Maksim Yevmenkin writes:
 > The problem is that as soon as i open isochronous pipe and 
 > start incoming isochronous transfer, the isochronous callback
 > gets called over and over again. Both isoc. pipe and isoc. 
 > transfer have USBD_NO_SHORT_XFER flag set. I also set 
 > configuration #5 for interface 1. The funny part that device
 > says that it got zero bytes from the pipe. It does not affect
 > (or so it seems) the other transfers and everything still works.
 > I also tried ugen driver with the same results. What is up with
 > that?

My experience with isochronous pipes is the same.  I'm working with a
couple of webcams and the isoc callback is invoked repeatedly, but
always with a size of 0.  This occurs in both -stable and -current,
tested on two different UHCI chipsets.  I also played around with ugen
(stock ugen and a userland driver, as well as a "custom ugen") but the
results were the same.

While I have no other USB devices to try out under FreeBSD, my guess
is that the problems are mainly with isoc transfers; there are plenty
of supported devices using bulk and interrupt transfers but there is
only one case I'm aware of that makes use of isoc transfers.
Reportedly a different webcam works under 4.6-RC using ugen and a
userland program (/usr/ports/graphics/vid).

I'm also a USB newbie so I cannot answer your other questions.


Carlos A. Ugarte                                    [EMAIL PROTECTED]

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