At Thu, 30 Sep 2010 23:18:51 +0600, Valentine Sinitsyn wrote:
Hello,
I happened to spend last couple of evenings figuring out what's wrong with microphone on my laptop (Lenovo Y550P, in case you are interested in). It has Intel HDA soundcard with Realtek 272 codec. No, I'm not going to ask for a help on devel mailing list, at the very least because I know what's wrong myself. But this knowledge poses some questions regarding snd-hda-intel kenel driver (more precisely, patch_realtek.c, which is part of it) I want to clarify. Anyway, sorry for the long intro :)
It quickly appeared that AUD_IN widget of the codec (NID 0x09) has no way to be unmuted - its input amplifier is muted at the very beginning of alc662_init_verbs and is not connected to any ALSA control (maybe it should). I remembered the mic was working some time ago, so I've skimmed through kernel versions and found the offending commit:
http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdif...
One can clearly see from it that before it was applied (i.e. Linux 2.6.34), this widget was unmuted in alc662_auto_init_verbs (thus it happened to every auto-configured card, including mine), but it is not unmuted anymore (as far as I can see, for any model except maybe ecs - I haven't dug into this too much).
The question is if it is intentional (i.e. there should be some ALSA switch connected to 0x09 input amplifier) or is it a bug?
If the NID 0x09 not controllable via a mixer element but it influences on the capture behavior, then it's a bug. The change above should influence only the default value, which will be usually overridden by alsactl, PA or whatever.
Could you give alsa-info.sh output of your system? Run with --no-upload option and attach the output.
thanks,
Takashi