Re: [watchdog v2] watchdog: mei_wdt: request stop on unregister

[Guenter Roeck]

On Sun, Jan 24, 2021 at 01:49:38PM +0200, Tomas Winkler wrote:
> From: Alexander Usyskin <alexander.usyskin@xxxxxxxxx>
> 
> The MEI bus has a special behavior on suspend it destroys
> all the attached devices, this is due to the fact that also
> firmware context is not persistent across power flows.
> 
> If watchdog on MEI bus is ticking before suspending the firmware
> times out and reports that the OS is missing watchdog tick.
> Send the stop command to the firmware on watchdog unregistered
> to eliminate the false event on suspend.
> This does not make the things worse from the user-space perspective
> as a user-space should re-open watchdog device after
> suspending before this patch.
> 
> Cc: <stable@xxxxxxxxxxxxxxx>
> Signed-off-by: Alexander Usyskin <alexander.usyskin@xxxxxxxxx>
> Signed-off-by: Tomas Winkler <tomas.winkler@xxxxxxxxx>

Reviewed-by: Guenter Roeck <linux@xxxxxxxxxxxx>

> ---
> V2: Update the commit message with better explanation
> 
>  drivers/watchdog/mei_wdt.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/watchdog/mei_wdt.c b/drivers/watchdog/mei_wdt.c
> index 5391bf3e6b11..c5967d8b4256 100644
> --- a/drivers/watchdog/mei_wdt.c
> +++ b/drivers/watchdog/mei_wdt.c
> @@ -382,6 +382,7 @@ static int mei_wdt_register(struct mei_wdt *wdt)
>  
>  	watchdog_set_drvdata(&wdt->wdd, wdt);
>  	watchdog_stop_on_reboot(&wdt->wdd);
> +	watchdog_stop_on_unregister(&wdt->wdd);
>  
>  	ret = watchdog_register_device(&wdt->wdd);
>  	if (ret)
> -- 
> 2.26.2
>