On Wed, Mar 27, 2013 at 12:52:14 +0100, Daniel Mack wrote:
On 27.03.2013 12:47, Torstein Hegge wrote:
On Wed, Mar 27, 2013 at 11:09:01 +0100, Clemens Ladisch wrote:
Torstein Hegge wrote:
The C-Media CM6631 USB receiver doesn't respond to changes in sample rate while the interface is active. The same behavior is observed in other UAC2 hardware like the VIA VT1731.
Might it be possible that these devices have reset the interface (see UAC2 section 3.16.3), and that the driver hasn't noticed this because it doesn't handle Active Alternate Setting Control interrupts?
If that was the case, wouldn't the device be in altsetting zero after the sample rate set and not be able to output sound at all? And as long as the current altsetting supports the target sample rate as reported in /proc/asound/card1/stream0, Active Alternate Setting Control shouldn't have to be invoked.
You could just try and catch that currently unhandled interrupt. We should support that anyway at some point ...
It doesn't look like snd_usb_mixer_interrupt_v2() is invoked on sample rate changes. As far as I can tell, that should be invoked on any interrupts, but it was never triggered, so I might be wrong.
Torstein