Re: [PATCH v2 01/16] iio: adc: ad7768-1: Fix conversion result sign

[Jonathan Cameron <jic23@kernel.org>]

On Mon, 27 Jan 2025 12:11:01 -0300
Jonathan Santos <Jonathan.Santos@analog.com> wrote:

> From: Sergiu Cuciurean <sergiu.cuciurean@analog.com>
> 
> The ad7768-1 ADC output code is two's complement, meaning that the voltage
> conversion result is a signed value.. Since the value is a 24 bit one,
> stored in a 32 bit variable, the sign should be extended in order to get
> the correct representation.
> 
> Also the channel description has been updated to signed representation,
> to match the ADC specifications.
> 
> Fixes: a5f8c7da3dbe ("iio: adc: Add AD7768-1 ADC basic support")
> Reviewed-by: David Lechner <dlechner@baylibre.com>
> Reviewed-by: Marcelo Schmitt <marcelo.schmitt@analog.com>
> Signed-off-by: Sergiu Cuciurean <sergiu.cuciurean@analog.com>
> ---
> v2 Changes:
> * Patch moved to the start of the patch series.
Applied to the fixes-togreg branch of iio.git.

Thanks,

Jonathan

> ---
>  drivers/iio/adc/ad7768-1.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/iio/adc/ad7768-1.c b/drivers/iio/adc/ad7768-1.c
> index 113703fb7245..c3cf04311c40 100644
> --- a/drivers/iio/adc/ad7768-1.c
> +++ b/drivers/iio/adc/ad7768-1.c
> @@ -142,7 +142,7 @@ static const struct iio_chan_spec ad7768_channels[] = {
>  		.channel = 0,
>  		.scan_index = 0,
>  		.scan_type = {
> -			.sign = 'u',
> +			.sign = 's',
>  			.realbits = 24,
>  			.storagebits = 32,
>  			.shift = 8,
> @@ -371,7 +371,7 @@ static int ad7768_read_raw(struct iio_dev *indio_dev,
>  
>  		ret = ad7768_scan_direct(indio_dev);
>  		if (ret >= 0)
> -			*val = ret;
> +			*val = sign_extend32(ret, chan->scan_type.realbits - 1);
>  
>  		iio_device_release_direct_mode(indio_dev);
>  		if (ret < 0)