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I have an old-ish System76 galago pro (galp3). Until today my webcam was working fine.

I just upgraded it to 22.04 (from 20.04). The machine boots fine and the login screen with 3 users shows up. Within a second or two, the webcam active light comes on and stays on.

Cheese doesn't work, it says "There was an error playing video from the webcam".

Some debugging info:

$ journalctl -b | grep -i bison
Aug 11 16:55:12 compy386 kernel: usb 1-7: Product: BisonCam, NB Pro
Aug 11 16:55:13 compy386 kernel: usb 1-7: Found UVC 1.00 device BisonCam, NB Pro (5986:2112)
Aug 11 16:55:13 compy386 kernel: input: BisonCam, NB Pro: BisonCam, NB  as /devices/pci0000:00/0000:00:14.0/usb1/1-7/1-7:1.0/input/input22

$ lsusb  | grep Bison
Bus 001 Device 002: ID 5986:2112 Acer, Inc BisonCam, NB Pro


$ cheese
Aug 11 17:03:40 compy386 cheese[5341]: Device '/dev/video0' is busy: ../sys/v4l2/gstv4l2object.c(4033): gst_v4l2_object_set_format_full (): /GstCameraBin:camerabin/GstWrapperCameraBinSrc:camera_source/GstBin:bin18/GstV4l2Src:v4l2src1:
Call to S_FMT failed for MJPG @ 1280x720: Device or resource busy


$ uname -a
Linux foghorn 5.18.10-76051810-generic #202207071639~1657252310~20.04~7d5e891~dev-Ubuntu SMP PREEMPT_DY x86_64 x86_64 x86_64 GNU/Linux


$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 22.04.1 LTS
Release:    22.04
Codename:   jammy

Any ideas?

Adam Monsen
  • 2,225

1 Answers1

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Ah, it was motion! I contacted System76 support and they suggested using fuser like so:

$ sudo fuser -v /dev/video*
                     USER        PID ACCESS COMMAND
/dev/video0:         motion     7943 F...m motion

I forgot I was tinkering with motion a while back. Maybe something during the upgrade changed motion to start automatically.

Thank you Matt at System76! Fixed with

sudo systemctl stop motion
sudo apt autoremove --purge motion

Now the webcam active light is usually off except when I use something like cheese.

Note that lsmod | egrep '^Module|uvcvideo' was also helpful (thanks again, Matt!) to see that 1 thing is using the USB webcam while motion or cheese is running, and 0 things when they are not.

Adam Monsen
  • 2,225