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SubjectRe: [PATCH] pio: add arch specific gpio_is_valid() function
avictor.za@gmail.com wrote:
> hi,
>
>> NAK still. You're trying to abuse gpio_is_valid(),
>> which I see no need to support.
>>
>> In terms of GPIO framework architecture, zero is
>> the first GPIO in all cases, and is always
>> a valid GPIO number, even if it's not
>> requestable/swritable/readable on a given board.
>>
>> Whether it's usable on a given platform depends
>> on whether a GPIO controller is registered which
>> claims numbers 0..N ... (assuming gpiolib in use).
>
> How should the following be done in a driver then?
>
> if (gpio_is_valid(device->output_pin)) {
> if (gpio_request(device->output_pin, "driverX") != 0)
> goto error_handling;
>
> /* continue with gpio setup */
> }
> else {
> /* there is no vcc_pin, so don't do any gpio setup */

Adding:

device->output_pin = -EINVAL;

Will force the gpio to be invalid here, so that subsequent uses of
gpio_is_valid will behave as expected in the case where
device->output_pin >= 0, but doesn't map to a useable gpio.

> }
>
> ....
>
> if (gpio_is_valid(device->output_pin)) {
> /* set value high */
> }

~Ryan


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