NEC B1 HC chokes with full BW USB2 ISO IN stream

Greetings,

I have tracked down a bug that looks for all the world like it is caused
by the NEC B1 HC on the Adaptec USB2 PCI interface card I have. The
host is a MP Athlon system running XP SP1 with the Adaptec card using
the NEC B1 EHCI controller and a separate VIA EHCI controller on the
mobo. Both controllers are using the Microsoft usbehci.sys driver
version 5.1.2600.1243.

When running a full bandwidth ISO stream from a USB camera (3072
bytes/microframe), the NEC controller chokes with
USBD_STATUS_ISO_NOT_ACCESSED_BY_HW (c0020000). It does it horribly when
running on a MP boot. If I run on a UP boot of the same machine (same
HC driver), it is still there but not as bad. Now if I switch the
camera over to the VIA controller, everything else I think exactly the
same, the error goes away entirely. It is gone on both the MP and UP
boots.

Before I checked the VIA HC, I thought it was the camera being too slow
and not responding to the IN token in enough time. But after seeing the
difference with the VIA HC, I looked a little more carefully and saw on
my bus analyzer that indeed the IN token is never sent. So it is
clearly on the host end. It is always the third transaction in the
microframe that fails; after two successful transactions.

I was really surprised that a HC would fail like that. I looked online
to see if there were any known troubles with that particular HC, but I
did not see anything. Anyone have any ideas??


Best regards,

Tom Udale


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