[wdmaudiodev] Re: wdmaudiodev Digest V6 #170

  • From: Steve Hayashi <sthayashi@xxxxxxxxx>
  • To: wdmaudiodev@xxxxxxxxxxxxx
  • Date: Fri, 6 Nov 2009 09:19:44 -0500


Thanks for responding to me.  You're probably correct in that this is a
firmware bug, and that the only way to really fix it is to just write my own
drivers for it.  Writing a device driver is something I've never done
before, but I've always been curious to try it.  This is an incredibly
simple device from an I/O perspective, just USB in and RCA audio out and
1/8" plug out.  There's a volume dial for headphone output, but none of that
is reported back.  No digital volume control, no eq at any level.

Anyways, with the member variable, it stalls at different points.  Sometimes
it stalls at the Get_Curr for volume.  Sometimes it's Get_Min for volume.
 Other times it stalls at Get_Res for treble.  Sometimes it doesn't stall at
any thing at all, and that's when it starts working.

Given the simple nature of the audio device, it always reports back with the
same information for all of them, so it seems unnecessary to query this
information, when it could be stored.  Especially since a stall response to
the query seems to break the driver i.e. when the host receives the stall
response, it stops querying other variables.

I have a feeling that this will pretty much be happy with just Isochronous
transfers, so I'd love to get it to a stage where all I need to do is stream
audio packets to it.


Clemens Ladisch Wrote:

> Steve Hayashi wrote:
> > Unfortunately, my device will send a stall response to the member variable
> > query
> Which member variable?  Is the query correct, i.e., do the device's
> descriptors indicate that that query should be supported?
> This looks like a typical firmware bug; many low-quality USB devices
> have not been written against the spec but to work with some random
> Windows version that was currently available for testing.
> > My primary goal is to get the usb audio device working normally all the
> > time, ideally through some minor change that I was previously unaware of.
> Well, neither replacing the device's firmware not writing your own
> USB audio driver looks like a minor change.
> Best regards,
> Clemens

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