[lug] External USB Audio - not connecting driver

[Jed S. Baer]

Hi Everyone.

I just received my Schiit Audio "Full-3" external USB audio device. My
kernel doesn't know what to do with it. It's supposed to be fully UAC2
compatible, and there are UAC2 modules on my system. But when I plug it in,
it gets recognized, but not connected. I think that upowerd is grabbing on
to it, but of course can't do anything with it.

https://www.schiit.com/products/fulla-1 (yes, the URL is "-1" but the text
has been updated)

I have tried manual loading the uac2 and cmedia modules, but that doesn't
accomplish anything. (Verified loaded using lsmod)

I think, in the old days, I could do something with module aliases - it's
been a while since I messed with that. But then, doing some web searches,
I'm not finding much helpful. One StackOverflow thread says you can't do
that. But it points to another that indicates how. Except that there's no
modalias files in /sys/bus/usb/devices/ (recursive) where I could look for
an ID string.

http://unix.stackexchange.com/questions/25919/26065#26065

Not sure whether it's of use, but 
/lib/modules/5.4.0-37-generic/modules.alias has some entries for UAC2, but
none of them are of a device-id form. There are some lines like this:
alias hdaudio:v434D4980r*a01* snd_hda_codec_cmedia
alias hdaudio:v13F69880r*a01* snd_hda_codec_cmedia
alias hdaudio:v13F68888r*a01* snd_hda_codec_cmedia

So, I think if I cna find what that string needs to be, I might get
somewhere.

I'm thinking of seeing whether a new kernel will just fix this, and/or
temporarily blacklisting upowerd.

I can see the device recognized in syslog. Doing lsusb -v on it shows it
identifying as an audio device.

Any thoughts?
-- 
All operating systems suck, but Linux just sucks less
 - Linus Torvalds