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Mailing Lists: lists.debian.org > debian-user > 07 > 073735.html (Request Expert lists.debian.org Support)

Re: Udev. Problems with ordering hardware using /dev/video

From: Nigel Henry <cave.dnb(at)tiscali.fr>
Date: Tue Jul 31 2007 - 18:45:54 EDT


On Tuesday 31 July 2007 23:21, Florian Kulzer wrote:
> On Tue, Jul 31, 2007 at 19:47:51 +0200, Nigel Henry wrote:
> > I've managed to resolve most of my problems on my own, but Udev has
> > beaten me.
> >
> > Sarge is not a problem, as it's using the 2.4.27, or 2.6.8 kernel, and
> > Udev is not in the equation. Etch has a 2.6.8, and a 2.6.17 kernel, and
> > Lenny has a 2.6.11, and a 2.6.17 kernel. The problem is with the 2.6.17
> > kernel that uses Udev.
> >
> > My TV card was set as /dev/video0, and some time later the webcam was set
> > as /dev/video1. this works fine with the pre 2.6.17 kernels (no Udev),
> > and the TV card consistently is /dev/video0, and the webcam /dev/video1.
> > Booting with the 2.6.17 kernel is a different scenario. Very hit and
> > miss. Sometimes I boot up and starting Xawtv, I get the TV /dev/video0.
> > Othertimes I bootup and start Xawtv, and get my webcam /dev/video1.
>
> This flip-flopping is, AFAIK, more the fault of the newer kernel then
> the fault of udev. If the kernel would always load the modules in the
> same order then udev would probably assign the device nodes in a
> consistent manner.
>
> > I've worked with ordering my soundcards, and the lines are quite simple,
> > and have seen that something similar is possible with Udev, although the
> > lines a re a bit more complex. Could someone give me a couple of lines so
> > that my TV card is always /dev/video0, and the webcam is always
> > /dev/video1?
> >
> > Any help gratefully appreciated for fixing this annoying problem.
>
> Post the output of:
>
> udevinfo -a -p $(udevinfo -q path -n /dev/video0)
>
> udevinfo -a -p $(udevinfo -q path -n /dev/video1)
>
> (Only the blocks that have things like "ATTRS{model}" or "ATTRS{vendor}"
> are important.)
>
> --
> Regards, | http://users.icfo.es/Florian.Kulzer
> Florian |

Output below. Bear in mind that /dev/video0 should be the TV card, /dev/video1 the webcam, at least that is how they are loaded with pre Udev kernels.

 ssh 192.168.0.8
Password:
Linux debian 2.6.17-2-686 #1 SMP Wed Sep 13 16:34:10 UTC 2006 i686

The programs included with the Debian GNU/Linux system are free software; the exact distribution terms for each program are described in the individual files in /usr/share/doc/*/copyright.

Debian GNU/Linux comes with ABSOLUTELY NO WARRANTY, to the extent permitted by applicable law.
Last login: Tue Jul 31 20:37:05 2007
djmons@debian:~$ udevinfo -a -p $(udevinfo -q path -n /dev/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"
    DRIVER=="" 

    ATTR{exposure}=="0"
    ATTR{hue}=="128"
    ATTR{contrast}=="54"
    ATTR{saturation}=="110"
    ATTR{brightness}=="124"
    ATTR{sensor}=="OV7620"
    ATTR{bridge}=="OV511+"
    ATTR{model}=="Generic Camera _no ID_"
    ATTR{custom_id}=="0"
    ATTR{name}=="OV511 USB Camera"
    ATTR{dev}=="81:0"

  looking at parent device '/devices/pci0000:00/0000:00:07.2/usb1/1-2':     KERNELS=="1-2"
    SUBSYSTEMS=="usb"
    DRIVERS=="usb" 

    ATTRS{configuration}==""
    ATTRS{maxchild}=="0"
    ATTRS{version}==" 1.00"
    ATTRS{devnum}=="3"
    ATTRS{speed}=="12"
    ATTRS{bMaxPacketSize0}=="8"
    ATTRS{bNumConfigurations}=="1"
    ATTRS{bDeviceProtocol}=="00"
    ATTRS{bDeviceSubClass}=="00"
    ATTRS{bDeviceClass}=="00"
    ATTRS{bcdDevice}=="0100"
    ATTRS{idProduct}=="a511"
    ATTRS{idVendor}=="05a9"
    ATTRS{bMaxPower}=="500mA"
    ATTRS{bmAttributes}=="80"
    ATTRS{bConfigurationValue}=="1"
    ATTRS{bNumInterfaces}==" 1"
Do you need help?X

  looking at parent device '/devices/pci0000:00/0000:00:07.2/usb1':     KERNELS=="usb1"
    SUBSYSTEMS=="usb"
    DRIVERS=="usb" 

    ATTRS{configuration}==""
    ATTRS{serial}=="0000:00:07.2"
    ATTRS{product}=="UHCI Host Controller"
    ATTRS{manufacturer}=="Linux 2.6.17-2-686 uhci_hcd"
    ATTRS{maxchild}=="2"
    ATTRS{version}==" 1.10"
    ATTRS{devnum}=="1"
    ATTRS{speed}=="12"
    ATTRS{bMaxPacketSize0}=="64"
    ATTRS{bNumConfigurations}=="1"
    ATTRS{bDeviceProtocol}=="00"
    ATTRS{bDeviceSubClass}=="00"
    ATTRS{bDeviceClass}=="09"
    ATTRS{bcdDevice}=="0206"
    ATTRS{idProduct}=="0000"
    ATTRS{idVendor}=="0000"
    ATTRS{bMaxPower}=="  0mA"
    ATTRS{bmAttributes}=="e0"
    ATTRS{bConfigurationValue}=="1"
    ATTRS{bNumInterfaces}==" 1"

  looking at parent device '/devices/pci0000:00/0000:00:07.2':     KERNELS=="0000:00:07.2"
    SUBSYSTEMS=="pci"
    DRIVERS=="uhci_hcd" 

    ATTRS{modalias}=="pci:v00001106d00003038sv00000925sd00001234bc0Csc03i00"
    ATTRS{local_cpus}=="ff"
    ATTRS{irq}=="11"
    ATTRS{class}=="0x0c0300"
    ATTRS{subsystem_device}=="0x1234"
    ATTRS{subsystem_vendor}=="0x0925"
    ATTRS{device}=="0x3038"
    ATTRS{vendor}=="0x1106"

  looking at parent device '/devices/pci0000:00':     KERNELS=="pci0000:00"
    SUBSYSTEMS==""
    DRIVERS=="" djmons@debian:~$ udevinfo -a -p $(udevinfo -q path -n /dev/video1)

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/video1':     KERNEL=="video1"
    SUBSYSTEM=="video4linux"
    DRIVER=="" 

    ATTR{card}=="10"
    ATTR{name}=="BT878 video _Hauppauge _bt878__"

Do you need more help?X

    ATTR{dev}=="81:1"

  looking at parent device '/devices/pci0000:00/0000:00:0a.0':     KERNELS=="0000:00:0a.0"
    SUBSYSTEMS=="pci"
    DRIVERS=="bttv" 

    ATTRS{modalias}=="pci:v0000109Ed0000036Esv00000070sd000013EBbc04sc00i00"
    ATTRS{local_cpus}=="ff"
    ATTRS{irq}=="10"
    ATTRS{class}=="0x040000"
    ATTRS{subsystem_device}=="0x13eb"
    ATTRS{subsystem_vendor}=="0x0070"
    ATTRS{device}=="0x036e"
    ATTRS{vendor}=="0x109e"

  looking at parent device '/devices/pci0000:00':     KERNELS=="pci0000:00"
    SUBSYSTEMS==""
    DRIVERS=="" I saw that someone with network device problems, and Udev, was able to specify the devices by name on 2 separate lines, so that Udev always recognised them by name. I don't know if something similar is possible with my situation with the TV card, and the webcam.

Thanks for your concern.

Can we help you?X

Nigel. 

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Received on Tue Jul 31 18:46:44 2007

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