linux-kernel - Re: [PATCH v3 1/4] rtc: omap: Cut down the shutdown time from 2 seconds to 1 sec

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Message-ID: <20180711135444.GC12517@localhost>
Date:   Wed, 11 Jul 2018 15:54:44 +0200
From:   Johan Hovold <johan@...nel.org>
To:     Keerthy <j-keerthy@...com>
Cc:     a.zummo@...ertech.it, alexandre.belloni@...tlin.com,
        t-kristo@...com, linux-rtc@...r.kernel.org,
        linux-omap@...r.kernel.org, linux-kernel@...r.kernel.org,
        johan@...nel.org
Subject: Re: [PATCH v3 1/4] rtc: omap: Cut down the shutdown time from 2
 seconds to 1 sec

On Tue, Jul 10, 2018 at 12:20:49PM +0530, Keerthy wrote:
> Cut down the shutdown time from 2 seconds to 1 sec. In case of roll
> over try again.
> 
> Signed-off-by: Keerthy <j-keerthy@...com>
> ---
>  drivers/rtc/rtc-omap.c | 9 +++++++--
>  1 file changed, 7 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/rtc/rtc-omap.c b/drivers/rtc/rtc-omap.c
> index 323ff55..14f2241 100644
> --- a/drivers/rtc/rtc-omap.c
> +++ b/drivers/rtc/rtc-omap.c
> @@ -441,11 +441,12 @@ static void omap_rtc_power_off(void)
>  	val = rtc_readl(rtc, OMAP_RTC_PMIC_REG);
>  	rtc_writel(rtc, OMAP_RTC_PMIC_REG, val | OMAP_RTC_PMIC_POWER_EN_EN);
>  
> -	/* set alarm two seconds from now */
> +again:
> +	/* set alarm one second from now */
>  	omap_rtc_read_time_raw(rtc, &tm);
>  	bcd2tm(&tm);
>  	rtc_tm_to_time(&tm, &now);
> -	rtc_time_to_tm(now + 2, &tm);
> +	rtc_time_to_tm(now + 1, &tm);
>  
>  	if (tm2bcd(&tm) < 0) {
>  		dev_err(&rtc->rtc->dev, "power off failed\n");
> @@ -455,6 +456,10 @@ static void omap_rtc_power_off(void)
>  
>  	rtc_wait_not_busy(rtc);
>  
> +	/* Our calculations started right before the rollover, try again */
> +	if (seconds != rtc_read(omap_rtc_power_off_rtc, OMAP_RTC_SECONDS_REG))
> +		goto again;

First, this doesn't even compile.

Second, nothing is preventing the rollover from happening here after the
check. 

> +
>  	rtc_write(rtc, OMAP_RTC_ALARM2_SECONDS_REG, tm.tm_sec);
>  	rtc_write(rtc, OMAP_RTC_ALARM2_MINUTES_REG, tm.tm_min);
>  	rtc_write(rtc, OMAP_RTC_ALARM2_HOURS_REG, tm.tm_hour);

Johan