help naming video devices

help naming video devices

[Richard Ray]

I have 2 video devices LML33 and PV155

$ lspci
06:00.0 Multimedia video controller: Zoran Corporation ZR36057PQC Video 
cutting chipset (rev 02)
07:08.0 Multimedia video controller: Brooktree Corporation Bt878 Video 
Capture (rev 11)
07:08.1 Multimedia controller: Brooktree Corporation Bt878 Audio Capture 
(rev 11)
07:09.0 Multimedia video controller: Brooktree Corporation Bt878 Video 
Capture (rev 11)
07:09.1 Multimedia controller: Brooktree Corporation Bt878 Audio Capture 
(rev 11)
07:0a.0 Multimedia video controller: Brooktree Corporation Bt878 Video 
Capture (rev 11)
07:0a.1 Multimedia controller: Brooktree Corporation Bt878 Audio Capture 
(rev 11)
07:0b.0 Multimedia video controller: Brooktree Corporation Bt878 Video 
Capture (rev 11)
07:0b.1 Multimedia controller: Brooktree Corporation Bt878 Audio Capture 
(rev 11)

$ udevinfo -q path -n /dev/video0
/class/video4linux/video0
$ udevinfo -a -p /class/video4linux/video0

Udevinfo starts with the device specified by the devpath and then
walks up the chain of parent devices. It prints for every device
found, all possible attributes in the udev rules key format.
A rule to match, can be composed by the attributes of the device
and the attributes from one single parent device.

   looking at device '/class/video4linux/video0':
     KERNEL="video0"
     SUBSYSTEM="video4linux"
     SYSFS{name}="LML33_0_"
     SYSFS{dev}="81:0"

$ udevinfo -q path -n /dev/video1
no record for 'video1' in database
$ udevinfo -q path -n /dev/video2
no record for 'video2' in database
$ udevinfo -q path -n /dev/video3
no record for 'video3' in database
$ udevinfo -q path -n /dev/video4
no record for 'video4' in database

The problem is sometimes when I boot the LML33 is /dev/video0 and 
sometimes /dev/video4
I tried a udev rule
SUBSYSTEM="video4linux", SYSFS{name}="LML33_0_",SYMLINK="lml33"
but it doesn't work
What do I need to do to get consistant device naming?

Thanks
Richard Ray

Re: help naming video devices

[Bryan Kadzban]

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Richard Ray wrote:
> What do I need to do to get consistant device naming?

Use the existing symlinks in /dev/v4l/by-path perhaps?

Or, if v4l_id supports it from your capture card, udev will create
/dev/v4l/by-id links as well, which may work better for you (they're
based on serial # and bus).

These are both supposed to be stable and unique.  Of course, you need to
be using at least a recent version of udev (i.e. one from *long* after
it changed to stop using SYSFS{} anymore)...


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Re: help naming video devices

[Richard Ray]

On Tue, 14 Jul 2009, Bryan Kadzban wrote:

> Richard Ray wrote:
>> What do I need to do to get consistant device naming?
>
> Use the existing symlinks in /dev/v4l/by-path perhaps?
>
> Or, if v4l_id supports it from your capture card, udev will create
> /dev/v4l/by-id links as well, which may work better for you (they're
> based on serial # and bus).
>
> These are both supposed to be stable and unique.  Of course, you need to
> be using at least a recent version of udev (i.e. one from *long* after
> it changed to stop using SYSFS{} anymore)...
>
>
I am using CentOS 5.3, kernel 2.6.18-92.1.22.el5.centos.plus, and
udev-095-14.20.el5_3 package

There is no /dev/v4l directory so what are my options for fixing this?

Re: help naming video devices

[Greg KH]

On Wed, Jul 15, 2009 at 09:03:41AM -0500, Richard Ray wrote:
> On Tue, 14 Jul 2009, Bryan Kadzban wrote:
> 
> > Richard Ray wrote:
> >> What do I need to do to get consistant device naming?
> >
> > Use the existing symlinks in /dev/v4l/by-path perhaps?
> >
> > Or, if v4l_id supports it from your capture card, udev will create
> > /dev/v4l/by-id links as well, which may work better for you (they're
> > based on serial # and bus).
> >
> > These are both supposed to be stable and unique.  Of course, you need to
> > be using at least a recent version of udev (i.e. one from *long* after
> > it changed to stop using SYSFS{} anymore)...
> >
> >
> I am using CentOS 5.3, kernel 2.6.18-92.1.22.el5.centos.plus, and
> udev-095-14.20.el5_3 package
> 
> There is no /dev/v4l directory so what are my options for fixing this?

Upgrading to a new version of udev, and a kernel released in the past 3
years :)

seriously, take this up with centos if you want to support this, it's
not something that is going to work with your existing system due to the
oldness of the packages.

good luck,

greg k-h