[alsa-devel] [PATCH] New quirk for USB DAC 08bb:2704
xsdg at xsdg.org
Sat Feb 12 23:53:25 CET 2011
I have one of these:
It's got one of these USB DACs inside
ID 08bb:2704 Texas Instruments Japan
The DAC has a single mixer control, Master, which allows you to adjust
volume and mute/unmute. The fun thing is that the volume adjustment has
no effect whatsoever. On machines running pulse, this means that output
will be at 0dB pretty much all the time. (Of course, this is true of
non-pulse machines also).
The attached patch disables the Master control, which causes pulse to
control levels entirely in software, as it should for this device.
The main downside to this patch is that, while the volume part of the
Master control is non-functional, the mute/unmute aspect does work as
expected. I couldn't figure out how to change the Master control to
just a mute/unmute control, but if someone has suggestions on what to
do, that'd be appreciated. Judging by the comments in the code (and
contrary to what I wrote in the map comment), I presume the mute/unmute
control is the only reason why 08bb:2702 isn't doing this same thing.
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