My setup is similar to the orginal poster: a laptop (Thinkpad T41p) which uses the snd_intel8x0 module. After upgrading to 2.6.10-morph23 from 2.6.7-gentoo-r13 the onboard sound no longer generates any output. The sound worked just fine under 2.6.7, and I didn't muck with the sound settings.
I've been bashing my head against this for three days, now. Nothing I try makes a bit of difference. ALSA is clearly working: as an experiment, I attached a Plantronics USB headset. When I specify the headset as the output device, sound output is audible. When I specify the onboard intel8x0 sound....nothing. The application behaves as if it is playing, and generates no error messages.
I have unmuted everything and turned up the volume - that is definitely not the problem. I've tried diddling all the sliders while an application is playing, just in case that might make a difference. (It doesn't) Like Acoc, I also see the zeroed values in oss_mixer for the intel_8x0 device in /proc/asound. but I think that is a red herring...I see the same values for the USB device, and its output is just fine.
The IBM has some hardware controls linked to the speaker: volume down, volume up, and mute buttons. When I push the volume up button, the speakers beep loudly, so it's not a hardware problem, and it isn't muted in hardware.
I've tried playing sounds in several applications, so it isn't an application issue. In XMMS with the ALSA output plugin, for example, I can switch between the USB and the intel8x0, but only the USB provides audible output. Other applications give similiar results, as does aplay on the command line.
Based on a hint in another forum post, I tried the steps described at
http://www.linux.w1n-forum.net/#sound - no discerable effect, which isn't really surprising, as the Asus hardware is rather different.
I have ALSA compiled as modules. The module stack, from soundcore to snd_intel8x0 loads without errors and shows up in the output of lsmod. I do not have alsa-driver installed. I have re-emerged every alsa-related ebuild (alsa-tools, alsa-utils, alsa-oss, alsa-lib, alsa-firmware, alsa-headers). I've tried upgrading to udev from devfsd. (I now have a few errors in my logs when devfsd tries to call "unlink" in "GLOBAL".) I have nodes in /dev/sound that match the configuration in /etc/modules.d/alsa. I've tried running alsaconf. I've read the Gentoo ALSA configuration guide. I've read every forum post I could find that looked remotely relevant (and there are a LOT of people complaining that ALSA stopped generating sound after they upgraded to 2.6.10, 2.6.11, or occasionally 2.6.9).
I can post any or all logs and configuration files that might be diagnostic - I won't spam things up by posting everything unless someone requests. At this point, I'm ready to try just about anything.
Any help will be greatly appreciated. I'm stumped.