Re: [PATCH] rtc: ds1374: wdt:support suspend/resume for watchdog

[Guenter Roeck <linux@roeck-us.net>]

On 09/26/2017 03:22 AM, Alexandre Belloni wrote:
> (+Cc wdt maintainers)
> 
> On 26/09/2017 at 09:56:32 +0800, 18502523564 wrote:
>> Hi Alexandre,
>>
>> Thanks for your reply.
>> Do you think is this a issue when using as a watchdog in suspend?
>> I takes the drivers/watchdog/ subsystem for reference, some drivers in suspend
>> also call disable_watchdog.Or do you have any  better suggestion?
> 
> I guess this is a question for the watchdog subsystem maintainers.
> However, I think that everything can be handled properly from userspace
> as I know some atmel based devices have their watchdog enabled while
> the platform is suspended.
> 

Depends on the driver, really. There is one thing wrong below, though:
It appears that on resume, the watchdog is unconditionally enabled.

Guenter

>> Thank you.
>>
>>
>>
>>
>> ------------------ Original ------------------
>> From: Alexandre Belloni <alexandre.belloni@free-electrons.com>
>> Date: 周一,9月 25,2017 20:07
>> To: winton.liu <18502523564@163.com>
>> Cc: a.zummo <a.zummo@towertech.it>, linux-rtc <linux-rtc@vger.kernel.org>,
>> linux-kernel <linux-kernel@vger.kernel.org>
>> Subject: Re: [PATCH] rtc: ds1374: wdt:support suspend/resume for watchdog
>>
>>
>> Hi,
>>
>> On 25/09/2017 at 19:58:44 +0800, winton.liu wrote:
>>> When enable CONFIG_RTC_DRV_DS1374_WDT use as watchdog,
>>> in suspend mode, watchdog is still working but no daemon
>>> patting the watchdog. The system will reboot if timeout.
>>> So disable watchdog in suspend  and recover it in resume.
>>>
>>
>> That is definitively not what we want. Many people will want to still
>> have the watchdog running when the platform is suspended. Your options
>> are to either disable the watchdog before going to suspend or wake up
>> the platform just in time to ping the watchdog.
>>
>>> Signed-off-by: winton.liu <18502523564@163.com>
>>> ---
>>>   drivers/rtc/rtc-ds1374.c | 8 ++++++++
>>>   1 file changed, 8 insertions(+)
>>>
>>> diff --git a/drivers/rtc/rtc-ds1374.c b/drivers/rtc/rtc-ds1374.c
>>> index 38a2e9e..e990773 100644
>>> --- a/drivers/rtc/rtc-ds1374.c
>>> +++ b/drivers/rtc/rtc-ds1374.c
>>> @@ -690,6 +690,10 @@ static int ds1374_suspend(struct device *dev)
>>>   {
>>>        struct i2c_client *client = to_i2c_client(dev);
>>>
>>> +#ifdef CONFIG_RTC_DRV_DS1374_WDT
>>> +     ds1374_wdt_disable();
>>> +#endif
>>> +
>>>        if (client->irq > 0 && device_may_wakeup(&client->dev))
>>>                enable_irq_wake(client->irq);
>>>        return 0;
>>> @@ -699,6 +703,10 @@ static int ds1374_resume(struct device *dev)
>>>   {
>>>        struct i2c_client *client = to_i2c_client(dev);
>>>
>>> +#ifdef CONFIG_RTC_DRV_DS1374_WDT
>>> +     ds1374_wdt_settimeout(131072);
>>> +#endif
>>> +
>>>        if (client->irq > 0 && device_may_wakeup(&client->dev))
>>>                disable_irq_wake(client->irq);
>>>        return 0;
>>> --
>>> 1.9.1
>>>
>>>
>>
>> --
>> Alexandre Belloni, Free Electrons
>> Embedded Linux and Kernel engineering
>> http://free-electrons.com
>>
>