linux-kernel - Re: [PATCH -next] watchdog: sbsa: Test WDOG_HW

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Message-ID: <8aff260c-7151-fe1c-91cd-1e107225a25f@roeck-us.net>
Date:   Sat, 4 Mar 2023 06:54:58 -0800
From:   Guenter Roeck <linux@...ck-us.net>
To:     Wang Wensheng <wangwensheng4@...wei.com>, wim@...ux-watchdog.org,
        linux-watchdog@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     xuqiang36@...wei.com
Subject: Re: [PATCH -next] watchdog: sbsa: Test WDOG_HW_RUNNING bit in suspend
 and resume

On 3/1/23 03:37, Wang Wensheng wrote:
> If the sbsa_gwdt is enabled by BIOS, the kernel set WDOG_HW_RUNNING bit
> and keep it alive before anyone else would open it. When system suspend,
> the sbsa_gwdt would not be disabled because WDOG_ACTIVE is not set. Then
> the sbsa_gwdt would reach timeout since no one touch it during system
> suspend.
> 
> To solve this, just test WDOG_HW_RUNNING bit in suspend and disable the
> sbsa_gwdt if the bit is set, then reopen it accordingly in resume
> process.
> 
> Signed-off-by: Wang Wensheng <wangwensheng4@...wei.com>
> ---
>   drivers/watchdog/sbsa_gwdt.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/watchdog/sbsa_gwdt.c b/drivers/watchdog/sbsa_gwdt.c
> index 9791c74aebd4..60875a710e43 100644
> --- a/drivers/watchdog/sbsa_gwdt.c
> +++ b/drivers/watchdog/sbsa_gwdt.c
> @@ -360,7 +360,7 @@ static int __maybe_unused sbsa_gwdt_suspend(struct device *dev)
>   {
>   	struct sbsa_gwdt *gwdt = dev_get_drvdata(dev);
>   
> -	if (watchdog_active(&gwdt->wdd))
> +	if (watchdog_hw_running(&gwdt->wdd))
>   		sbsa_gwdt_stop(&gwdt->wdd);

That will not stop the watchdog if it is currently open (active)
and if it wasn't running when the module was loaded.

Guenter

>   
>   	return 0;
> @@ -371,7 +371,7 @@ static int __maybe_unused sbsa_gwdt_resume(struct device *dev)
>   {
>   	struct sbsa_gwdt *gwdt = dev_get_drvdata(dev);
>   
> -	if (watchdog_active(&gwdt->wdd))
> +	if (watchdog_hw_running(&gwdt->wdd))
>   		sbsa_gwdt_start(&gwdt->wdd);
>   
>   	return 0;