linux-kernel - Re: [PATCH] watchdog: sama5d4: fix WDD value to be always set to max

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Date:   Wed, 8 May 2019 09:34:05 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Eugen.Hristev@...rochip.com
Cc:     Nicolas.Ferre@...rochip.com, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, wim@...ux-watchdog.org,
        linux-watchdog@...r.kernel.org
Subject: Re: [PATCH] watchdog: sama5d4: fix WDD value to be always set to max

On Wed, May 08, 2019 at 02:15:03PM +0000, Eugen.Hristev@...rochip.com wrote:
> From: Eugen Hristev <eugen.hristev@...rochip.com>
> 
> WDD value must be always set to max (0xFFF) otherwise the hardware
> block will reset the board on the first ping of the watchdog.
> 
Not sure why setting WDD to the same value as WDV would do that,
but on the other side it looks like setting WDD to anything but
the maximum doesn't add any value either, so

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

Guenter

> Signed-off-by: Eugen Hristev <eugen.hristev@...rochip.com>
> ---
>  drivers/watchdog/sama5d4_wdt.c | 4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
> 
> diff --git a/drivers/watchdog/sama5d4_wdt.c b/drivers/watchdog/sama5d4_wdt.c
> index 1e93c1b..d495336 100644
> --- a/drivers/watchdog/sama5d4_wdt.c
> +++ b/drivers/watchdog/sama5d4_wdt.c
> @@ -111,9 +111,7 @@ static int sama5d4_wdt_set_timeout(struct watchdog_device *wdd,
>  	u32 value = WDT_SEC2TICKS(timeout);
>  
>  	wdt->mr &= ~AT91_WDT_WDV;
> -	wdt->mr &= ~AT91_WDT_WDD;
>  	wdt->mr |= AT91_WDT_SET_WDV(value);
> -	wdt->mr |= AT91_WDT_SET_WDD(value);
>  
>  	/*
>  	 * WDDIS has to be 0 when updating WDD/WDV. The datasheet states: When
> @@ -251,7 +249,7 @@ static int sama5d4_wdt_probe(struct platform_device *pdev)
>  
>  	timeout = WDT_SEC2TICKS(wdd->timeout);
>  
> -	wdt->mr |= AT91_WDT_SET_WDD(timeout);
> +	wdt->mr |= AT91_WDT_SET_WDD(WDT_SEC2TICKS(MAX_WDT_TIMEOUT));
>  	wdt->mr |= AT91_WDT_SET_WDV(timeout);
>  
>  	ret = sama5d4_wdt_init(wdt);
> -- 
> 2.7.4
>