linux-kernel - Re: [PATCH v4 1/2] watchdog: Add a new flag WDIOF_STOP

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Date: Thu, 6 Mar 2025 09:40:50 +0000
From: George Cherian <gcherian@...vell.com>
To: Julius Werner <jwerner@...omium.org>
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Subject: Re: [PATCH v4 1/2] watchdog: Add a new flag WDIOF_STOP_MAYSLEEP

Hi Julius,
>>  static const struct watchdog_ops adv_ec_wdt_ops = {
>> diff --git a/drivers/watchdog/arm_smc_wdt.c b/drivers/watchdog/arm_smc_wdt.c
>> index 8f3d0c3a005f..794cf0086912 100644
>> --- a/drivers/watchdog/arm_smc_wdt.c
>> +++ b/drivers/watchdog/arm_smc_wdt.c
>> @@ -90,7 +90,8 @@ static const struct watchdog_info smcwd_info = {
>>         .identity       = DRV_NAME,
>>         .options        = WDIOF_SETTIMEOUT |
>>                           WDIOF_KEEPALIVEPING |
>> -                         WDIOF_MAGICCLOSE,
>> +                         WDIOF_MAGICCLOSE |
>> +                         WDIOF_STOP_MAYSLEEP,
>>  };
>
>I don't think this driver can sleep, unless I'm missing something?

The only reason I added to avoid any inadvertent hang in TF-A.
Anyways the approach is going to change so this patch is not 
needed anymore.
>`arm_smccc_smc()` does a synchronous call into firmware that always
>returns back to the caller.

Thanks for the insight.
-George