linux-kernel - Re: System automatically wakes up because of Intel Rapid Start Technology

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Message-ID: <6760597.z8zpCLmhLz@xps13>
Date:	Mon, 22 Dec 2014 19:57:25 +0100
From:	Gabriele Mazzotta <gabriele.mzt@...il.com>
To:	Matthew Garrett <mjg59@...f.ucam.org>
Cc:	platform-driver-x86@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: System automatically wakes up because of Intel Rapid Start Technology

On Monday 22 December 2014 19:41:52 Gabriele Mazzotta wrote:
> On Monday 22 December 2014 18:02:54 Matthew Garrett wrote:
> > Getting this right is a little bit annoying - if the timer would have 
> > expired during the time we were suspended, we don't want to re-enable 
> > it. I *think* this covers all cases, and does it in generic code rather 
> > than special-casing it. Any chance you can give it a test?
> 
> I've done a quick test. has_persistent_clock() is false on my system,
> so this patch has no effect as it is.

I did another quick test and moved the code so that it is executed
before has_persistent_clock() is checked. Everything seems to be
working as intended. I tried to suspend and resume multiple times
within one minute and exactly one minute after the last suspension
the system transitioned from S3 to S4.

I haven't checked properly whether it is OK or not to simply move
the code or not, but I wanted to let you know that it works.

> > diff --git a/drivers/rtc/class.c b/drivers/rtc/class.c
> > index 472a5ad..4e3a2a1 100644
> > --- a/drivers/rtc/class.c
> > +++ b/drivers/rtc/class.c
> > @@ -91,6 +91,8 @@ static int rtc_suspend(struct device *dev)
> >  		old_system = timespec64_sub(old_system, delta_delta);
> >  	}
> >  
> > +	rtc->valid_alarm = !rtc_read_alarm(rtc, &rtc->alarm);
> > +
> >  	return 0;
> >  }
> >  
> > @@ -145,6 +147,29 @@ static int rtc_resume(struct device *dev)
> >  	if (sleep_time.tv_sec >= 0)
> >  		timekeeping_inject_sleeptime64(&sleep_time);
> >  	rtc_hctosys_ret = 0;
> > +
> > +	/*
> > +	 * If there was an alarm set before suspend, make sure that the
> > +	 * platform hasn't overwritten it
> > +	 */
> > +	if (rtc->valid_alarm) {
> > +		struct rtc_time tm;
> > +		long now, scheduled;
> > +
> > +		rtc_read_time(rtc, &tm);
> > +		rtc_tm_to_time(&rtc->alarm.time, &scheduled);
> > +		rtc_tm_to_time(&tm, &now);
> > +
> > +		/* Clear the alarm if it went off during suspend */
> > +		if (scheduled <= now) {
> > +			rtc_time_to_tm(0, &rtc->alarm.time);
> > +			rtc->alarm.enabled = 0;
> > +		}
> > +
> > +		if (rtc->ops && rtc->ops->set_alarm)
> > +			rtc->ops->set_alarm(rtc->dev.parent, &rtc->alarm);
> > +	}
> > +
> >  	return 0;
> >  }
> >  
> > diff --git a/include/linux/rtc.h b/include/linux/rtc.h
> > index 6d6be09..bc805ff 100644
> > --- a/include/linux/rtc.h
> > +++ b/include/linux/rtc.h
> > @@ -133,6 +133,10 @@ struct rtc_device
> >  	/* Some hardware can't support UIE mode */
> >  	int uie_unsupported;
> >  
> > +#ifdef CONFIG_PM_SLEEP
> > +	struct rtc_wkalrm alarm;
> > +	bool valid_alarm;
> > +#endif
> >  #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
> >  	struct work_struct uie_task;
> >  	struct timer_list uie_timer;
> > 
> > 
> > 

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