[PATCH 2/2] PM / Runtime: use deferrable timer for autosuspend

From: Lucas Stach
Date: Tue Jan 12 2016 - 12:17:32 EST

The timeouts used in PM autosuspend are relatively coarse (the shortest
I could find in a quick search through the kernel is 50ms). As they are
already handled relaxed by saving the overhead of always rearming the
timer by opportunistically suspending a device a bit early, it should
not matter if the the timeout is missed slightly.

By using a deferrable timer the CPU will not be woken just to handle
the autosuspend timeout, but handling will be batched with other
wakeups in the system.

Signed-off-by: Lucas Stach <l.stach@xxxxxxxxxxxxxx>
drivers/base/power/runtime.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c
index e1a10a03df8e..975a282600ff 100644
--- a/drivers/base/power/runtime.c
+++ b/drivers/base/power/runtime.c
@@ -1383,7 +1383,7 @@ void pm_runtime_init(struct device *dev)
INIT_WORK(&dev->power.work, pm_runtime_work);

dev->power.timer_expires = 0;
- setup_timer(&dev->power.suspend_timer, pm_suspend_timer_fn,
+ setup_deferrable_timer(&dev->power.suspend_timer, pm_suspend_timer_fn,
(unsigned long)dev);