[mythtv-users] UDEV rules for tuner numbering consistency

btsglw btsglw at gmail.com
Thu Jan 17 21:35:57 UTC 2008

On 17/01/2008, Brian Jameson <tech at jameson.co.uk> wrote:
> My Fedora 8, kernel running version 0.20.2-171 of MythTV has
> a Nova T 500 twin tuner and a Nova S tuner card in it. So all DVB based.
> Like other users on this list I have suffered from the tuner cards changing
> their numbering/identification depending on cold starts/re-boots and now
> software updates. After much googling, reading and trying my hand at
> creating some UDEV rules I have totally failed to make any progress in
> creating a rule that does anything, let alone making symlinks of a
> consistent nature to remove/bypass the start up naming/numbering issue,
> which seems to be the way around the problem.

This is how I did it when I had my PVR-350 installed alongside two
Avermedia 777 cards. All the cards have MPEG-2 encoders while the
Avermedias also have DVB-T. These all created /dev/videoN entries and
I wanted to set them up to always correspond to fixed entries in /dev
I goy
My rules file:
KERNEL=="video[0-9]*",SYSFS{name}=="ivtv? encoder MPEG",
ID=="0000:02:09.0", SYMLINK="video_ivtv"
KERNEL=="video[0-9]*",ID=="0000:02:07.0", SYMLINK="video1_saa"
KERNEL=="video[0-9]*",ID=="0000:02:08.0", SYMLINK="video2_saa"

I used the cards' PCI IDs (as given by lspci) to identify them. In the
case of the Avermedias, this was the only way to differentiate between
them as they are identical cards.  The rules create two symlinks,
video1_saa and video2_saa for the first and second Avermedia cards
respectively. For the PVR-350 I used a combination of the PCI ID and
part of SYSFS name (hence the ? after ivtv) to call create a
video_ivtv symlink.  The only disadvantage to using the PCI ID is
you'll need to update your rules if you move the cards to different
slots on your motherboard.



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