[wdmaudiodev] Re: USB Audio Driver/Device problems

  • From: Tim Roberts <timr@xxxxxxxxx>
  • To: wdmaudiodev@xxxxxxxxxxxxx
  • Date: Fri, 06 Nov 2009 15:18:24 -0800

Steve Hayashi wrote:
> I'm pretty sure it is a query failure bug, though it'd be nice if the
> driver tried a little harder with the query.  Even better would be to
> avoid the queries it makes in favor of last known values.

How could it possibly know what the "last known values" are?  Your
device is newly plugged in.  There is no state information.  What if
your device had a manual volume control that had been turned while you
were unplugged?  No, the driver MUST fetch min, max, and cur for all of
your attributes every time you plug in.

> It doesn't get hung up on any one query though.  Sometimes it gets
> hung up on Get_Curr for volume.  Sometimes it's Get_RES for volume.
>  And other times it's Get_Min for treble.

Right.  It's a firmware problem in your device.  It's really just that
simple.  If you want to develop a solution, you must fix your firmware.

You might possibly be able to work around this (for Windows) by writing
a lower filter driver, but if you're failing control endpoint requests,
you're probably going to get behind in isochronous requests at some point.

Isn't alternate setting 2 the same as alternate setting 3?

Tim Roberts, timr@xxxxxxxxx
Providenza & Boekelheide, Inc.


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