[wdmaudiodev] Re: Debugging USB audio at the hardware level

  • From: "Tim Roberts" <timr@xxxxxxxxx>
  • To: "WDM Audio List" <wdmaudiodev@xxxxxxxxxxxxx>
  • Date: Thu, 8 Oct 2009 19:37:47 -0700

You wrote:
>By using a Linux OS and reproducing the same problem, we were able to
>get a lead further towards the IN control endpoint from our USB audio
>device. Again, for some reason, the bus driver is resetting the device,
>and it seems that there is a timeout on the in transactions that is
>happening (the IN transactions are at every millisecond, which we
>believe is way too often for a control endpoint sending HID input value
>from the volume up/down buttons on the chip).
>So we went ahead and disabled the HID control device from our USB audio
>device, and the problem goes away. We still want to understand why this
>situation happens.
>Does anybody know if an IN transaction for reporting button control
>value makes any sense to happen every millisecond? It seems out of

Whether or not it makes sense is irrelevant.  It is perfectly legal for it to 
do so, and you are required to respond to control pipe requests within the time 
in the specification.  The fact that you don't is a protocol violation.
Tim Roberts, timr@xxxxxxxxx
Providenza & Boekelheide, Inc.

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