Strange RPi USB Audio Issue

[Arne Caspari]

Hi all!

I encounter a strange issue while using USB Audio DACs with the  
raspberry pi:

In my buildroot environment, I get corrupted audio when using USB 2.0  
audio DACs on the raspberry pi. Every once in a while the audio data in  
the usb packets contain only zeroes for some 10-30 samples which  
produce audible clicks in the output.

Now, if I use Raspbian, I can not provoke this issue no matter what.  
The audio is always fine with Raspbian.

I tried anything I could think of to find a difference between my  
environment and Raspbian but I did not find the piece of software that  
is relevant for this failure:

- I used the same kernel image and bootloaders from raspbian in my  
environment - the issue remains
- I used my kernel image on raspbian - the issue still does not occur  
there
- I used the same libasound version like raspbian - the issue remains
- I use the same cmdline settings for USB like raspbian

If anybody has an idea what I could try or what might be the difference  
between raspbian and a generic buildroot environment, I would be very  
grateful to hear about it.


Thanks,


/Arne