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ianux

Member

From: France

Registered: 2008-12-02

Posts: 16

No more /dev/video0, no webcam

Hi archers,

I have a builtin USB webcam on my laptop that works with the uvcvideo module.

Something like 6 month ago everything was fine, /dev/video0 was present and I was able to fire up my webcam with mplayer tv:// or cheese.

But then, it began to flicker, i.e /dev/video0 was present on boot and after a moment it disappeared and then reappeared and so on. Kernel logs show that the webcam was regularly re-detected.

But recently, it wasn't even detected on boot, therefore the uvcvideo module is not loaded anymore. Modprobeing it changes nothing.

I wonder if this related to the kernel (I use both core repo kernel and repo-ck one) or some trouble with udev. There is no trace of webcam in dmesg. lsusb neither list it.

What's wrong ?

cfr

Member

From: Cymru

Registered: 2011-11-27

Posts: 7,178

Re: No more /dev/video0, no webcam

Have you ruled out hardware?

Does journalctl mention it? (e.g. grep uvc)

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ianux

Member

From: France

Registered: 2008-12-02

Posts: 16

Re: No more /dev/video0, no webcam

Have you ruled out hardware?

Does journalctl mention it? (e.g. grep uvc)

I use rsyslog with journald, so I greped uvc in /var/log/everything.log

I found

Dec 24 17:16:33 localhost kernel: uvcvideo: Found UVC 1.00 device USB 2.0 Camera (04f2:b013)
Dec 24 17:16:33 localhost kernel: usbcore: registered new interface driver uvcvideo
Dec 25 00:45:05 localhost kernel: uvcvideo: Found UVC 1.00 device USB 2.0 Camera (04f2:b013)
Dec 25 09:49:34 localhost kernel: uvcvideo: Found UVC 1.00 device USB 2.0 Camera (04f2:b013)
Dec 25 10:05:42 localhost kernel: uvcvideo: Found UVC 1.00 device USB 2.0 Camera (04f2:b013)
Dec 25 11:43:17 localhost kernel: uvcvideo: Found UVC 1.00 device USB 2.0 Camera (04f2:b013)
Dec 25 12:20:14 localhost kernel: uvcvideo: Found UVC 1.00 device USB 2.0 Camera (04f2:b013)
Dec 25 13:22:42 localhost kernel: uvcvideo: Found UVC 1.00 device USB 2.0 Camera (04f2:b013)
Dec 25 13:36:31 localhost kernel: uvcvideo: Found UVC 1.00 device USB 2.0 Camera (04f2:b013)

So I looked at /dev and found /dev/video0 ! I have not rebooted since I opened this thread.

So it's not a hardware problem, and the behavior is the same as previously : the webcam come and go randomly (and according to Murphy's law, it goes off when I need it). Maybe it has to do with USB power saving, I don't know.