audio problems with custom kernel (Intel 810 + AC97 Audio)

[Count László de Almásy <calmasy@gmail.com>]

I'm having some problems with audio now that I've started using the
2.6.9 kernel that I built.  Audio did work with the
2.6.8-3-amd64-k8-smp kernel that came with the install image.

lspci shows the audio controller:

  rosebud:~# lspci | grep -i audio
  0000:00:1f.5 Multimedia audio controller: Intel Corp. 82801EB/ER
(ICH5/ICH5R) AC'97 Audio Controller (rev 02)

The right drivers seem to be loaded:

  rosebud:~# lsmod | grep -i audio 
  i810_audio             40344  0 
  ac97_codec             21016  1 i810_audio
  soundcore              12256  2 i810_audio,snd

However no sound comes out when I play an audio file.

Looking at dmesg output, it seems the controller shows up, but only
on one line:

  rosebud:~# dmesg | grep -i audio
  Intel 810 + AC97 Audio, version 1.01, 18:06:18 Nov  5 2004

As opposed to several lines when looking at the dmesg output for the
previous kernel:

  rosebud:/var/tmp# grep -i audio dmesg.2.6.8-3-amd64-k8-smp 
  Intel 810 + AC97 Audio, version 1.01, 00:32:26 Aug 30 2004
  i810_audio: Primary codec has ID 0
  i810_audio: Audio Controller supports 6 channels.
  i810_audio: Defaulting to base 2 channel mode.
  i810_audio: Resetting connection 0
  i810_audio: Connection 0 with codec id 0
  ac97_codec: AC97 Audio codec, id: ADS116 (Unknown)
  i810_audio: AC'97 codec 0 supports AMAP, total channels = 2
  i810_audio: setting clocking to 48607

Any ideas what the problem might be or how I can debug this?