egl: Add EGL_MESA_drm_image extension

Create EGLImages from DRM buffer handles.

1 files changed, 149 insertions, 0 deletions

diff --git a/docs/MESA_drm_image.spec b/docs/MESA_drm_image.spec
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+Name
+
+    MESA_drm_image
+
+Name Strings
+
+    EGL_MESA_drm_image
+
+Contact
+
+    Kristian Høgsberg <krh@bitplanet.net>
+
+Status
+
+    Proposal
+
+Version
+
+    Version 2, August 25, 2010
+
+Number
+
+    EGL Extension #not assigned
+
+Dependencies
+
+    Reguires EGL 1.4 or later.  This extension is written against the
+    wording of the EGL 1.4 specification.
+
+    EGL_KHR_base_image is required.
+
+Overview
+
+    This extension provides entry points for integrating EGLImage with the
+    Linux DRM mode setting and memory management drivers.  The extension
+    lets applications create EGLImages without a client API resource and
+    lets the application get the DRM buffer handles.
+
+IP Status
+
+    Open-source; freely implementable.
+
+New Procedures and Functions
+
+    EGLImageKHR eglCreateDRMImageMESA(EGLDisplay dpy,
+                                      const EGLint *attrib_list);
+
+    EGLBoolean eglExportDRMImageMESA(EGLDisplay dpy,
+                                     EGLImageKHR image,
+                                     EGLint *name,
+				     EGLint *handle,
+				     EGLint *stride);
+
+New Tokens
+
+    Accepted in the <attrib_list> parameter of eglCreateDRMImageMESA:
+
+        EGL_DRM_BUFFER_FORMAT_MESA		0x31D0
+        EGL_DRM_BUFFER_USE_MESA			0x31D1
+
+    Accepted as values for the EGL_IMAGE_FORMAT_MESA attribute:
+
+        EGL_DRM_BUFFER_FORMAT_ARGB32_MESA	0x31D2
+
+    Bits accepted in EGL_DRM_BUFFER_USE_MESA:
+
+        EGL_DRM_BUFFER_USE_SCANOUT_MESA		0x0001
+        EGL_DRM_BUFFER_USE_SHARE_MESA		0x0002
+
+    Accepted in the <target> parameter of eglCreateImageKHR:
+
+        EGL_DRM_BUFFER_MESA			0x31D3
+
+    Use when importing drm buffer:
+
+        EGL_DRM_BUFFER_STRIDE_MESA		0x31D4
+        EGL_DRM_BUFFER_FORMAT_MESA		0x31D0
+
+Additions to the EGL 1.4 Specification:
+
+    To create a DRM EGLImage, call
+
+        EGLImageKHR eglCreateDRMImageMESA(EGLDisplay dpy,
+                                          const EGLint *attrib_list);
+
+    In the attribute list, pass EGL_WIDTH, EGL_EIGHT and format and
+    use in the attrib list using EGL_DRM_BUFFER_FORMAT_MESA and
+    EGL_DRM_BUFFER_USE_MESA.  The only format specified by this
+    extension is EGL_DRM_BUFFER_FORMAT_ARGB32_MESA, where each pixel
+    is a CPU-endian, 32-bit quantity, with alpha in the upper 8 bits,
+    then red, then green, then blue.  The bit values accepted by
+    EGL_DRM_BUFFER_USE_MESA are EGL_DRM_BUFFER_USE_SCANOUT_MESA and
+    EGL_DRM_BUFFER_USE_SHARE_MESA.  EGL_DRM_BUFFER_USE_SCANOUT_MESA
+    requests that the created EGLImage should be usable as a scanout
+    buffer with the DRM kernel modesetting API.  The
+    EGL_DRM_BUFFER_USE_SHARE_MESA bit requests that the EGLImage can
+    be shared with other processes by passing the underlying DRM
+    buffer name.
+
+    To create a process local handle or a global DRM name for a
+    buffer, call
+
+        EGLBoolean eglExportDRMImageMESA(EGLDisplay dpy,
+                                         EGLImageKHR image,
+                                         EGLint *name,
+                                         EGLint *handle,
+                                         EGLint *stride);
+
+    If <name> is non-NULL, a global name is assigned to the image and
+    written to <name>, the handle (local to the DRM file descriptor,
+    for use with DRM kernel modesetting API) is written to <handle> if
+    non-NULL and the stride (in bytes) is written to <stride>, if
+    non-NULL.
+
+    Import a shared buffer by calling eglCreateImageKHR with
+    EGL_DRM_BUFFER_MESA as the target, using EGL_WIDTH, EGL_HEIGHT,
+    EGL_DRM_BUFFER_FORMAT_MESA, EGL_DRM_BUFFER_STRIDE_MESA
+    in the attrib list.
+
+Issues
+
+    1.  Why don't we use eglCreateImageKHR with a target that
+        indicates that we want to create an EGLImage from scratch?
+
+        RESOLVED: The eglCreateImageKHR entry point is reserved for
+        creating an EGLImage from an already existing client API
+        resource.  This is fine when we're creating the EGLImage from
+        an existing DRM buffer name, it doesn't seem right to overload
+        the function to also allocate the underlying resource.
+
+    2.  Why don't we use an eglQueryImageMESA type functions for
+        querying the DRM EGLImage attributes (name, handle, and stride)?
+
+        RESOLVED: The eglQueryImage function has been proposed often,
+        but it goes against the EGLImage design.  EGLImages are opaque
+        handles to a 2D array of pixels, which can be passed between
+        client APIs.  By referenceing an EGLImage in a client API, the
+        EGLImage target (a texture, a renderbuffer or such) can be
+        used to query the attributes of the EGLImage.  We don't have a
+        full client API for creating and querying DRM buffers, though,
+        so we use a new EGL extension entry point instead.
+
+Revision History
+
+    Version 1, June 3, 2010
+        Initial draft (Kristian Høgsberg)
+    Version 2, August 25, 2010
+        Flesh out the extension a bit, add final EGL tokens, capture
+        some of the original discussion in the issues section.