> I have a USB class driver that is working fine on some machines and
not others and I am not sure why.
Simple checks:
Is your “Driver Interface GUID” unique?
Test a different USB port on a machines where it fails.
Check if the problems go away if you add a USB hub between PC and device.
From our experience, some USB2 host I/Fs seem subtly broken.
(Is it the chip? A PCB routing/wiring issue? We can’t say!)
In all scenarios everything works fine with USB1.1, but then using
USB2.0 people get weird problems:
In some cases just plugging in an cable (no device) at a different(!)
USB port causes transfer problems.
In one case a second USB2 device (e.g. USB-“NIC”) caused a problem.
In one report, a user using a laptop/docking station reported that all
works fine for about half an hour, then our USB device is “lost”.
Plugging it in directly at the laptop works fine for days.
In one case, a KVM switch USB cable plugged at a different(!) USB port
than our device was exchanged against a same-length(!) external cable,
then the problems vanished.
Unfortunately (so far) we did not get hold of a system where we can
reproduce the problem, to check it out with an external USB probe.
USB2 with 480Mbit/s is already in R/F range. Let’s look forward to USB3.
I know very little at all about USB (any version), but just from my
experience as a regular old user of removable usb devices, it does indeed
seem that there are some amazingly crappy ones out there.
mm
-----Original Message-----
From: xxxxx@lists.osr.com
[mailto:xxxxx@lists.osr.com] On Behalf Of Hagen Patzke
Sent: Friday, September 10, 2010 4:36 AM
To: Windows System Software Devs Interest List
Subject: [ntdev] [USB problems] Different machines doing different things
I have a USB class driver that is working fine on some machines and
not others and I am not sure why.
Simple checks:
Is your “Driver Interface GUID” unique?
Test a different USB port on a machines where it fails.
Check if the problems go away if you add a USB hub between PC and device.
From our experience, some USB2 host I/Fs seem subtly broken.
(Is it the chip? A PCB routing/wiring issue? We can’t say!) In all
scenarios everything works fine with USB1.1, but then using
USB2.0 people get weird problems:
In some cases just plugging in an cable (no device) at a different(!) USB
port causes transfer problems.
In one case a second USB2 device (e.g. USB-“NIC”) caused a problem.
In one report, a user using a laptop/docking station reported that all
works fine for about half an hour, then our USB device is “lost”.
Plugging it in directly at the laptop works fine for days.
In one case, a KVM switch USB cable plugged at a different(!) USB port
than our device was exchanged against a same-length(!) external cable, then
the problems vanished.
Unfortunately (so far) we did not get hold of a system where we can
reproduce the problem, to check it out with an external USB probe.
USB2 with 480Mbit/s is already in R/F range. Let’s look forward to USB3.