[PATCH v8 5/5] iio: ABI: Encourage differential voltage ABI usage

From: Marcelo Schmitt

Date: Thu Jul 23 2026 - 15:57:33 EST


So far, parts that could only do differential voltage measurements were
only required to have a consistent labeling of their channels by complying
either to voltageY or to voltageY-voltageZ ABI. Over time, code maintainers
came to the conclusion that the voltageY-voltageZ ABI is better suited for
differential-only chips as it provides a simple indication to users that
the channels measure the difference of two inputs.

Adjust the ABI documentation to recommend using the voltageY-voltageZ ABI
for chips that do only differential voltage measurements.

Signed-off-by: Marcelo Schmitt <marcelo.schmitt@xxxxxxxxxx>
---
New patch in v8.

The updated ABI doc might not have gotten very clear, so I'm completely fine
with any modifications to this patch. Also, since the documentation update is
minimal, doesn't add any new ABI, and might be picked up through Jonathan's
tree, I'm not CCing the documentaion mailing list.

Documentation/ABI/testing/sysfs-bus-iio | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/Documentation/ABI/testing/sysfs-bus-iio b/Documentation/ABI/testing/sysfs-bus-iio
index 5cc2e82c4997..7446e07b9ab2 100644
--- a/Documentation/ABI/testing/sysfs-bus-iio
+++ b/Documentation/ABI/testing/sysfs-bus-iio
@@ -162,10 +162,11 @@ Contact: linux-iio@xxxxxxxxxxxxxxx
Description:
Raw (unscaled) differential voltage measurement equivalent to
channel Y - channel Z where these channel numbers apply to the
- physically equivalent inputs when non differential readings are
- separately available. In differential only parts, then all that
- is required is a consistent labeling. Units after application
- of scale and offset are millivolts.
+ physically equivalent inputs when non-differential readings are
+ separately available. Even though differential-only parts had
+ been merely required to have consistent channel labeling, this
+ ABI is preferred over the non-differential one for those chips.
+ Units after application of scale and offset are millivolts.

What: /sys/bus/iio/devices/iio:deviceX/in_altvoltageY_rms_raw
KernelVersion: 6.18
--
2.53.0