diff mbox series

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

Message ID 64e32c0ac7357ca7ddea813ba932bf957cbbeca2.1737985435.git.Jonathan.Santos@analog.com (mailing list archive)
State Changes Requested
Headers show
Series Add features, improvements, and fixes | expand

Commit Message

Jonathan Santos Jan. 27, 2025, 3:11 p.m. UTC
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.
---
 drivers/iio/adc/ad7768-1.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Comments

Jonathan Cameron Feb. 1, 2025, 3:27 p.m. UTC | #1
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)
Jonathan Cameron Feb. 1, 2025, 3:36 p.m. UTC | #2
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>
Dropped.  Jonathan, this is missing your sign off.

> ---
> v2 Changes:
> * Patch moved to the start of the patch series.
> ---
>  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)
diff mbox series

Patch

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)