DEBUG_FLAG foo.c" -End: -*/ + /* + Local Variables: + compile-command: "gcc -DMAGIC_DEBUG_FLAG foo.c" + End: + */ -Vim能够解释这样的标记： +Vim 能够解释这样的标记： -/* vim:set sw=8 noet */ + /* vim:set sw=8 noet */ 不要在源代码中包含任何这样的内容。每个人都有他自己的编辑器配置，你的源文件不应 该覆盖别人的配置。这包括有关缩进和模式配置的标记。人们可以使用他们自己定制的模 式，或者使用其他可以产生正确的缩进的巧妙方法。 + 第十九章：内联汇编 + +在特定架构的代码中，你也许需要内联汇编来使用 CPU 接口和平台相关功能。在需要 +这么做时，不要犹豫。然而，当 C 可以完成工作时，不要无端地使用内联汇编。如果 +可能，你可以并且应该用 C 和硬件交互。 + +考虑去写通用一点的内联汇编作为简明的辅助函数，而不是重复写下它们的细节。记住 +内联汇编可以使用 C 参数。 + +大而特殊的汇编函数应该放在 .S 文件中，对应 C 的原型定义在 C 头文件中。汇编 +函数的 C 原型应该使用 “asmlinkage”。 + +你可能需要将你的汇编语句标记为 volatile，来阻止 GCC 在没发现任何副作用后就 +移除了它。你不必总是这样做，虽然，这样可以限制不必要的优化。 + +在写一个包含多条指令的单个内联汇编语句时，把每条指令用引号字符串分离，并写在 +单独一行，在每个字符串结尾，除了 \n\t 结尾之外，在汇编输出中适当地缩进下 +一条指令： + + asm ("magic %reg1, #42\n\t" + "more_magic %reg2, %reg3" + : /* outputs */ : /* inputs */ : /* clobbers */); + + + 第二十章：条件编译 + +只要可能，就不要在 .c 文件里面使用预处理条件；这样做让代码更难阅读并且逻辑难以 +跟踪。替代方案是，在头文件定义函数在这些 .c 文件中使用这类的条件表达式，提供空 +操作的桩版本（译注：桩程序，是指用来替换一部分功能的程序段）在 #else 情况下， +再从 .c 文件中无条件地调用这些函数。编译器会避免生成任何桩调用的代码，产生一致 +的结果，但逻辑将更加清晰。 + +宁可编译整个函数，而不是部分函数或部分表达式。而不是在一个表达式添加 ifdef， +解析部分或全部表达式到一个单独的辅助函数，并应用条件到该函数内。 + +如果你有一个在特定配置中可能是未使用的函数或变量，编译器将警告它定义了但未使用， +标记这个定义为 __maybe_unused 而不是将它包含在一个预处理条件中。（然而，如果 +一个函数或变量总是未使用的，就直接删除它。） + +在代码中，可能的情况下，使用 IS_ENABLED 宏来转化某个 Kconfig 标记为 C 的布尔 +表达式，并在正常的 C 条件中使用它： + + if (IS_ENABLED(CONFIG_SOMETHING)) { + ... + } + +编译器会无条件地做常数合并，就像使用 #ifdef 那样，包含或排除代码块，所以这不会 +带来任何运行时开销。然而，这种方法依旧允许 C 编译器查看块内的代码，并检查它的正确 +性（语法，类型，符号引用，等等）。因此，如果条件不满足，代码块内的引用符号将不存在， +你必须继续使用 #ifdef。 + +在任何有意义的 #if 或 #ifdef 块的末尾（超过几行），在 #endif 同一行的后面写下 +注释，指出该条件表达式被使用。例如： + + #ifdef CONFIG_SOMETHING + ... + #endif /* CONFIG_SOMETHING */ + 附录 I：参考 -The C Programming Language, 第二版, 作者Brian W. Kernighan和Denni -M. Ritchie. Prentice Hall, Inc., 1988. ISBN 0-13-110362-8 (软皮), -0-13-110370-9 (硬皮). URL: http://cm.bell-labs.com/cm/cs/cbook/ +The C Programming Language, 第二版 +作者：Brian W. Kernighan 和 Denni M. Ritchie. +Prentice Hall, Inc., 1988. +ISBN 0-13-110362-8 (软皮), 0-13-110370-9 (硬皮). -The Practice of Programming 作者Brian W. Kernighan和Rob Pike. Addison-Wesley, -Inc., 1999. ISBN 0-201-61586-X. URL: http://cm.bell-labs.com/cm/cs/tpop/ +The Practice of Programming +作者：Brian W. Kernighan 和 Rob Pike. +Addison-Wesley, Inc., 1999. +ISBN 0-201-61586-X. -cpp，gcc，gcc internals和indent的GNU手册——和K&R及本文相符合的部分，全部可以在 -http://www.gnu.org/manual/找到 +GNU 手册 - 遵循 K&R 标准和此文本 - cpp, gcc, gcc internals and indent, +都可以从 http://www.gnu.org/manual/ 找到 WG14是C语言的国际标准化工作组，URL: http://www.open-std.org/JTC1/SC22/WG14/ -Kernel CodingStyle，作者greg@kroah.com发表于OLS 2002： +Kernel CodingStyle，作者 greg@kroah.com 发表于OLS 2002： http://www.kroah.com/linux/talks/ols_2002_kernel_codingstyle_talk/html/ - --- -最后更新于2007年7月13日。 |