[alsa-devel] Internal Mic Boost channel is unused

David Henningsson david.henningsson at canonical.com
Thu Sep 12 20:43:47 CEST 2013

On tor, 2013-09-12 at 09:52 -0600, Nathanael D. Noblet wrote:
> Hello,
>     I have an issue I'd like to help completely solve. Unfortunately I 
> only have a tenuous grasp of what is actually going on so some of this 
> could be wrong/include errors.
>    Here's what I know.
>   1) I have the following hardware (alsa-info attached).
>   2) The internal microphone requires that the mic boost channel be 
> something other than 0 to function properly.
>   3) Changing what pulseaudio expects things to be labelled causes the 
> problem to go away. (via the attached patch to 
> /usr/share/pulseaudio/paths/analog-input-mic.conf).
>    From the discussion with David Henningsson (diwic on IRC). It seems 
> that pulse doesn't expect a Mic Boost channel to be used with internal 
> microphones. As such to fix this particular hardware, the driver would 
> need to make the internal mic boost be labelled "Internal Mic Boost" as 
> opposed to Mic Boost, which is then is used for both external and 
> internal mics.
>    I'd love to be able to help any way I can to get these fixed once and 
> for all. Let me know if you need more information or what not.

So I saw that you had two selector nodes (0x17 and 0x18), so I figured
one could be "Internal Mic Boost" (for internal mic) and the other one
"Mic Boost" (for external mic).

However, according to the BIOS, you actually have *two* external mic
jacks. Is this correct? It could possibly be that one of them is part of
a headset jack. This might be related to what's confusing the driver, so
perhaps if we just removed the fake mic input that would make things

// David

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