linux-kernel - Re: [PATCH v6 10/24] watchdog: jz4740: Avoid starting watchdog in set

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Date:   Fri, 10 Aug 2018 06:37:35 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Paul Cercueil <paul@...pouillou.net>
Cc:     Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Thierry Reding <thierry.reding@...il.com>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Wim Van Sebroeck <wim@...ux-watchdog.org>,
        Ralf Baechle <ralf@...ux-mips.org>,
        Paul Burton <paul.burton@...s.com>,
        James Hogan <jhogan@...nel.org>,
        Jonathan Corbet <corbet@....net>,
        Lee Jones <lee.jones@...aro.org>,
        Mathieu Malaterre <malat@...ian.org>,
        Ezequiel Garcia <ezequiel@...labora.co.uk>,
        linux-pwm@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-watchdog@...r.kernel.org,
        linux-mips@...ux-mips.org, linux-doc@...r.kernel.org,
        linux-clk@...r.kernel.org
Subject: Re: [PATCH v6 10/24] watchdog: jz4740: Avoid starting watchdog in
 set_timeout

On Thu, Aug 09, 2018 at 11:44:00PM +0200, Paul Cercueil wrote:
> Previously the jz4740_wdt_set_timeout() function was starting the timer
> unconditionally, even if it was stopped when that function was entered.
> 
> Now, the timer will be restarted only if it was already running before
> this function is called.
> 
> Signed-off-by: Paul Cercueil <paul@...pouillou.net>

Reviewed-by: Guenter Roeck <linux@...ck-us.net>

> ---
>  drivers/watchdog/jz4740_wdt.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
>  v6: New patch
> 
> diff --git a/drivers/watchdog/jz4740_wdt.c b/drivers/watchdog/jz4740_wdt.c
> index 0f54306aee25..45d9495170e5 100644
> --- a/drivers/watchdog/jz4740_wdt.c
> +++ b/drivers/watchdog/jz4740_wdt.c
> @@ -64,13 +64,15 @@ static int jz4740_wdt_set_timeout(struct watchdog_device *wdt_dev,
>  {
>  	struct jz4740_wdt_drvdata *drvdata = watchdog_get_drvdata(wdt_dev);
>  	u16 timeout_value = (u16)(drvdata->clk_rate * new_timeout);
> +	u32 tcer;
>  
> +	regmap_read(drvdata->map, TCU_REG_WDT_TCER, &tcer);
>  	regmap_write(drvdata->map, TCU_REG_WDT_TCER, 0);
>  
>  	regmap_write(drvdata->map, TCU_REG_WDT_TDR, timeout_value);
>  	regmap_write(drvdata->map, TCU_REG_WDT_TCNT, 0);
>  
> -	regmap_write(drvdata->map, TCU_REG_WDT_TCER, TCU_WDT_TCER_TCEN);
> +	regmap_write(drvdata->map, TCU_REG_WDT_TCER, tcer & TCU_WDT_TCER_TCEN);
>  
>  	wdt_dev->timeout = new_timeout;
>  	return 0;
> @@ -86,6 +88,7 @@ static int jz4740_wdt_start(struct watchdog_device *wdt_dev)
>  		return ret;
>  
>  	jz4740_wdt_set_timeout(wdt_dev, wdt_dev->timeout);
> +	regmap_write(drvdata->map, TCU_REG_WDT_TCER, TCU_WDT_TCER_TCEN);
>  
>  	return 0;
>  }
> -- 
> 2.11.0
>