Re: [PATCH v3 10/10] pinctrl: Add pin controller driver for AAEON UP boards

Thomas Richard
2025-04-22T14:36:36Z

>> +static int upboard_gpio_request(struct gpio_chip *gc, unsigned int offset)
>> +{
>> + struct gpiochip_fwd *fwd = container_of(gc, struct gpiochip_fwd, chip);
>> + struct upboard_pinctrl *pctrl = fwd->data;
>
> Yeah, something like
>
> struct upboard_pinctrl *pctrl = gpio_fwd_get_data(fwd);
>
>> + unsigned int pin = pctrl->pctrl_data->pin_header[offset];
>> + struct gpio_desc *desc;
>> + int ret;
>> +
>> + ret = pinctrl_gpio_request(gc, offset);
>> + if (ret)
>> + return ret;
>
>> + /* GPIO desc is already registered */
>> + if (fwd->descs[offset])
>> + return 0;
>
> As mentioned in another reply, why 0 and even though, why can't it be simply
> filtered by EEXIST from the below?
>
> In worst scenario, you can add an API gpio_fwd_is_registered(fwd, offset).

I cannot filter using EEXIST, because I have to get the GPIO desc first.
And using the retcode of gpiod_get_index() I cannot detect that I
already requested the GPIO.

As now gpiochip_fwd is an opaque pointer, I will add the
gpio_fwd_is_registered() helper.

It is due to the fact that the forwarder never releases a GPIO desc. An
other solution could be to add the possibility to remove a GPIO desc.
In upboard_gpio_free() the GPIO desc is free, and we can remove the check.

upboard_gpio_free()
{
gpio_fwd_free_desc(fwd, offset);
pinctrl_gpio_free(gc, offset);
}

Best Regards,

Thomas