linux-kernel - Re: [PATCH v2 2/2] watchdog: imx2_wdg: notify wdog core to stop ping worker on suspend

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Date:   Mon, 28 Jun 2021 07:02:51 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Grzegorz Jaszczyk <grzegorz.jaszczyk@...aro.org>
Cc:     wim@...ux-watchdog.org, shawnguo@...nel.org,
        linux-watchdog@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Michal Koziel <michal.koziel@...ogic.no>
Subject: Re: [PATCH v2 2/2] watchdog: imx2_wdg: notify wdog core to stop ping
 worker on suspend

On Fri, Jun 18, 2021 at 09:50:33PM +0200, Grzegorz Jaszczyk wrote:
> Suspend routine disables wdog clk. Nevertheless, the watchdog subsystem
> is not aware of that and can still try to ping wdog through
> watchdog_ping_work. In order to prevent such condition and therefore
> prevent from system hang (caused by the wdog register access issued
> while the wdog clock is disabled) notify watchdog core that the ping
> worker should be canceled during watchdog core suspend and restored
> during resume.
> 
> Signed-off-by: Michal Koziel <michal.koziel@...ogic.no>
> Signed-off-by: Grzegorz Jaszczyk <grzegorz.jaszczyk@...aro.org>

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

> ---
> v1->v2:
> - Do not use watchdog_dev_suspend/resume directly, instead notify the
> watchdog core that the ping worker should be canceled during watchdog
> core suspend and restored during resume.
> - Commit log was updated accordingly.
> ---
>  drivers/watchdog/imx2_wdt.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/watchdog/imx2_wdt.c b/drivers/watchdog/imx2_wdt.c
> index b84f80f7d342..3e8d9c3b6386 100644
> --- a/drivers/watchdog/imx2_wdt.c
> +++ b/drivers/watchdog/imx2_wdt.c
> @@ -311,6 +311,7 @@ static int __init imx2_wdt_probe(struct platform_device *pdev)
>  	watchdog_set_nowayout(wdog, nowayout);
>  	watchdog_set_restart_priority(wdog, 128);
>  	watchdog_init_timeout(wdog, timeout, dev);
> +	watchdog_stop_ping_on_suspend(wdog);
>  
>  	if (imx2_wdt_is_running(wdev)) {
>  		imx2_wdt_set_timeout(wdog, wdog->timeout);