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

  • From: "Martin Gagnon" <mgagnon1@xxxxxxxxxx>
  • To: <wdmaudiodev@xxxxxxxxxxxxx>
  • Date: Mon, 28 Sep 2009 12:49:15 -0400

Thank you Clemens for your input.

We reproduced this behavior in both Win XP and Vista.

Would debugging with a checked OS version would help us get "feedback"
(debug printouts) from the USB host controller driver?

Thank you.

Martin


-----Original Message-----
From: wdmaudiodev-bounce@xxxxxxxxxxxxx
[mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx] On Behalf Of Clemens Ladisch
Sent: Monday, September 21, 2009 1:04 PM
To: wdmaudiodev@xxxxxxxxxxxxx
Subject: [wdmaudiodev] Re: Debugging USB audio at the hardware level

Martin Gagnon wrote:
> If only the OS can tell the USB controller to generate that Reset
> event, then this leads me to my next logical suspect, which are the IN
> transactions that suddenly stop.
> 
> Why would they stop happening? Would it make sense to assume that it
> is also the host controller driver in the OS that stops these IN
> transactions before sending the Reset event isochronous OUT endpoint?

The reset has no destination address; it's a special state of the USB
signal lines and affects all devices on that bus.

The OS will (try to) stop all scheduled transactions before resetting.

> Meaning that a problem happened prior to the IN transactions stopped?

Yes.  Unfortunately, there is no indication why the OS/driver decided
to reset.  Does this happen with other OSes?


Best regards,
Clemens
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