[alsa-devel] EeePC 1005PE microphone is "stereo only", silent in mono

Pavel Roskin proski at gnu.org
Wed Aug 3 17:29:30 CEST 2011

On 08/03/2011 04:56 AM, Paul Menzel wrote:
> Am Mittwoch, den 03.08.2011, 08:26 +0200 schrieb Takashi Iwai:
> […]
>> From: Takashi Iwai<tiwai at suse.de>
>> Subject: [PATCH] ALSA: hda - Fix digital-mic mono recording on ASUS eeePC

Tested-by: Pavel Roskin <proski at gnu.org>

>> stereo PCM, thus you can't record a mono stream from the stereo stream as
>> is; the summing the stereo signal results in almost zero level, and you'll
> Should »the summing« be »in summary«?
>> hear only noise.

Actually, I was hearing almost complete silence.  I was able to hear a 
very faint voice if I would scream at the microphone while recording. 
But I cannot vouch for that and I'm not in the environment to reproduce 
that test :)

The noise is a different thing.  I would get it from the microphone 
without "model=auto" on the current sound-2.6/master, but not on 3.0. 
Perhaps some other initialization was tied to "model=auto".  But this 
patch appears to remove the need to use that parameter.

>> As a workaround, use ALC269-specific COEF to manipulate the dmic route
>> for mono, like used for ALC271x.  Since this is implemented as a fix-up
>> and the auto-parser works fine for eeePC, the patch drops the model
>> quirk entries for them, too.
> So as a consequence everyone using `model=auto` can drop that from
> `/etc/modprobe.d/`?

Yes.  Disclaimer: I only tried it once, and I rebooted after having 

> I do not know how high the regression chance might be, but if there is
> any, maybe split the patch and write all models in the commit summary
>          ALSA: hda - Use auto parser for ASUS UX50, Eeepc P901, Eeepc S101 and P1005HA

You are not following the naming scheme you are suggesting :)

By the way, the full name of my laptop as written on the underside is 
ASUS Eee 1005PEB.  I assume "B" is for "brown".  dmidecode gives 1005PE 
for the system and 1005P for the base board.

The CPU is Intel Atom N450.  I looked for 1005HA online, and they are 
said to have N270.

I assume 1005HA and 1005PE are different models.  Of course, the sound 
chip may be the same.

Pavel Roskin

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