linux-kernel - Re: [alsa-devel] Bugs on aspire one A150

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Message-ID: <s5heiwwzim7.wl%tiwai@suse.de>
Date:	Tue, 17 Mar 2009 08:57:52 +0100
From:	Takashi Iwai <tiwai@...e.de>
To:	Maxim Levitsky <maximlevitsky@...il.com>
Cc:	Andreas Mohr <andi@...as.de>, linux-kernel@...r.kernel.org,
	alsa-devel@...a-project.org,
	Kernel Testers List <kernel-testers@...r.kernel.org>
Subject: Re: [alsa-devel] Bugs on aspire one A150

At Tue, 17 Mar 2009 02:52:19 +0200,
Maxim Levitsky wrote:
> 
> On Mon, 2009-03-16 at 22:22 +0100, Andreas Mohr wrote:
> > Hi,
> > 
> > On Mon, Mar 16, 2009 at 09:28:39PM +0100, Takashi Iwai wrote:
> > > At Mon, 16 Mar 2009 19:06:38 +0100,
> > > Andreas Mohr wrote:
> > > > I just tried connecting a headset and switching to E-Mic.
> > > > What I can say is:
> > > > - opposite levels does NOT happen there (E-Mic is "analog micro"-based, right?)
> > > > - leaving E-Mic unplugged will actually record from i-Mic (due to properly
> > > >   working EAPD mechanism, right?)
> > > 
> > > The record from mic-jack is via analog path.  The phase-inversion
> > > appears only for digital-mic, AFAIK.
> > 
> > Thought so.
> > 
> > > > One question still: is this a hardware defect (i.e. could this possibly
> > > > be swapped cables of the microphone connector in this model or so?
> > > > Not plausible but...), or is this an existing property
> > > > of the HDA's dig-mic base? You indicated it's the latter I think...
> > > 
> > > My guess is that it's a hardware implementation.
> > > Maybe for the noise suppression via mic array.
> > 
> > Not sure what this means.
> > 
> > > The question is whether the left / right channels recorded from
> > > digital mic are really raw data, or they are for modified data
> > > (for differential, etc)...  It's hard to guess without the actual
> > > data.
> > 
> > I don't quite follow you here. Is there anything I could do about this?
> > 
> > Thanks,
> > 
> > Andreas
> 
> 
> What about exposing the i-mic as a mono only device to userspace?
> It is mono after all?

No, it's a mic-array.  And HD-audio cannot handle a mono stream.


Takashi
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