[mythtv-users] controlling order of tuner card detection?

R. G. Newbury newbury at mandamus.org
Mon Mar 5 17:44:28 UTC 2007

Anthony Messina wrote:
> On Sun, 2007-03-04 at 14:19 -0500, Michael Thome wrote:
>> Sometimes, my tuner cards are detected and thus assigned to /dev/videoX 
>> numbers in different orders - this wouldn't be an issue except that they 
>> have very different connections and features.  Right now, I've got a 
>> pvr-150 with both cable and video-in and a hd5500 with qam and backup 
>> cable in - if they get detected in the wrong order, /dev/video doesn't 
>> have an mpeg encoder, doesn't have an attached cable box to video0, and 
>> gets darn nasty reception.  I've been planning to replace the 150 with a 
>> 500, but I'm nervous that it'll make things even worse...
>> Is there any way to force detection to proceed in bus-order, presumably 
>> not changing unless I swap cards?
> i have a pvr-350 and a pchdtv-5500 in the same fc6 machine and i've used
> the following in /etc/modprobe.conf in with great success:
> # make hd-5500 /dev/video1 and /dev/vbi1
> options cx8800 video_nr=1 vbi_nr=1

Been there.
The simplest method I have found is to:

1)  list any modules you do NOT want in the /etc/modprobe.d/blacklist 
file. The kernel will ignore any modules so listed. I use this to 
preveent the kernel loading the cx88 (analog) module for the HD3000 card 
(so /dev/video0 does not get 'stolen').
2)  add lines to /etc/rd.d/rc.local to remove (modprobe -r  thatone ) 
and then add (modprobe thisone) the modules you want, in the order you want.
This route has NO effect on udev rules so no special steps need be 
taken. And it runs last of all boot-up steps (and notwithstanding that 
it is last, it does not affect mythbackend being run as a service).


              R. Geoffrey Newbury			
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           newbury at mandamus.org

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