linux-kernel - Re: [PATCH v2 1/2] rtc-cmos: Ensure no expired alarm is left enabled after resume

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Date:   Tue, 6 Sep 2016 00:26:56 +0200
From:   Alexandre Belloni <alexandre.belloni@...e-electrons.com>
To:     Gabriele Mazzotta <gabriele.mzt@...il.com>
Cc:     a.zummo@...ertech.it, rtc-linux@...glegroups.com,
        linux-kernel@...r.kernel.org, matthew.garrett@...ula.com
Subject: Re: [PATCH v2 1/2] rtc-cmos: Ensure no expired alarm is left enabled
 after resume

Hi

On 01/09/2016 at 00:58:59 +0200, Gabriele Mazzotta wrote :
>  static int cmos_resume(struct device *dev)
>  {
>  	struct cmos_rtc	*cmos = dev_get_drvdata(dev);
>  	unsigned char tmp;
> +	bool is_wkalrm_expired;
>  
>  	if (cmos->enabled_wake) {
>  		if (cmos->wake_off)
> @@ -913,6 +935,8 @@ static int cmos_resume(struct device *dev)
>  		cmos->enabled_wake = 0;
>  	}
>  
> +	is_wkalrm_expired = cmos_is_wkalrm_expired(dev);
> +
>  	spin_lock_irq(&rtc_lock);
>  	tmp = cmos->suspend_ctrl;
>  	cmos->suspend_ctrl = 0;
> @@ -939,6 +963,17 @@ static int cmos_resume(struct device *dev)
>  			tmp &= ~RTC_AIE;
>  			hpet_mask_rtc_irq_bit(RTC_AIE);
>  		} while (mask & RTC_AIE);
> +
> +		/*
> +		 * If RTC_AIE is set and we have an alarm set to go off in the
> +		 * past, then the BIOS woke the system when the alarm went off
> +		 * and we now have to clear it.
> +		 */
> +		if ((tmp & RTC_AIE) && is_wkalrm_expired) {

Is there any issue dropping is_wkalrm_expired and calling
cmos_is_wkalrm_expired() here? That would avoid calling
cmos_is_wkalrm_expired on each wakeup.

-- 
Alexandre Belloni, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com