[alsa-devel] [PATCH 0/2] Make ASUS Xonar U3 S/PDIF channel accessible

[Denis Washington]

Hello,

This is my first ALSA patch ever (in fact, also my first kernel patch 
and my first e-mail to this mailing list); as such, I'm sorry when I did 
something wrong and/or didn't follow the procedure properly. I hope you 
can forgive me.

I recently bought an ASUS Xonar U3 USB audio card. It general it works 
well with Linux, but unfortunately, it's PCM output channel is unusable 
for headphones because it allows virtually no volume control (maximum 
loudness is already reach at a volume level of 2 or 3). The card does 
also have a digital (S/PDIF) output channel, which however isn't 
switched on by the Linux USB audio driver:

http://www.mail-archive.com/alsa-user@lists.sourceforge.net/msg28970.html

When I boot into Windows (where the ASUS driver seemingly enables the 
channel) and then reboot into Linux, I can use this channel and control 
volume as expected. It's just this turning on of S/PDIF which is 
missing, as suggested by the alsa-user thread linked to above.

The patchset that follows enables S/PDIF on the Xonar U3 by using the 
(seemingly compatible) mixer quirks code as for the U1, just as done and 
tested by the initiator of the alsa-user thread, together with a very 
minor cleanup (renaming internal xonar_u1_* identifiers to just 
xonar_u_*). The change seems to work well (tested with the 3.7.0 Ubuntu 
kernel as found in today' daily version).

Regard,
Denis Washington

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