Re: [PATCH] watchdog: bcm2835_wdt: Fix WDIOC_SETTIMEOUT handling

[Guenter Roeck <linux@roeck-us.net>]

On Sun, Nov 12, 2023 at 06:32:51PM +0100, Stefan Wahren wrote:
> Users report about the unexpected behavior for setting timeouts above
> 15 sec on Raspberry Pi. According to watchdog-api.rst the ioctl
> WDIOC_SETTIMEOUT shouldn't fail because of hardware limitations.
> But looking at the code shows that max_timeout based on the
> register value PM_WDOG_TIME_SET, which is the maximum.
> 
> Since 664a39236e71 ("watchdog: Introduce hardware maximum heartbeat
> in watchdog core") the watchdog core is able to handle this problem.
> 
> This fix has been tested with watchdog-test from selftests.
> 
> Link: https://bugzilla.kernel.org/show_bug.cgi?id=217374
> Fixes: 664a39236e71 ("watchdog: Introduce hardware maximum heartbeat in watchdog core")
> Signed-off-by: Stefan Wahren <wahrenst@gmx.net>

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

> ---
>  drivers/watchdog/bcm2835_wdt.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/watchdog/bcm2835_wdt.c b/drivers/watchdog/bcm2835_wdt.c
> index 7a855289ff5e..bb001c5d7f17 100644
> --- a/drivers/watchdog/bcm2835_wdt.c
> +++ b/drivers/watchdog/bcm2835_wdt.c
> @@ -42,6 +42,7 @@
> 
>  #define SECS_TO_WDOG_TICKS(x) ((x) << 16)
>  #define WDOG_TICKS_TO_SECS(x) ((x) >> 16)
> +#define WDOG_TICKS_TO_MSECS(x) ((x) * 1000 >> 16)
> 
>  struct bcm2835_wdt {
>  	void __iomem		*base;
> @@ -140,7 +141,7 @@ static struct watchdog_device bcm2835_wdt_wdd = {
>  	.info =		&bcm2835_wdt_info,
>  	.ops =		&bcm2835_wdt_ops,
>  	.min_timeout =	1,
> -	.max_timeout =	WDOG_TICKS_TO_SECS(PM_WDOG_TIME_SET),
> +	.max_hw_heartbeat_ms =	WDOG_TICKS_TO_MSECS(PM_WDOG_TIME_SET),
>  	.timeout =	WDOG_TICKS_TO_SECS(PM_WDOG_TIME_SET),
>  };
> 
> --
> 2.34.1
>