Re: unexpected webcam side effect

On Saturday 07 July 2007 02:28, Tom Horsley wrote:
On Fri, 6 Jul 2007 22:34:56 +0200

Nigel Henry <cave.dnb@xxxxxxxxxx> wrote:
On Friday 06 July 2007 14:16, Tom Horsley wrote:
Here's some behavior I've never seen before:

https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=247224

I don't know about your problem specifically, but would you post the
output from.
cat /proc/asound/cards

First do this booting up with the webcam unplugged, then shutdown, plugin
the webcam, reboot, and run cat /proc/asound/cards again.

It will be interesting to see if, when the webcam is plugged in, it is
being detected as card0. ( that is, the usb mike part of it), and your
sound card is being set as card1.

I added the above info to the bugzilla, but there is no card1, the nvidia
sound just completely disappears.

Can you also post the output of /sbin/lsusb with the webcam plugged in,
and also the output from /sbin/lsmod.

I think all the other info is already buried in some of the log files
I added to the bugzilla.

However, the most interesting fact so far is that if I rename the
snd-usb-audio.ko kernel module so it can't be loaded, I can boot with
the webcam plugged in, and everything (except, of course, the USB
microphone) works fine.

From what you say about renaming snd-usb-audio.ko, I think you may have run
into an old problem, that used to be present on earlier versions of FC, but
appeared to be fixed on FC4, 5, and 6. I've only just installed F7, but the
problem has returned.

Basically the USB comes up early in the boot sequence, and anything that uses
snd-usb-audio would be set as card0, and the sound card as card1. This was my
experience with my usb midi keyboard. Alsa was trying to use it as a
soundcard.

Looking now at how this problem has returned on F7. Cat /proc/asound/cards
showed my usb midi keyboard as card0, and bt878 as card1, and my soundcard
completely missing. bt878 is a module for the TV card, and is always
problematic. Some distros create an index=2 for it, as it has a habit of
grabbing card0. In my case it can't as the usb has already grabbed card0.

Ok. now for the fix, at least in my case. You need to add a couple of lines
in /etc/modprobe.conf, as below.

alias snd-card-1 snd-usb-audio
options snd-usb-audio index=1

I also run as root. depmod -a after making changes to /etc/modprobe.conf.

That fixes the problem for me, and my modprobe.conf now looks like this,
having added another options line for the annoying bt878.

alias eth0 8139too
alias scsi_hostadapter pata_via
alias snd-card-0 snd-emu10k1
options snd-card-0 index=0
options snd-emu10k1 index=0

alias snd-card-1 snd-usb-audio
options snd-usb-audio index=1

options snd-bt87x index=2

It's worth a try Tom. Just rename snd-usb-audio.ko back to it's original name,
add the 2 lines to /etc/modprobe.conf, plug in the webcam, and reboot.

All the best.

Nigel.






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