Public bug reported:
On a Lenovo ThinkPad T14s Gen 6, the integrated camera module (Chicony
04F2:B83F) exposes a HID sensor hub that creates two IIO devices, but
both appear to be proximity sensors only. No ambient light sensor (ALS)
/ illuminance channels are exposed to userspace, so desktop
auto‑brightness cannot work.
This looks similar to other cases where a combined proximity + ALS HID
sensor is only partially supported by the HID/IIO stack.
System information:
Hardware: Lenovo ThinkPad T14s Gen 6
OS: Ubuntu 26.04 LTS (“resolute”)
Kernel:
Linux Laptopx 7.0.0-15-generic #15-Ubuntu SMP PREEMPT_DYNAMIC Wed
Apr 22 16:06:43 UTC 2026 x86_64 GNU/Linux
(If you file with ubuntu-bug linux, this will be collected
automatically.)
Observed behavior:
The integrated camera is detected as:
Chicony Electronics Co.,Ltd. Integrated Camera (04F2:B83F)
hid-sensor-hub 0003:04F2:B83F.0001
HID-SENSOR-200011.2.auto -> iio:device0
HID-SENSOR-200011.4.auto -> iio:device1
Relevant dmesg lines:
hid: raw HID events driver (C) Jiri Kosina
usbcore: registered new interface driver usbhid
usbhid: USB HID core driver
hid-generic 0003:04F2:B83F.0001: hiddev0,hidraw0: USB HID v1.11 Device
[Chicony Electronics Co.,Ltd. Integrated Camera] on usb-0000:00:14.0-4/input4
hid-sensor-hub 0003:04F2:B83F.0001: hiddev0,hidraw0: USB HID v1.11 Device
[Chicony Electronics Co.,Ltd. Integrated Camera] on usb-0000:00:14.0-4/input4
input: Intel HID events as /devices/platform/INTC107B:00/input/input12
hid-sensor-hub 0003:04F2:B83F.0001: No report with id 0xffffffff found
hid-sensor-hub 0003:04F2:B83F.0001: No report with id 0xffffffff found
hid-sensor-hub 0003:04F2:B83F.0001: No report with id 0xffffffff found
udevadm info -a /sys/bus/iio/devices/iio:device0 (excerpt):
looking at device
'/devices/pci0000:00/0000:00:14.0/usb3/3-4/3-4:1.4/0003:04F2:B83F.0001/HID-SENSOR-200011.2.auto/iio:device0':
KERNEL=="iio:device0"
SUBSYSTEM=="iio"
DRIVER==""
ATTR{buffer/data_available}=="0"
ATTR{buffer/direction}=="in"
ATTR{buffer/enable}=="0"
ATTR{buffer/length}=="2"
ATTR{buffer/watermark}=="1"
ATTR{buffer0/data_available}=="0"
ATTR{buffer0/direction}=="in"
ATTR{buffer0/enable}=="0"
ATTR{buffer0/in_attention_en}=="0"
ATTR{buffer0/in_attention_index}=="2"
ATTR{buffer0/in_attention_type}=="le:s8/32>>0"
ATTR{buffer0/in_proximity0_en}=="0"
ATTR{buffer0/in_proximity0_index}=="0"
ATTR{buffer0/in_proximity0_type}=="le:s8/32>>0"
ATTR{buffer0/in_proximity1_en}=="0"
ATTR{buffer0/in_proximity1_index}=="1"
udevadm info -a /sys/bus/iio/devices/iio:device1 (excerpt):
looking at device
'/devices/pci0000:00/0000:00:14.0/usb3/3-4/3-4:1.4/0003:04F2:B83F.0001/HID-SENSOR-200011.4.auto/iio:device1':
KERNEL=="iio:device1"
SUBSYSTEM=="iio"
DRIVER==""
ATTR{buffer/data_available}=="0"
ATTR{buffer/direction}=="in"
ATTR{buffer/enable}=="0"
ATTR{buffer/length}=="2"
ATTR{buffer/watermark}=="1"
ATTR{buffer0/data_available}=="0"
ATTR{buffer0/direction}=="in"
ATTR{buffer0/enable}=="0"
ATTR{buffer0/in_attention_en}=="0"
ATTR{buffer0/in_attention_index}=="2"
ATTR{buffer0/in_attention_type}=="le:s16/32>>0"
ATTR{buffer0/in_proximity0_en}=="0"
ATTR{buffer0/in_proximity0_index}=="0"
ATTR{buffer0/in_proximity0_type}=="le:s16/32>>0"
ATTR{buffer0/in_proximity1_en}=="0"
ATTR{buffer0/in_proximity1_index}=="1"
Under /sys/bus/iio/devices/iio:device* there are only
proximity‑related attributes (in_proximity*, in_attention*). There are
no ALS‑related attributes such as in_illuminance*, in_lux*, or anything
with light / als in the name.
As a result:
iio-sensor-proxy does not expose any ALS to userspace.
GNOME/KDE auto‑brightness cannot function.
There is no ALS data available for user scripts either.
Expected behavior:
If the camera module / HID sensor hub includes an ALS (which is typical
for modern laptop camera modules), I would expect:
The HID sensor hub driver and related hid_sensor_* drivers to expose an IIO
device with ALS channels (e.g. in_illuminance_raw, in_illuminance_scale, etc.),
or
A clear indication that the hardware does not provide ALS at all.
Right now, only proximity sensors are visible, and ALS (if present) is
not exposed.
Steps to reproduce:
Boot Ubuntu 26.04 on a Lenovo ThinkPad T14s Gen 6.
Run:
uname -a
lsb_release -a
dmesg | egrep -i 'hid|sensor|iio'
ls /sys/bus/iio/devices
ls -R /sys/bus/iio/devices/iio:device*
Observe that:
Only HID-SENSOR-200011.* devices exist for the Chicony 04F2:B83F camera.
IIO attributes are limited to proximity / attention; no ALS /
illuminance attributes are present.
Impact:
Users of this ThinkPad model on Ubuntu cannot use automatic screen
brightness based on ambient light.
Desktop environments relying on iio-sensor-proxy see no ALS, reducing
usability and power efficiency.
Test case:
On a ThinkPad T14s Gen 6, install Ubuntu 26.04 with the stock
linux-image-generic kernel.
Log in to a GNOME session.
Check:
monitor-sensor output (from iio-sensor-proxy).
Contents of /sys/bus/iio/devices/iio:device*.
Confirm that:
No ALS / illuminance readings are available.
Only proximity‑related attributes exist.
Regression potential:
A fix would likely involve adding or adjusting HID/IIO support for the
Chicony 04F2:B83F sensor hub.
Main regression risk: mis‑interpreting HID descriptors and affecting other
devices using the same HID sensor ID.
Careful matching on USB VID:PID and/or HID usage pages/IDs should limit the
change to this hardware.
Additional information / willingness to help:
I can provide on request:
lsusb -v -d 04f2:b83f
Raw HID reports (e.g. from hid-recorder on /dev/hidraw0)
Full udevadm info output for the HID and IIO devices
I am also happy if this bug is forwarded upstream to the Linux kernel
HID/IIO maintainers.
Thank you for looking into this.
** Affects: linux (Ubuntu)
Importance: Undecided
Status: New
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https://bugs.launchpad.net/bugs/2151784
Title:
No ALS (ambient light sensor) exposed on ThinkPad T14s Gen 6 – Chicony
04F2:B83F HID sensor hub only provides proximity IIO devices
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