[LAU] Audio Class 2.0 with Sound Devices USBPre2 (was: Recommended USB interface with 2 XLR inputs?)

Clemens Ladisch clemens at ladisch.de
Wed Oct 12 09:24:09 UTC 2011

Bernardo Barros wrote:
> Ok, I reconnected without pressing "1".
> Bus 002 Device 002: ID 0926:0202
> Device Descriptor:
>   bNumConfigurations      2

Okay, this device now has two configurations, one almost the same as the
one forced by "1", and one for audio class 2.0.  As long as the driver
does not know that it needs to switch to the second configuration, it
will use the first one.

The only difference between the two audio class 1 configurations is that
the "1" one has bInterval=1 for all endpoints while the other one has
bInterval=4.  This seems to trip up the driver; please show any error
messages that show up in the system log (/var/log/messages or the output
of dmesg) when you try to play something.

We also need a quirk to enable the audio class 2.0 configuration.
(This isn't really device-specific; this should probably be done for all
devices with two such configurations.)


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