FAILED: patch "[PATCH] iio: adc: max1363: sign-extend bipolar differential channel" failed to apply to 5.10-stable tree

The patch below does not apply to the 5.10-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 <[email protected]>.

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-5.10.y
git checkout FETCH_HEAD
git cherry-pick -x 91908c0a78baddc8572aa3ab69e62ee2eb496ba4
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2026100625-reverse-alabaster-6736@gregkh' --subject-prefix 'PATCH 5.10.y' 'HEAD^..'

Possible dependencies:

thanks,

greg k-h

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

From 91908c0a78baddc8572aa3ab69e62ee2eb496ba4 Mon Sep 17 00:00:00 2001
From: Cong Nguyen <[email protected]>
Date: Mon, 10 Aug 2026 23:44:46 +0700
Subject: [PATCH] iio: adc: max1363: sign-extend bipolar differential channel
reads

MAX1363 differential channels are bipolar, but max1363_read_single_chan() masks the raw value to the ADC resolution without sign-extending it. Negative differential readings are therefore reported to userspace as large positive values (e.g. -1 as 4095 on a 12-bit part).

Sign-extend the masked value from the resolution bit for differential channels. Single-ended channels are unipolar and are left unchanged.

index 65a2d92bb112..629c53af6472 100644
@@ -404,6 +404,14 @@ static int max1363_read_single_chan(struct iio_dev *indio_dev,
 
 		data = rxbuf[0];
 	}
+
+	/*
+	 * Differential channels are bipolar and the device returns the sample
+	 * in two's complement, so sign-extend it from the resolution bit.
+	 */
+	if (chan->differential)
+		data = sign_extend32(data, st->chip_info->bits - 1);
+
 	*val = data;
 
 	return 0;

From: Cong Nguyen <[email protected]>

[ Upstream commit 91908c0a78baddc8572aa3ab69e62ee2eb496ba4 ]

MAX1363 differential channels are bipolar, but max1363_read_single_chan() masks the raw value to the ADC resolution without sign-extending it. Negative differential readings are therefore reported to userspace as large positive values (e.g. -1 as 4095 on a 12-bit part).

Sign-extend the masked value from the resolution bit for differential channels. Single-ended channels are unipolar and are left unchanged.

---
 drivers/iio/adc/max1363.c | 8 ++++++++
 1 file changed, 8 insertions(+)

index 29c1824162cd0..c427fdf93dcbd 100644
@@ -409,6 +409,14 @@ static int max1363_read_single_chan(struct iio_dev *indio_dev,
 		}
 		data = rxbuf[0];
 	}
+
+	/*
+	 * Differential channels are bipolar and the device returns the sample
+	 * in two's complement, so sign-extend it from the resolution bit.
+	 */
+	if (chan->differential)
+		data = sign_extend32(data, st->chip_info->bits - 1);
+
 	*val = data;
 
 error_ret:

2.53.0