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

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

[Tomas Winkler]

From: Alexander Usyskin <alexander.usyskin@intel.com>

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@vger.kernel.org>
Signed-off-by: Alexander Usyskin <alexander.usyskin@intel.com>
Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
---
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

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@intel.com>
> 
> 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@vger.kernel.org>
> Signed-off-by: Alexander Usyskin <alexander.usyskin@intel.com>
> Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>

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

> ---
> 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
>