## Summary
Integrated webcam (Chicony 04f2:b6cb) on Lenovo Yoga Slim 7 Pro 14IHU5 (model
82NC) enumerates correctly, negotiates UVC formats, and streams isochronous
packets with zero USB errors — but every video payload contains only the
12-byte UVC stream header and **no pixel data**. Camera indicator LED turns on,
ealthy, but no application (ffmpeg, v4l2-ctl rawstream capture, Chrome/Google
Meet, Zoom) ever receives a usable frame. This is a regression: the camera
worked normally undeUbuntu 22.04 on this same machine, before upgradin
## System
- Laptop: Lenovo Yoga Slim 7 Pro 14IHU5, system model 82NC, BIOS FJCN69WW
- OS: Ubuntu 24.04.4 LTS
(previously worked fine o)
- Kernels tested: 6.8.0-137-generic (GA) and 6.14.0-37-generic (HWE) —
**identical failure on both**, confirmed with matched usbmon captures on each
(see below). This rules ouegression between 6.8 and 6.14; the break
happenedsomewhere between 22.04's kernel/driver stack and 24.04's.
- Camera: Chicony Electronics Integrated Camera, U bcdDevice 80.18
- Composite device: RGB sensor on interface 0/1 (UVC 1.10, /dev/video0-1),
separate IR sensor on interface 2/3 (UVC 1.50, /dev/video2-3, used for Windows
Hello / face auth format-negotiation failure, not the focus of thisreport)
- Camera exposes 3 vendor Extension Units (XUs) r, which are typically used
by the OEM Windowsdriver to perform proprietary sensor init:
- XU 4: guid {1229a78c-47b4-4094-b0ce-db07386f
- XU 7: guid {26b8105a-0713-4870-979d-da79444bb68e}
- XU 8: guid
{0f3f95dc-2632-4c4e-92c9-a04782f4
## Possible IPU6 connection
This machine also has an Intel IPU6 MIPI camera stack path available
(`linux-modules-ipu6-generic-hwe-24.04` /
`linux-modules-ipu6-6.14.0-37-generic` packages exring earlier troubleshooting
the reporter installed and then removed/purged these IPU6 packages, without
effect on the UVC camera's frame delivery either way (tested with them absent).
It's possible the working 22.04 setup relr-init path (or an older `uvcvideo`
with adevice-specific quirk/XU sequence) that isn't present in 24.04's stack —
worth checking whether
`linux-modules-ipu6-generic-hwe-24.04` (properly is the behavior, though it was
not observed to helpin this case.
Separately, and not the cause of the camera bug itself: removing the IPU6
packages had an unrelated destructive side effect —
`linux-modules-extra-6.14.0-37-generic` (containinGPU/other drivers) was left
uninstalled, breakingWiFi, touchpad, and display scaling specifically on 6.14
until reinstalled. That has been resolved and is mentioned only for
completeness/context.
## Steps to reproduce
v4l2-ctl -d /dev/video0 --set-fmt-video=width=640,height=480,pixelformat=YUYV
--stream-mmap --stream-count=5
--stream-to=/tmp/
Result: hangs until interrupted; output file is 0 bytes. Same result via
`ffmpeg -f v4l2 -i /dev/video0 ...` (both `mjpeg` and `yuyv422` input formats):
ffmpeg opens the device,iption, but gets EOF with no decodable frame.Identical
result on both 6.8.0-137-generic and 6.14.0-37-generic.
## Evidence: usbmon capture during a stream attempt
Captured via
`/sys/kernel/debug/usb/usbmon/3u` whioth kernels. USB control-plane traffic
(formatprobe/commit, altsetting select) completes normally. Isochronous IN
completions on endpoint 1 look like this, repeated for theentire capture with
no errors, on **both** kernel
C Zi:3:002:1 0:1:15352:0 32 0:0:12 0:2940:12 0:5880:12 0:8820:12 0:11760:12
94080 = 0c8c0000 000075c3 9f017d07 00000000... Every isochronous packet
descriptor completes withual_length=12 bytes** — exactly the size of a bareUVC
payload header (FID/EOF/PTS/SCR fields) with zero image bytes following it.
This pattern is consistent across hundreds of isochronous packets captured on
each kernel; no URcol errors anywhere in dmesg on either kernel.
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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
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