tree d914007ce3dd2c4ba94cad2af801b6ebd18552a5
parent 13f36e9ea0f1419039763e7ba947fccd7f4b5a41
author Heiko Stübner <heiko@sntech.de> 1335608350 +0200
committer Florian Tobias Schandinat <FlorianSchandinat@gmx.de> 1335728131 +0000

fb_defio: add first_io callback

With this optional callback the driver is notified when the first page
is entered into the pagelist and a new deferred_io call is scheduled.

A possible use-case for this is runtime-pm. In the first_io call
	pm_runtime_get()
could be called, which starts an asynchronous runtime_resume of the
device. In the deferred_io callback a call to
	pm_runtime_barrier()
makes the sure, the device is resumed by then and a
	pm_runtime_put()
may put the device back to sleep.

Also, some SoCs may use the runtime-pm system to determine if they
are able to enter deeper idle states. Therefore it is necessary to
keep the use-count from the first written page until the conclusion
of the screen update, to prevent the system from going to sleep before
completing the pending update.

Two users of defio were using kmalloc to allocate the structure.
These allocations are changed to kzalloc, to prevent uninitialised
.first_io members in those drivers.

Signed-off-by: Heiko Stübner <heiko@sntech.de>
Signed-off-by: Florian Tobias Schandinat <FlorianSchandinat@gmx.de>