[alsa-devel] USB asynchronous mode feedback format

Julian Scheel julian at jusst.de
Thu Oct 14 12:27:38 CEST 2010

Am Donnerstag, 14. Oktober 2010, 10:47:06 schrieb lee188 at singnet.com.sg:
> As I have found out, it is not necessary to have the same EP number for IN
> and OUT for rate feedback to work with a Linux or OSX host.  This may be a
> requirement for Vista/Win7 hosts though.  We are still doing testing.

Hi Alex,

thanks a lot! You made my day (c:
Using EP5 for feedback makes it working. So I now get the data out even in 
async mode. Currently I have a problem left that channel assignment jumps here 
and then. Probably a buffering issue...
Also neither a SRC4192  (sample rate converter) nor a PCM1794 (dac) seem to be 
able to understand what I am sending right now... Not sure why. Looking at the 
measurements it really looks like a proper I2S signal.

Seems you implement something quite similiar as I do. How did you design the 
measurement for actual feedback data to provide? Following the suggestion in 
the spec?


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