## What's been ruled out - USB autosuspend (device was suspending; disabling via udev `power/control=on` fixed an earlier separate symptom — the browser's "camera not found" error disappeared once the device reliably stays powered — but did not fix frame delivery) - `uvcvideo quirks=128` (UVC_QUIRK_FIX_BANDWIDTH) — no effect - `power_line_frequency` control (known bug class on other Lenovo-integrated cameras, see kernel patch "media: uvcvideo: Fix power line control for Lenovo Integrated Camera" for Shine-Optics 3277:009e) — set explicitly via v4l2-ctl, no effect - Lenovo EC camera-power gate (`/sys/devices/pci0000:00/0000:00:1f.0/PNP0C09:00/VPC2004:00/camera_power`) — toggled off/on, no effect, reads `1` (enabled) - No physical privacy shutter on this model; no dedicated Fn camera-toggle hotkey found - No pending firmware updates for "Integrated Camera" via fwupd/LVFS - Fresh `modprobe -r uvcvideo && modprobe uvcvideo` before each test to rule out stale driver state - GNOME camera privacy toggle off (not blocking), correct udev ACL for /dev/video0, no other process holding the device open, no `/etc/modprobe.d` blacklist affecting uvcvideo/i2c_hid/psmouse - **Kernel version 6.8.0-137-generic vs 6.14.0-37-generic — identical failure on both**, ruling out a kernel-version-specific regression within 24.04's supported kernels - IPU6 kernel modules present vs absent — no observed difference in UVC camera behavior either way
## Working theory The three vendor Extension Units suggest the OEM Windows driver performs a proprietary init/wake sequence on the sensor via one of these XUs before it will actually output pixel data. `uvcvideo`'s generic UVC negotiation (probe/commit/altsetting) succeeds because that part of the protocol is standard, but without the correct XU command sequence the sensor silently stays in a "streaming but dark" state — it acknowledges the stream request and sends header-only payloads, but never activates actual pixel readout. Since this camera reportedly worked under this same laptop on Ubuntu 22.04, and both 24.04-available kernels (6.8 and 6.14) show the identical failure, something changed between the 22.04-era kernel/driver/quirk table and 24.04's — a bisect against the actual 22.04 kernel version (if still available, or via a live-USB test) would help narrow this down further, as would confirming whether an older `uvcvideo` quirk table entry for this VID:PID existed and was later removed/changed upstream. ## Requested - Guidance on whether a uvcvideo quirk/XU-init patch is feasible for this device, similar to the existing "Fix power line control for Lenovo Integrated Camera" precedent - Any pointers to existing bug reports for Chicony 04f2:b6cb or Lenovo model 82NC camera issues - Confirmation of which kernel/uvcvideo version 22.04 shipped for this hardware and what, if anything, that version does differently for this device's XU init -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/2163506 Title: Integrated webcam (Chicony 04f2:b6cb) on Lenovo Yoga Slim 7 Pro 14IHU5 (model 82NC) doesnt work after upgrading to Ubuntu 24.04 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2163506/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
