I use HP Compaq nx6325 notebook with ATI – SB450 HDA Audio, with Ubuntu Feisty for x64.
This setup has a strange problem that it can’t switch off speakers when a headphone is connected (and some times vice versa). So Googled a bit and read a couple of postings in the forums.
One of the suggestions was to “rmmod snd-hda-intel && modprobe snd-hda-intel probe_mask=8 model=auto”.
I tried this approach and there was NO SOUND, the best part is no sound card was detected. I reinstalled kernel, alsa-drivers and tried many utilities.
Finally something struck me and then I found that /dev/dsp and /dev/mixer character devices had mysteriously disappeared.
So I went ahead and created this device “mknod /dev/dsp c 14 3”.
Voila!! Now, there is sound every where; I can get a sound sleep 🙂