[mythtv-users] Permission problem on /dev/video 0-3

mythtv.t.wuuza at xoxy.net mythtv.t.wuuza at xoxy.net
Thu Jul 29 15:44:31 UTC 2010

> The udev rules made it: 
> crw-rw-rw- root video 
> But again non of this fixes mythbackend running correctly on bootup. I 
> to VNC/SSH in and restart the backend, but once I do it works fine. 

I started having a similar problem a couple of days ago after getting 
kernel and myth updates among others, using Mythbuntu 10.04 with 
autobuilds.  I have not noticed the problem on boot but rather on resuming 
from suspend.  I already had a pm-suspend script that runs on resume to 
make sure myth works, so I added some logging to see what was going on 
with /dev/video*.  Apparently something changed in the timing because 
/dev/video1 (I force start at 1) for my PVR150 is owned root:root at 
first, and only after a few seconds (anywhere from 2-6) does udev change 
the ownership to root:video with rw for the group.  I have ivtv in the 
list of modules for pm-suspend to unload/reload, which is presumably why 
/dev/video* needs to be set up on resume, but I'm not sure what other 
parts changed that affected the timing.  In my resume script I am forced 
to bounce the backend anyway because of firewire capture, so my fix was to 
loop until the video group appears on /dev/video1 before restarting the 
backend, enabling the backend sees the input with the correct permissions. 


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