[alsa-devel] Question about surround default pin config

Takashi Iwai tiwai at suse.de
Thu Aug 9 15:01:39 CEST 2012

At Thu, 09 Aug 2012 14:51:40 +0200,
David Henningsson wrote:
> Hi,
> Sometimes it's better to just ask than getting confused trying to figure 
> it out yourself.
> When you have 2 stereo pairs of line-out or speaker, they are meant as 
> either 4.0 (front left, front right, rear left, rear right), and 
> sometimes they are meant as 2.1 (front left, front right, unused, lfe).
> We should support both variations, I assume.
> What is really the way to write my pin fixups to specify either 4.0 or 
> 2.1? Are there any de-facto standards?
> If I look at e g check_output_sfx (in hda_auto_parser.c), it looks like 
> it would be impossible to have 2.1, i e, impossible to have LFE without 
> also having rear left and rear right. But I might be missing something?

Right, as of now, 2.1 configuration isn't supported by the parser.
It's a bit messy.  We can check the associated number whether it's 4.0
or 2.1, but I don't think there is a strict definition to
differentiate between them.  So, it'd end up with a guess work.

Of course, we can add some special flag beforehand and let auto-parser
handle 4.0 as 2.1.


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