Re: [PATCH 2/3] drm/sitronix/st7571-i2c: Make the reset GPIO to be optional

[Javier Martinez Canillas <javierm@redhat.com>]

Marcus Folkesson <marcus.folkesson@gmail.com> writes:

Hello Marcus,

> Hello Javier,
>
> On Thu, Jul 10, 2025 at 01:00:41PM +0200, Javier Martinez Canillas wrote:
>> >
>> > devm_gpiod_get_optional() returns -ENOENT when the GPIO is not found,
>> > and that is no error we want to propagage upwards.
>> >
>> > Maybe something like this instead:
>> > if (IS_ERR(st7571->reset) && IS_ERR(st7571->reset) != -ENOENT)
>> >
>> 
>> Are you sure about that? As far as I know, that is exactly the
>> difference between gpiod_get() and gpiod_get_optional() variants.
>> 
>> From the gpiod_get_optional() function helper kernel-doc [0]:
>> 
>> /**
>>  * gpiod_get_optional - obtain an optional GPIO for a given GPIO function
>>  * @dev: GPIO consumer, can be NULL for system-global GPIOs
>>  * @con_id: function within the GPIO consumer
>>  * @flags: optional GPIO initialization flags
>>  *
>>  * This is equivalent to gpiod_get(), except that when no GPIO was assigned to
>>  * the requested function it will return NULL. This is convenient for drivers
>>  * that need to handle optional GPIOs.
>>  *
>>  * Returns:
>>  * The GPIO descriptor corresponding to the function @con_id of device
>>  * dev, NULL if no GPIO has been assigned to the requested function, or
>>  * another IS_ERR() code if an error occurred while trying to acquire the GPIO.
>>  */
>> 
>> while the gpiod_get() kernel-doc says the following:
>> 
>> /**
>>  * gpiod_get - obtain a GPIO for a given GPIO function
>>  * @dev:	GPIO consumer, can be NULL for system-global GPIOs
>>  * @con_id:	function within the GPIO consumer
>>  * @flags:	optional GPIO initialization flags
>>  *
>>  * Returns:
>>  * The GPIO descriptor corresponding to the function @con_id of device
>>  * dev, -ENOENT if no GPIO has been assigned to the requested function, or
>>  * another IS_ERR() code if an error occurred while trying to acquire the GPIO.
>>  */
>> 
>
> You are completely righ.
>
> Reviewed-by: Marcus Folkesson <marcus.folkesson@gmail.com>
>

Thanks for your review! Do you plan to look at the other patches too ?

-- 
Best regards,

Javier Martinez Canillas
Core Platforms
Red Hat