Re: [PATCH] gpiolib: don't bail out if get_direction() fails in gpiochip_add_data()

[Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>]

On 19.02.2025 15:43, Bartosz Golaszewski wrote:
> From: Bartosz Golaszewski <bartosz.golaszewski@xxxxxxxxxx>
>
> Since commit 9d846b1aebbe ("gpiolib: check the return value of
> gpio_chip::get_direction()") we check the return value of the
> get_direction() callback as per its API contract. Some drivers have been
> observed to fail to register now as they may call get_direction() in
> gpiochip_add_data() in contexts where it has always silently failed.
> Until we audit all drivers, replace the bail-out to a kernel log
> warning.
>
> Fixes: 9d846b1aebbe ("gpiolib: check the return value of gpio_chip::get_direction()")
> Reported-by: Mark Brown <broonie@xxxxxxxxxx>
> Closes: https://lore.kernel.org/all/Z7VFB1nST6lbmBIo@xxxxxxxxxxxxxxxxxxxxxxxx/
> Reported-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
> Closes: https://lore.kernel.org/all/dfe03f88-407e-4ef1-ad30-42db53bbd4e4@xxxxxxxxxxx/
> Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@xxxxxxxxxx>

Tested-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>

This fixes the issue observed on RPi boards without any changes to 
gpio/pinctrl driver.

> ---
>   drivers/gpio/gpiolib.c | 10 +++++++++-
>   1 file changed, 9 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
> index 704452fd94bb..48cf1bb23e24 100644
> --- a/drivers/gpio/gpiolib.c
> +++ b/drivers/gpio/gpiolib.c
> @@ -1060,7 +1060,15 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc, void *data,
>   		if (gc->get_direction && gpiochip_line_is_valid(gc, desc_index)) {
>   			ret = gc->get_direction(gc, desc_index);
>   			if (ret < 0)
> -				goto err_cleanup_desc_srcu;
> +				/*
> +				 * FIXME: Bail-out here once all GPIO drivers
> +				 * are updated to not return errors in
> +				 * situations that can be considered normal
> +				 * operation.
> +				 */
> +				dev_warn(&gdev->dev,
> +					 "%s: get_direction failed: %d\n",
> +					 __func__, ret);
>   
>   			assign_bit(FLAG_IS_OUT, &desc->flags, !ret);
>   		} else {

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland