Thursday, September 23, 2004 2:21 PM: Alan Stern
>
> When you say that nothing comes across, do you mean that your
> driver finds the actual_length for each frame in the
> completed URBs is 0? Or do the frames have an error code
> attached? Or do the URBs simply fail to complete? What
> exactly is happening?
Here's what happens when I start the request...(two URBs, each
requesting 100 frames, reap-read-submit loop):
1) Both URBs are submitted.
2) Loop to reap is started.
3) URBs with actual_length=0/error_count=0 are returned constantly. (I
assume that it waits for 100 frames of "nothing" and then unblocks the
REAP ioctl to return. The timing looks about right for that.)
4) I unplug the S/PDIF input to the device and plug it back in.
6) Several more URBs are returned with actual_length=0/error_count=0.
7) Streaming starts, with each URB missing 4/5 frames about evenly
spaced throughout. (The initial URB at the start of streaming is
partially full...as you might expect.) Note that it's not the same
frames in each URB that are missing data. If you concatenated all the
frames together the missing frames would be evenly (almost) spaces
throughout.
When I was running 2.4, the only change to this was that data would
start streaming as soon as the URBs were submitted. In 2.6 I have to
"reinitialize" the streaming by unplugging the S/PDIF input and plugging
it back in to kick-off the data.
I could almost get over the reinit stuff if it didn't *still* drop
frames.
(I hope that's detailed enough...feel free to ask for more information.
I can always hack up my demo-code to provide more information about each
URB.)
Thursday, September 23, 2004 2:21 PM: Alan Stern
>
> Certainly it's possible that you're facing a hardware
> failure. Ideally you should test by running Linux on the
> same computer that you use for Windows XP.
Heh...maybe someday.
Oh, and the controller is reported as
VIA Technologies, Inc. VT82xxxxx UHCI USB 1.1 Controller
in /proc/bus/usb/devices.
Paul Braman
Paul<dot>Braman<at>NielsenMedia<dot>com
Senior Engineer
Engineering and Technology
Nielsen Media Research
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