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PM / Sleep: Use wait queue to signal "no wakeup events in progress"

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The current wakeup source deactivation code doesn't do anything when
the counter of wakeup events in progress goes down to zero, which
requires pm_get_wakeup_count() to poll that counter periodically.
Although this reduces the average time it takes to deactivate a
wakeup source, it also may lead to a substantial amount of unnecessary
polling if there are extended periods of wakeup activity.  Thus it
seems reasonable to use a wait queue for signaling the "no wakeup
events in progress" condition and remove the polling.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: mark gross <markgross@thegnar.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Rafael J. Wysocki 2012-04-29 22:52:34 +02:00
parent 52d136cc2c
commit 60af106691
1 changed files with 13 additions and 3 deletions
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16
drivers/base/power/wakeup.c
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@ -17,8 +17,6 @@
#include "power.h"
#define TIMEOUT 100
/*
* If set, the suspend/hibernate code will abort transitions to a sleep state
* if wakeup events are registered during or immediately before the transition.
@ -52,6 +50,8 @@ static void pm_wakeup_timer_fn(unsigned long data);
static LIST_HEAD(wakeup_sources);
static DECLARE_WAIT_QUEUE_HEAD(wakeup_count_wait_queue);
/**
* wakeup_source_prepare - Prepare a new wakeup source for initialization.
* @ws: Wakeup source to prepare.
@ -442,6 +442,7 @@ EXPORT_SYMBOL_GPL(pm_stay_awake);
*/
static void wakeup_source_deactivate(struct wakeup_source *ws)
{
unsigned int cnt, inpr;
ktime_t duration;
ktime_t now;
@ -476,6 +477,10 @@ static void wakeup_source_deactivate(struct wakeup_source *ws)
* couter of wakeup events in progress simultaneously.
*/
atomic_add(MAX_IN_PROGRESS, &combined_event_count);
split_counters(&cnt, &inpr);
if (!inpr && waitqueue_active(&wakeup_count_wait_queue))
wake_up(&wakeup_count_wait_queue);
}
/**
@ -667,14 +672,19 @@ bool pm_wakeup_pending(void)
bool pm_get_wakeup_count(unsigned int *count)
{
unsigned int cnt, inpr;
DEFINE_WAIT(wait);
for (;;) {
prepare_to_wait(&wakeup_count_wait_queue, &wait,
TASK_INTERRUPTIBLE);
split_counters(&cnt, &inpr);
if (inpr == 0 || signal_pending(current))
break;
pm_wakeup_update_hit_counts();
schedule_timeout_interruptible(msecs_to_jiffies(TIMEOUT));
schedule();
}
finish_wait(&wakeup_count_wait_queue, &wait);
split_counters(&cnt, &inpr);
*count = cnt;