Trying to understand the sound system

Question

Here's my problem. My mic didn't work (neither the front mic nor the line-in in the rear), so after some research and trial and error I found that if I do
modprobe soundcore
my mic works on both the jacks
But here's where my confusion lies. This is the output of lsmod |grep snd before probing explicitly for soundcore
[inxs ~ ]$ lsmod |grep snd
snd_hda_codec_analog 78696 1
snd_hda_intel 22122 1
snd_hda_codec 77927 2 snd_hda_codec_analog,snd_hda_intel
snd_hwdep 6325 1 snd_hda_codec
snd_pcm_oss 38818 0
snd_pcm 73856 3 snd_hda_intel,snd_hda_codec,snd_pcm_oss
snd_timer 19416 1 snd_pcm
snd_page_alloc 7121 2 snd_hda_intel,snd_pcm
snd_mixer_oss 15275 2 snd_pcm_oss
snd 57786 8 snd_hda_codec_analog,snd_hda_intel,snd_hda_codec,snd_hwdep,snd_pcm_oss,snd_pcm,snd_timer,snd_mixer_oss
soundcore 6146 2 snd
[inxs ~ ]$
So as you can see, soundcore's already loaded, so why do I have to explicitly load it again to get the mic to work?
Once I add soundcore to my MODULES array and reboot, the lsmod output is also the same as above.
So my question is -- what does the explicit loading of soundcore do, that is not done by auto-loading of that module?

Answer 1

Oh... since your topic is Trying to understand the sound system, that puts you (and me) inside the whole world's population... chuckle. But I thought I'd pass along a document written by probably "The" main ALSA developer that I totally stumbled across just 3 days ago.
Go here:
http://kernel.org/pub/linux/kernel/people/tiwai/docs/
and download the flavor of your choice of the "HD-Audio" document, or simply view it online. It documents the deepest dive into the current ALSA snd_hda_* layers and issues that I've found to date (but still leaves me wanting).
Why that document isn't plastered across the interwebs is beyond me. I only get 11 hits when I search for it... such are the secrets of the ALSA world I guess.
Last edited by pigiron (2011-08-26 18:26:48)