[alsa-devel] USB asynchronous mode feedback format

[Alex Lee]

On Fri, 2010-10-15 at 14:08 +0200, Julian Scheel wrote:

> 
> Besides my I2S/DAC troubles, I still seem to have some problem with the async 
> mode. Actually my buffers are permanently overflowing (not slightly, but very 
> extreme). So far I do not regulate the feedback data, but send a constant 
> value of 48 - As I expect 48 samples per USB frame.
> 
> So my data is (48<<13):
> 
>     char data[4];
>     data[0] = 0x00;
>     data[1] = 0x06;
>     data[2] = 0x00;
>     data[3] = 0x00;
> 
>     AUDDSpeakerDriver_WriteFeedback(data, 4,
>                     (TransferCallback)FeedbackSent,
>                     NULL);
> 
> Whenever the feedback was sent (ie it was queried by the host), this method is 
> called again and it sends the feedback again.
> Is this ok in general or is there some basic problem with this feedback style?
> 

UAC data should be Big Endian.  Send the LSB byte first.

Alex