Re: [Bug 219890] New: illuminance sensor is jittering between correct value and 0.03lux

[Jonathan Cameron <jic23@kernel.org>]

On Mon, 17 Mar 2025 09:38:50 +0000
bugzilla-daemon@kernel.org wrote:

> https://bugzilla.kernel.org/show_bug.cgi?id=219890
> 
>             Bug ID: 219890
>            Summary: illuminance sensor is jittering between correct value
>                     and 0.03lux
>            Product: Drivers
>            Version: 2.5
>           Hardware: All
>                 OS: Linux
>             Status: NEW
>           Severity: normal
>           Priority: P3
>          Component: IIO
>           Assignee: drivers_iio@kernel-bugs.kernel.org
>           Reporter: wysiwyg81@rbox.co
>         Regression: No
> 
> Hello,
> 
> I have a Lenovo thinkbook 13x gen4.
> Automatic brightness control is flickering in Gnome, so I checked sensor with
> monitor-sensor command (iio-sensor-proxy).
> 
> it shows following behavior:
> monitor-sensor  --light
>     Waiting for iio-sensor-proxy to appear
> +++ iio-sensor-proxy appeared
> === Has ambient light sensor (value: 316,000000, unit: lux)
>     Light changed: 299,000000 (lux)
>     Light changed: 0,030000 (lux)
>     Light changed: 299,000000 (lux)
>     Light changed: 0,030000 (lux)
>     Light changed: 299,000000 (lux)
>     Light changed: 0,030000 (lux)
>     Light changed: 305,000000 (lux)
> 
> 
> the 0.03 is unexpected has it has never been that dark.
> it seems it's not a iio-sensor-proxy bug as I can see similar behavior by
> checking directly content of here :
> /sys/bus/iio/devices/iio:device0/in_illuminance_raw
> 
> 
> I checked the behavior on windows to make sure it's not an hardware failure
> from my sensor.
> While I cannot have direct access to raw sensor data on windows, the automatic
> brightness is perfectly smooth: no flickering of any kind.
> 
> I didn't found sensor name:
> ❯ cat  /sys/bus/iio/devices/iio:device0/name
> als

Two possibles types. It's either a hid sensor or an ACPI class interface
with a sensor wrapped up in firmware.

My guess is hid-sensor.  Can you do an
ls -lh in /sys/iio/devices/
so we can see what the parent is.
+CC Srinivas based on playing guess the sensor.

Jonathan





> 
> But if there is other place I could look, let me know.
>