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

Gabriel Shahrouzi
2025-04-15T13:54:22Z

On Tue, Apr 15, 2025 at 5:13 AM Nuno Sá <noname.nuno@gmail.com> wrote:
>
> 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 :)
Unfortunately, I do not have this device. However, I would still be
interested in contributing if possible. I was looking over
https://lore.kernel.org/all/20230716144024.30ded663@jic23-huawei/T/
where the goal seemed to be to modernize it by replacing the sysfs
interface with the iio channel. I also looked through the datasheet
and it seemed to be missing some stuff like a channel that can be
selected.
>
> 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 {