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Diffstat (limited to 'Documentation/driver-api/driver-model/driver.rst')
| -rw-r--r-- | Documentation/driver-api/driver-model/driver.rst | 32 |
1 files changed, 26 insertions, 6 deletions
diff --git a/Documentation/driver-api/driver-model/driver.rst b/Documentation/driver-api/driver-model/driver.rst index baa6a85c8287..06f818b1d622 100644 --- a/Documentation/driver-api/driver-model/driver.rst +++ b/Documentation/driver-api/driver-model/driver.rst @@ -4,7 +4,6 @@ Device Drivers See the kerneldoc for the struct device_driver. - Allocation ~~~~~~~~~~ @@ -167,9 +166,26 @@ the driver to that device. A driver's probe() may return a negative errno value to indicate that the driver did not bind to this device, in which case it should have -released all resources it allocated:: +released all resources it allocated. + +Optionally, probe() may return -EPROBE_DEFER if the driver depends on +resources that are not yet available (e.g., supplied by a driver that +hasn't initialized yet). The driver core will put the device onto the +deferred probe list and will try to call it again later. If a driver +must defer, it should return -EPROBE_DEFER as early as possible to +reduce the amount of time spent on setup work that will need to be +unwound and reexecuted at a later time. + +.. warning:: + -EPROBE_DEFER must not be returned if probe() has already created + child devices, even if those child devices are removed again + in a cleanup path. If -EPROBE_DEFER is returned after a child + device has been registered, it may result in an infinite loop of + .probe() calls to the same driver. + +:: - void (*sync_state)(struct device *dev); + void (*sync_state) (struct device *dev); sync_state is called only once for a device. It's called when all the consumer devices of the device have successfully probed. The list of consumers of the @@ -210,7 +226,7 @@ probed. While the typical use case for sync_state() is to have the kernel cleanly take over management of devices from the bootloader, the usage of sync_state() is not restricted to that. Use it whenever it makes sense to take an action after -all the consumers of a device have probed. +all the consumers of a device have probed:: int (*remove) (struct device *dev); @@ -224,11 +240,15 @@ not. It should free any resources allocated specifically for the device; i.e. anything in the device's driver_data field. If the device is still present, it should quiesce the device and place -it into a supported low-power state:: +it into a supported low-power state. + +:: int (*suspend) (struct device *dev, pm_message_t state); -suspend is called to put the device in a low power state:: +suspend is called to put the device in a low power state. + +:: int (*resume) (struct device *dev); |