Re: [PATCH v3] iio: adc: Correct conditional logic for store mode

Nuno Sá
2025-04-15T09:13:55Z

On Mon, 2025-04-14 at 11:40 -0400, Gabriel Shahrouzi wrote:
> The mode setting logic in ad7816_store_mode was reversed due to
> incorrect handling of the strcmp return value. strcmp returns 0 on
> match, so the `if (strcmp(buf, "full"))` block executed when the
> input was not "full".
>
> This resulted in "full" setting the mode to AD7816_PD (power-down) and
> other inputs setting it to AD7816_FULL.
>
> Fix this by checking it against 0 to correctly check for "full" and
> "power-down", mapping them to AD7816_FULL and AD7816_PD respectively.
>
> Fixes: 7924425db04a ("staging: iio: adc: new driver for AD7816 devices")
> Cc: stable@vger.kernel.org
> Signed-off-by: Gabriel Shahrouzi <gshahrouzi@gmail.com>
> ---

LGTM, do you happen to have this device? It would more interesting to move this
driver out of staging :)

Acked-by: Nuno Sá <nuno.sa@analog.com>

> Changes since v3:
> - Tag stable@vger.kernel.org instead of an email CC
> - Use the correct version for patch
> Changes since v2:
> - Add fixes tag that references commit that introduced the bug.
>         - Replace sysfs_streq with strcmp.
> ---
>  drivers/staging/iio/adc/ad7816.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/staging/iio/adc/ad7816.c
> b/drivers/staging/iio/adc/ad7816.c
> index 6c14d7bcdd675..081b17f498638 100644
> --- a/drivers/staging/iio/adc/ad7816.c
> +++ b/drivers/staging/iio/adc/ad7816.c
> @@ -136,7 +136,7 @@ static ssize_t ad7816_store_mode(struct device *dev,
>   struct iio_dev *indio_dev = dev_to_iio_dev(dev);
>   struct ad7816_chip_info *chip = iio_priv(indio_dev);
>
> - if (strcmp(buf, "full")) {
> + if (strcmp(buf, "full") == 0) {
>   gpiod_set_value(chip->rdwr_pin, 1);
>   chip->mode = AD7816_FULL;
>   } else {