diff mbox series

[v1,04/15] iio: adc: ad7768-1: Fix conversion result sign

Message ID e521bb5cb60d413edbcd1ea582fd81073218eaf5.1736201898.git.Jonathan.Santos@analog.com (mailing list archive)
State New
Headers show
Series iio: adc: ad7768-1: Add features, improvements, and fixes | expand

Commit Message

Jonathan Santos Jan. 7, 2025, 3:25 p.m. UTC 
From: Sergiu Cuciurean <sergiu.cuciurean@analog.com>

The ad7768-1 is a fully differential ADC, 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")
Signed-off-by: Sergiu Cuciurean <sergiu.cuciurean@analog.com>
---
 drivers/iio/adc/ad7768-1.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Comments

David Lechner Jan. 7, 2025, 11:39 p.m. UTC | #1 
On 1/7/25 9:25 AM, Jonathan Santos wrote:
> From: Sergiu Cuciurean <sergiu.cuciurean@analog.com>
> 
> The ad7768-1 is a fully differential ADC, 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")
> Signed-off-by: Sergiu Cuciurean <sergiu.cuciurean@analog.com>
> ---
Reviewed-by: David Lechner <dlechner@baylibre.com>
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)