FAILED: patch "[PATCH] iio: adc: ad7768-1: Fix conversion result sign" failed to apply to 5.15-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 5.15-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y
git checkout FETCH_HEAD
git cherry-pick -x 8236644f5ecb180e80ad92d691c22bc509b747bb
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2025041759-mumbling-moonlike-a1a0@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^..

Possible dependencies:



thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 8236644f5ecb180e80ad92d691c22bc509b747bb Mon Sep 17 00:00:00 2001
From: Sergiu Cuciurean <sergiu.cuciurean@analog.com>
Date: Thu, 6 Mar 2025 18:00:29 -0300
Subject: [PATCH] iio: adc: ad7768-1: Fix conversion result sign

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>
Signed-off-by: Jonathan Santos <Jonathan.Santos@analog.com>
Cc: <Stable@vger.kernel.org>
Link: https://patch.msgid.link/505994d3b71c2aa38ba714d909a68e021f12124c.1741268122.git.Jonathan.Santos@analog.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

diff --git a/drivers/iio/adc/ad7768-1.c b/drivers/iio/adc/ad7768-1.c
index ea829c51e80b..09e7cccfd51c 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,
@@ -373,7 +373,7 @@ static int ad7768_read_raw(struct iio_dev *indio_dev,
 		iio_device_release_direct(indio_dev);
 		if (ret < 0)
 			return ret;
-		*val = ret;
+		*val = sign_extend32(ret, chan->scan_type.realbits - 1);
 
 		return IIO_VAL_INT;