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Commit 14d0e347 authored by Zoran Markovic's avatar Zoran Markovic Committed by John Stultz
Browse files

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



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: default avatarZoran Markovic <zoran.markovic@linaro.org>
Signed-off-by: default avatarJohn Stultz <john.stultz@linaro.org>
parent 07862c1c

drivers/rtc/interface.c

+9 −4
Original line number Diff line number Diff line
@@ -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;
@@ -818,10 +821,12 @@ 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);

		}

	}

}



/**

 * rtc_timer_do_work - Expires rtc timers
@@ -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 @@ void rtc_timer_do_work(struct work_struct *work) 
	} else

		rtc_alarm_disable(rtc);



	pm_relax(rtc->dev.parent);

	mutex_unlock(&rtc->ops_lock);

}