linux-kernel - Re: [PATCH v2 2/3] watchdog: sama5d4: Fix setting timeout when watchdog is disabled

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Date:   Fri, 17 Feb 2017 06:40:33 -0800
From:   Guenter Roeck <linux@...ck-us.net>
To:     Alexandre Belloni <alexandre.belloni@...e-electrons.com>
Cc:     Wim Van Sebroeck <wim@...ana.be>,
        Nicolas Ferre <nicolas.ferre@...el.com>,
        linux-watchdog@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 2/3] watchdog: sama5d4: Fix setting timeout when
 watchdog is disabled

On 02/16/2017 11:30 AM, Alexandre Belloni wrote:
> The datasheet states: "When setting the WDDIS bit, and while it is set, the
> fields WDV and WDD must not be modified."
>
> Ensure WDDIS is not set when changing the timeout and set it afterwards if
> the watchdog was disabled.
>
> Signed-off-by: Alexandre Belloni <alexandre.belloni@...e-electrons.com>
> ---
> Changes in v2:
>  - new patch
>  drivers/watchdog/sama5d4_wdt.c | 9 ++++++++-
>  1 file changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/watchdog/sama5d4_wdt.c b/drivers/watchdog/sama5d4_wdt.c
> index 2c6f5a70ae67..2a60251806d2 100644
> --- a/drivers/watchdog/sama5d4_wdt.c
> +++ b/drivers/watchdog/sama5d4_wdt.c
> @@ -90,11 +90,18 @@ static int sama5d4_wdt_set_timeout(struct watchdog_device *wdd,
>  	u32 reg;
>
>  	reg = wdt_read(wdt, AT91_WDT_MR);
> +
> +	if (reg & AT91_WDT_WDDIS)
> +		wdt_write(wdt, AT91_WDT_MR, reg & ~AT91_WDT_WDDIS);
> +
>  	reg &= ~AT91_WDT_WDV;
>  	reg &= ~AT91_WDT_WDD;
>  	reg |= AT91_WDT_SET_WDV(value);
>  	reg |= AT91_WDT_SET_WDD(value);
> -	wdt_write(wdt, AT91_WDT_MR, reg);
> +	wdt_write(wdt, AT91_WDT_MR, reg & ~AT91_WDT_WDDIS);
> +
> +	if (reg & AT91_WDT_WDDIS)
> +		wdt_write(wdt, AT91_WDT_MR, reg);
>
That means if the watchdog is running, the timeout would not be updated.
It should be updated no matter if it is running or not.

Guenter

>  	wdd->timeout = timeout;
>
>