[alsa-devel] UCM file lookup logic

[Tanu Kaskinen]

On Mon, 2020-01-27 at 09:07 +0100, Jaroslav Kysela wrote:
> Dne 27. 01. 20 v 4:38 Tanu Kaskinen napsal(a):
> > Hi all,
> > 
> > I was looking at the UCM files, and most paths have the following
> > structure:
> > 
> >      <cardname>/<cardname>.conf
> > 
> > I noticed that the "HDA Intel PCH" configuration uses some other
> > scheme:
> > 
> >      HDA Intel PCH/HDAudio-DualCodecs.conf
> >      HDA Intel PCH/HDAudio-Gigabyte-ALC1220DualCodecs.conf
> >      HDA Intel PCH/HDAudio-Lenovo-DualCodecs.conf
> > 
> > How are the directory and file names determined? If I write
> > configuration for some random sound card that I don't have myself,
> > where do I find the various identifiers in the alsa-info output? I
> > don't even really know for sure what the <cardname> in the first
> > example is, I've been assuming it's the name that appears in the square
> > brackets in /proc/asound/cards.
> 
> The ucm has scheme <longname>/<longname>.conf and 
> <drivername>/<drivername>.conf (fallback).
> 
> The ucm2 has scheme <drivername>/<longname>.conf and
> <drivername>/<drivername>.conf (fallback).
> 
> Example proc output:
> 
>   2 [device         ]: USB-Audio - USB Video device
>                        317GAWCM001LON3BC1AZ USB Video device at 
> usb-0000:00:14.0-4.2.4, high speed
> 
> The driver name is 'USB-Audio' here. The longname is '317GAWCM001LON3BC1AZ USB 
> Video device at usb-0000:00:14.0-4.2.4, high speed' here. The name in brackets 
> is the user selectable identifier for the card (card id). It can be used 
> instead the sound card number.

Thanks, seems pretty straightforward!

> > I think the lookup logic should be explained in the ucm2/README.md
> > file. I can write a patch if someone expains the logic to me, but
> > probably it's easier if you just write the patch yourself.
> 
> Yes, a better documentation for the internals is missing. Unfortunately, I hit 
> other real problems with the current UCM logic and trying to resolve them. 
> Unfortunately, I am interrupted with other things so things are going slowly 
> than I want.

Does this mean that the file lookup logic is likely to still change?

-- 
Tanu

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