[alsa-devel] Quirk to disable master volume control in PCM2702
clemens at ladisch.de
Tue Nov 17 10:04:30 CET 2009
Javier Kohen wrote:
> I've written the attached patch to disable the master volume control
> in this chipset. The datasheet  documents two independent channel
> volume controls, one master mute control and one master volume
> control. However, at least on my device (a Fubar USB DAC), the master
> volume control always returns USB stalls when queried for any of its
> parameters (min/max/res/cur).
I'd guess that Windows ignores the master volume when it finds
channel volume controls, so this function was never actually tested.
> However, it seems that either the USB specs are wrong,
They are abominations written by committees.
> or my USB hub or the card are buggy.
Your hub is certainly buggy ...
> the PCM2702 and my motherboard don't interact well. After a while the
> sound is degraded, first into a hiss, then into pure noise.
... the card too.
Your patch looks good; please provide a log message and a Signed-off-by
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