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From: Gianluca Varenni on 2 May 2008 11:46
Can it be a buggy USB hub?

Just my two cents
GV


--
Gianluca Varenni, Windows DDK MVP

CACE Technologies
http://www.cacetech.com



"Armageddon" <Armageddon(a)discussions.microsoft.com> wrote in message
news:F800F5FC-0F95-47FF-AC76-6375216EF142(a)microsoft.com...
> I have a full speed USB device that I'm developing that uses usbser.sys.
> I found that if I connect the device directly to my Dell laptop everything
> works find. If I connect the device through a high speed USB 2.0 hub
> everything is very flaky. I see hangs when opening the com port, Windows
> lockups, and other wierd falures.
>
> I found a workaround. If I disabled the enhanced USB controller in
> device manager to force the hub to use full speed everything is rock
> solid.
> So this makes me think the problem is either a bug in Windows or a bug
> with
> the Intel chipset in my Dell Inspiron laptop.
>
> 1. Is this a known bug in usbser.sys or Windows?
> 2. What do I need to do to report the problem?
>
> My operating system is Vista SP1.


From: Armageddon on 2 May 2008 12:56


"chris.aseltine(a)gmail.com" wrote:

> On May 1, 9:29 pm, Armageddon <Armaged...(a)discussions.microsoft.com>
> wrote:
>
> > And Windows is bug free?
>
> Did I say that?
>
> > The firmware on the device also doesn't care if a hub is used or not. The
> > device is a full speed device so I'm confused how having a high speed link
> > between the hub and the PC can make a difference as far as the device is
> > concerned. Doesn't the link from the hub to the device simply look like a
> > plain full speed link?
>
> Get a bus analyzer and compare traces between connecting it directly
> and connecting it through a hub, and look for errors. If your device
> is going wild on the wire, you could potentially bugcheck the machine,
> but that's not really the host's fault (inasmuch as you're not going
> to get a hotfix to work around a device's buggy behavior).
>
> > I'm also confused why Windows malfunctions. It's not just that the device
> > doesn't work. Isn't the driver stack different if a hub is used? Perhaps
> > it's some kind of wierd interaction between device drivers.
>
> Assuming it's a 2.0 hub, then you'll be hitting the EHCI stack on the
> host side, yes.
>

I already did use a hardware bus analyzer. I put the analyzer between the
hub and the device and I didn't see anything suspicous other then the host
freezes communication midway for no reason. I put the analyzer between the
host and hub but couldn't measure anything since my analyzer is full speed
only. That's when I noticed that disabling the enhanced controller to force
the hub into full speed solves the problem.

I don't think the problem is the hub since I see the same problem on two
different hubs from two difference manufactures.

And like I said, the firmware on the device is independent of hubs beings
used or not. Since my microcontroller is a PIC 18F2550 it's possible it's a
silicon bug in the SIE but I kind of doubt it.

Is the problem here that usbser.sys just isn't very supported by Microsoft
because it isn't high priority. Has anybody else tried connecting a full
speed usbser.sys device to a host via a high speed hub? Unforntinatly, their
arn't very many usbser devices and I don't own any to try.
From: Armageddon on 2 May 2008 13:31
Is it possible for me to upload the captures and the portman trace somewhere?
From: chris.aseltine on 2 May 2008 14:28
On May 2, 11:56 am, Armageddon <Armaged...(a)discussions.microsoft.com>
wrote:

> Is the problem here that usbser.sys just isn't very supported by Microsoft
> because it isn't high priority.

Look, no. Why are you blaming usbser.sys without any evidence? Why
do you think it's "not very supported" or "not a high priority"?

> Has anybody else tried connecting a full speed usbser.sys device to
> a host via a high speed hub?

Yes. I've personally done this hundreds, if not thousands of times
with no issues.
From: chris.aseltine on 4 May 2008 23:28
On May 2, 12:31 pm, Armageddon <Armaged...(a)discussions.microsoft.com>
wrote:

> Is it possible for me to upload the captures and the portman trace somewhere?

By the way if you're talking about a CATC trace then yes go post it
somewhere, I'd be interested in seeing it.
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