From 580c398df70a959535406b791536cae98117929d Mon Sep 17 00:00:00 2001 From: Heiko Stuebner Date: Fri, 30 Dec 2011 23:16:19 +0100 Subject: [PATCH 1/4] 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. Signed-off-by: Heiko Stuebner --- drivers/video/fb_defio.c | 4 ++++ include/linux/fb.h | 1 + 2 files changed, 5 insertions(+), 0 deletions(-) diff --git a/drivers/video/fb_defio.c b/drivers/video/fb_defio.c index c27e153..070f26f 100644 --- a/drivers/video/fb_defio.c +++ b/drivers/video/fb_defio.c @@ -107,6 +107,10 @@ static int fb_deferred_io_mkwrite(struct vm_area_struct *vma, /* protect against the workqueue changing the page list */ mutex_lock(&fbdefio->lock); + /* first write in this cycle, notify the driver */ + if (fbdefio->first_io && list_empty(&fbdefio->pagelist)) + fbdefio->first_io(info); + /* * We want the page to remain locked from ->page_mkwrite until * the PTE is marked dirty to avoid page_mkclean() being called diff --git a/include/linux/fb.h b/include/linux/fb.h index d31cb68..c10e71e 100644 --- a/include/linux/fb.h +++ b/include/linux/fb.h @@ -607,6 +607,7 @@ struct fb_deferred_io { struct mutex lock; /* mutex that protects the page list */ struct list_head pagelist; /* list of touched pages */ /* callback */ + void (*first_io)(struct fb_info *info); void (*deferred_io)(struct fb_info *info, struct list_head *pagelist); }; #endif -- 1.7.5.4