linux-kernel - Re: [PATCH v1] watchdog: starfive: Fix the probe return error if PM and early

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Date:   Tue, 25 Apr 2023 19:01:52 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Xingyu Wu <xingyu.wu@...rfivetech.com>,
        linux-watchdog@...r.kernel.org,
        Wim Van Sebroeck <wim@...ux-watchdog.org>
Cc:     Samin Guo <samin.guo@...rfivetech.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1] watchdog: starfive: Fix the probe return error if PM
 and early_enable are both disabled

On 4/25/23 18:49, Xingyu Wu wrote:
> On 2023/4/25 22:06, Guenter Roeck wrote:
>> On 4/25/23 03:04, Xingyu Wu wrote:
>>> When the starfive watchdog driver uses 'pm_runtime_put_sync()' as probe
>>> return value at last and 'early_enable' is disabled, it could return the
>>> error '-ENOSYS' if the CONFIG_PM is disabled, but the driver should works
>>> normally.
>>>
>>> Add a check to make sure the PM is enabled and then use
>>> 'pm_runtime_put_sync()' as return value when 'early_enable' is disabled.
>>>
>>> Fixes: db728ea9c7be ("drivers: watchdog: Add StarFive Watchdog driver")
>>> Signed-off-by: Xingyu Wu <xingyu.wu@...rfivetech.com>
>>> ---
>>>
>>> Hi, Guenter and Wim,
>>>
>>> This patch fixes the issue of StarFive watchdog driver and rebases on
>>> the master branch of linux-next.
>>>
>>> Thanks.
>>>    ---
>>>    drivers/watchdog/starfive-wdt.c | 3 ++-
>>>    1 file changed, 2 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/watchdog/starfive-wdt.c b/drivers/watchdog/starfive-wdt.c
>>> index 1995cceca51e..51e487e09960 100644
>>> --- a/drivers/watchdog/starfive-wdt.c
>>> +++ b/drivers/watchdog/starfive-wdt.c
>>> @@ -492,7 +492,8 @@ static int starfive_wdt_probe(struct platform_device *pdev)
>>>            goto err_exit;
>>>          if (!early_enable)
>>> -        return pm_runtime_put_sync(&pdev->dev);
>>> +        if (pm_runtime_enabled(&pdev->dev))
>>> +            return pm_runtime_put_sync(&pdev->dev);
>>>    
>>
>> Why not just
>>
>>      if (!early_enable)
>>          pm_runtime_put_sync(&pdev->dev)
>>
>> like almost every other caller of pm_runtime_put_sync() ?
>>
> 
> The function of pm_runtime_put_sync() is that:
> 
> static inline int pm_runtime_put_sync(struct device *dev)
> {
> 	return __pm_runtime_idle(dev, RPM_GET_PUT);
> }
> 
> and when do not enable CONFIG_PM, the __pm_runtime_idle() is that:
> 
> static inline int __pm_runtime_idle(struct device *dev, int rpmflags)
> {
> 	return -ENOSYS;
> }
> 
> If I do not open PM, it will return error saying probe failed
> but it works fine without PM. I had tested that and probe really
> was failed. So I should add this check before using pm_runtime_put_sync().
> 

You did not answer my question.

Guenter