Re: [PATCH] iio: accel: sca3000: Use sign_extend32() instead of opencoding sign extension.

[Jonathan Cameron <jic23@kernel.org>]

On Thu,  3 Jun 2021 17:47:29 +0100
Jonathan Cameron <jic23@kernel.org> wrote:

> From: Jonathan Cameron <Jonathan.Cameron@huawei.com>
> 
> Whilst nice to get rid of this non obvious code, this also clears a
> static checker warning:
> 
> drivers/iio/accel/sca3000.c:734 sca3000_read_raw()
> warn: no-op. '((*val) << 19) >> 19'
> 
> Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
> Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

If someone could give this a quick sanity check that would be great.

Thanks,

Jonathan

> ---
>  drivers/iio/accel/sca3000.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/drivers/iio/accel/sca3000.c b/drivers/iio/accel/sca3000.c
> index cb753a43533c..0692ccb80293 100644
> --- a/drivers/iio/accel/sca3000.c
> +++ b/drivers/iio/accel/sca3000.c
> @@ -731,8 +731,7 @@ static int sca3000_read_raw(struct iio_dev *indio_dev,
>  				return ret;
>  			}
>  			*val = (be16_to_cpup((__be16 *)st->rx) >> 3) & 0x1FFF;
> -			*val = ((*val) << (sizeof(*val) * 8 - 13)) >>
> -				(sizeof(*val) * 8 - 13);
> +			*val = sign_extend32(*val, 13);
>  		} else {
>  			/* get the temperature when available */
>  			ret = sca3000_read_data_short(st,