[wdmaudiodev] Re: USB Audio Driver/Device problems

  • From: Steve Hayashi <sthayashi@xxxxxxxxx>
  • To: wdmaudiodev@xxxxxxxxxxxxx
  • Date: Fri, 6 Nov 2009 21:43:33 -0500

To give a bit more background, this is a device I bought many years ago.
 The label on the bottom gives the manufacture date at Nov 2001.

I just took it apart now.  It uses a Philips UDA1321 USB DAC and a Microchip
24LC16B EEPROM.  I couldn't guess where exactly the problem lies here
without doing some component substitution, but I'm doubtful that I can fix
any problem that's burned to silicon.  Maybe if I use a faster EEPROM,
though it's likely that the values it needs to find are internal.

Oh well.  Thank you for all your help.


On Fri, Nov 6, 2009 at 6:18 PM, Tim Roberts <timr@xxxxxxxxx> wrote:

> 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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