[PATCH v3 2/4] iio: health: max30100: do not use internal iio_dev lock

[Andy Shevchenko]

On Wed, Oct 12, 2022 at 6:15 PM Nuno Sá <nuno.sa at analog.com> wrote:
>
> The pattern used in this device does not quite fit in the
> iio_device_claim_direct_mode() typical usage. In this case,
> iio_buffer_enabled() was being used not to prevent the raw access but to
> allow it. Hence, let's make use of the new
> iio_device_claim_buffer_mode() API to make sure we stay in buffered mode
> during the complete read.
>
> Note that we are shadowing the error code returned by
> iio_device_claim_buffer_mode() so that we keep the original one
> (-EAGAIN). The reason is that some userspace stack might already be
> relying on this particular code so that we are not taking chances and
> leave it alone.

The above line widths seem a bit arbitrary to me. But I think it's due
to function names in them.
Perhaps you can make them less deviated by shuffling a bit, like
moving "but to" to the next line.

> Signed-off-by: Nuno Sá <nuno.sa at analog.com>
> ---
>  drivers/iio/health/max30100.c | 9 +++------
>  1 file changed, 3 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/iio/health/max30100.c b/drivers/iio/health/max30100.c
> index 2cca5e0519f8..6ac49901c9da 100644
> --- a/drivers/iio/health/max30100.c
> +++ b/drivers/iio/health/max30100.c
> @@ -387,18 +387,15 @@ static int max30100_read_raw(struct iio_dev *indio_dev,
>                  * Temperature reading can only be acquired while engine
>                  * is running
>                  */
> -               mutex_lock(&indio_dev->mlock);
> -
> -               if (!iio_buffer_enabled(indio_dev))

> +               if (iio_device_claim_buffer_mode(indio_dev)) {

I think a summary of replacing error code is good to have here, like

/*
 * Replacing -EBUSY or other error code
 * returned by iio_device_claim_buffer_mode()
 * because user space may rely on the current
 * one.
 */

>                         ret = -EAGAIN;
> -               else {
> +               } else {
>                         ret = max30100_get_temp(data, val);
>                         if (!ret)
>                                 ret = IIO_VAL_INT;
>
> +                       iio_device_release_buffer_mode(indio_dev);
>                 }
> -
> -               mutex_unlock(&indio_dev->mlock);
>                 break;
>         case IIO_CHAN_INFO_SCALE:
>                 *val = 1;  /* 0.0625 */

-- 
With Best Regards,
Andy Shevchenko