Trying to understand the sound system

Inxsible · 2011-08-24 21:30:06

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?

pigiron · 2011-08-26 04:08:10

Hmm... this is a wild one.

I'm wondering if you get the system back into failure mode and then ran this:

echo 1 > /sys/class/sound/hwCXDY/reconfig

where "X" and "Y" (in "hwCXDY") are some digits for your particular sound card...

if this would do the same thing as when you're reloading the soundcore module.

What that command does is tell the sound driver to reinitialize and parse the codec tree again.

But... I'm still not sure how this would help the situation

Last edited by pigiron (2011-08-26 04:08:57)

Inxsible · 2011-08-26 05:25:15

pigiron wrote:

where "X" and "Y" (in "hwCXDY") are some digits for your particular sound card...

How would I find those digits out ?

Stebalien · 2011-08-26 07:47:44

Inxsible wrote:

pigiron wrote:
where "X" and "Y" (in "hwCXDY") are some digits for your particular sound card...
How would I find those digits out ?

ls /sys/class/sound/hwC?D?

Last edited by Stebalien (2011-08-26 07:49:21)

pigiron · 2011-08-26 18:23:21

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)

Arch Linux

#1 2011-08-24 21:30:06

Trying to understand the sound system

#2 2011-08-26 04:08:10

Re: Trying to understand the sound system

#3 2011-08-26 05:25:15

Re: Trying to understand the sound system

#4 2011-08-26 07:47:44

Re: Trying to understand the sound system

#5 2011-08-26 18:23:21

Re: Trying to understand the sound system

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