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rtc: Keep system awake until all expired RTC timers are handled

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Current implementation of RTC interface allows for system suspend to
occur in the following cases:
(a) if a timer is set in the past and rtc_timer_do_work() is scheduled
to handle it, and
(b) if rtc_timer_do_work() is called to handle expired timers whose
handlers implement a preemption point.

A pending suspend request may be honoured in the above cases causing
timer handling to be delayed until after the next resume. This is
undesirable since timer handlers may have time-critical code to execute.

This patch makes sure that the system stays awake until all expired
timers are handled.

Note that all calls to pm_stay_awake() are eventually paired with
the single pm_relax() call in rtc_timer_do_work(), which is launched
using schedule_work().

Cc: Alessandro Zummo <a.zummo@towertech.it>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Arve Hjonnevag <arve@android.com>
Cc: Todd Poynor <toddpoynor@google.com>
Signed-off-by: Zoran Markovic <zoran.markovic@linaro.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>
This commit is contained in:
Zoran Markovic 2013-06-26 16:09:13 -07:00 committed by John Stultz
parent 07862c1cd6
commit 14d0e347ea
1 changed files with 9 additions and 4 deletions
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13
drivers/rtc/interface.c
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@ -72,6 +72,7 @@ int rtc_set_time(struct rtc_device *rtc, struct rtc_time *tm)
} else
err = -EINVAL;
pm_stay_awake(rtc->dev.parent);
mutex_unlock(&rtc->ops_lock);
/* A timer might have just expired */
schedule_work(&rtc->irqwork);
@ -113,6 +114,7 @@ int rtc_set_mmss(struct rtc_device *rtc, unsigned long secs)
err = -EINVAL;
}
pm_stay_awake(rtc->dev.parent);
mutex_unlock(&rtc->ops_lock);
/* A timer might have just expired */
schedule_work(&rtc->irqwork);
@ -771,9 +773,10 @@ static int rtc_timer_enqueue(struct rtc_device *rtc, struct rtc_timer *timer)
alarm.time = rtc_ktime_to_tm(timer->node.expires);
alarm.enabled = 1;
err = __rtc_set_alarm(rtc, &alarm);
if (err == -ETIME)
if (err == -ETIME) {
pm_stay_awake(rtc->dev.parent);
schedule_work(&rtc->irqwork);
else if (err) {
} else if (err) {
timerqueue_del(&rtc->timerqueue, &timer->node);
timer->enabled = 0;
return err;
@ -818,8 +821,10 @@ static void rtc_timer_remove(struct rtc_device *rtc, struct rtc_timer *timer)
alarm.time = rtc_ktime_to_tm(next->expires);
alarm.enabled = 1;
err = __rtc_set_alarm(rtc, &alarm);
if (err == -ETIME)
if (err == -ETIME) {
pm_stay_awake(rtc->dev.parent);
schedule_work(&rtc->irqwork);
}
}
}
@ -845,7 +850,6 @@ void rtc_timer_do_work(struct work_struct *work)
mutex_lock(&rtc->ops_lock);
again:
pm_relax(rtc->dev.parent);
__rtc_read_time(rtc, &tm);
now = rtc_tm_to_ktime(tm);
while ((next = timerqueue_getnext(&rtc->timerqueue))) {
@ -880,6 +884,7 @@ again:
} else
rtc_alarm_disable(rtc);
pm_relax(rtc->dev.parent);
mutex_unlock(&rtc->ops_lock);
}