[Bug 2151784] Re: No ALS (ambient light sensor) exposed on ThinkPad T14s Gen 6 – Chicony 04F2:B83F HID sensor hub only provides proximity IIO devices

** Tags added: kernel-daily-bug -- You received this bug notification because you are subscribed to linux in Ubuntu. Matching subscriptions: Bgg, Bmail, Nb 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 Status in linux package in Ubuntu: New Bug description: 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. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2151784/+subscriptions