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

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Date:   Sat, 4 Mar 2023 08:16:59 -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 3/4/23 06:54, Guenter Roeck wrote:
> 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.
> 

I just sent a patch which fixes the problem in the watchdog core.

Guenter

> 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;
>