Arch Linux

dawid.loubser

Member

Registered: 2012-08-09

Posts: 23

[Solved] Webcam(s) disappeared on Dell XPS (Precision 5530)

Hi, on a Dell Precision 5530 (same as XPS 9570) all webcams - wether built-in, or plugging in an external USB Logitech webcam - have disappeared from all the apps that I used to use them from.
This includes Firefox, Zoom (AUR) or even qv4l2.

DMESG outputs this:

$ dmesg | grep -i video
[    0.779681] ACPI: Added _OSI(Linux-Dell-Video)
[    1.092315] pci 0000:00:02.0: Video device with shadowed ROM at [mem 0x000c0000-0x000dffff]
[   36.278031] ACPI: Video Device [GFX0] (multi-head: yes  rom: no  post: no)
[   36.357360] input: Video Bus as /devices/LNXSYSTM:00/LNXSYBUS:00/PNP0A08:00/LNXVIDEO:00/input/input11
[   36.360751] ACPI: Video Device [PEGP] (multi-head: no  rom: yes  post: no)
[   36.360884] input: Video Bus as /devices/LNXSYSTM:00/LNXSYBUS:00/PNP0A08:00/device:0b/LNXVIDEO:01/input/input12

How do I debug this issue? I notice these are no longer mounting to /dev/videoX

Thanks!

Solved: The uvcvideo kernel module was accidentally blacklisted by a configuration file sourced elsewhere. Operator error.

Last edited by dawid.loubser (2019-03-22 09:03:33)

dawid.loubser

Member

Registered: 2012-08-09

Posts: 23

Re: [Solved] Webcam(s) disappeared on Dell XPS (Precision 5530)

Update: For some reason, udev is not loading the uvcvideo kernel module automatically.
Running this manually makes my webcam(s) - both internal, and a USB cam, work:

sudo modprobe uvcvideo

Strangely, adding this module to my boot loader's kernel modules command line, or to a file in:

# /etc/modules-load.d/uvcvideo.conf
uvcvideo

does not work. Any theories? This broke soon after the first Linux 5.0 kernel release.

dawid.loubser

Member

Registered: 2012-08-09

Posts: 23

Re: [Solved] Webcam(s) disappeared on Dell XPS (Precision 5530)

I obtained a configuration file to blacklist kernel modules that could turn on the nvidia card in this Optimus laptop. Went back and looked at those, and lo and behold, it was blacklisting uvcvideo in there.
Doh. Removed that line, problem solved.

If anybody has a similar problem, use journalctl to see if the module is blacklisted:

$ journalctl -b | grep uvcvideo