Re: USB device detection via query registry information
- From: "Doron Holan [MSFT]" <doronh@xxxxxxxxxxxxxxxxxxxx>
- Date: Wed, 3 Sep 2008 14:28:37 -0700
WHQL is not a 100% measure of quality across an entire driver, rather it is a set of tests specifically designed to test very specific parts of a driver. why is msft reponsible for the crud that FTDI wrote? serenum and sermouse work as expected on the in box version of serial, it correctly enforces exclusivity to the port
d
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"Ben Voigt [C++ MVP]" <rbv@xxxxxxxxxxxxx> wrote in message news:ORV1HEgDJHA.528@xxxxxxxxxxxxxxxxxxxxxxx
Doron Holan [MSFT] wrote:sermouse opens the underlying serial port just like an app does. are
you seeing this with the in box serial.sys driver? or with a 3rd
party driver like one for a usb->serial device?
It's USB/serial converter, from FTDI (doesn't use communication device class). Their driver is WHQL. I wouldn't doubt that their driver is causing the problem since one version ago simply opening a device on a multicore system was BSOD within 10 seconds. Which doesn't totally absolve MS of responsibility. What's the good of WHQL if even buggy drivers can be approved?
serenum and sermouse are out-of-the-box XP as far as I can determine.
I should be able to load the problem configuration in a kernel debugger and have debug output from my userland application showing the result of the device interface open. If someone could advise me on how to enable tracing of serenum/sermouse or where to set a breakpoint, I could determine the order of events definitively.
"Ben Voigt [C++ MVP]" <rbv@xxxxxxxxxxxxx> wrote in message
news:O7l7AheDJHA.2292@xxxxxxxxxxxxxxxxxxxxxxx
Doron Holan [MSFT] wrote:for serial mouse detection, there is a window between detection and
driver load. serenum opens the port, detects the device, closes the
port and then enumerates the child device. the child device stack
will then attempt to open the port again. in between the serenum
close and the child stack open, your app can easily open the port.
if you do open the port in this window, the serial mouse driver will
fail to open the port and fail the pnp start
What I observed was:
My application had an open handle to the port.
AND
The serial mouse driver was spamming my system with pointer motion
and mouse clicks.
I cannot tell you with certainty which opened the port first, I just
understand that it should not be possible for both sermouse and a
user-mode application to have the port open no matter which goes
first. My application opened the port using the device interface
path received through WM_DEVICECHANGE and SetupDi* queries. Is
there any chance that the way file sharing and exclusivity is
enforced might this and the DosDevices link these as separate? Although, I should think that serenum and sermouse should also use
the raw interface path.
d
"Ben Voigt [C++ MVP]" <rbv@xxxxxxxxxxxxx> wrote in message
news:eGpGZ4VCJHA.2480@xxxxxxxxxxxxxxxxxxxxxxx
"Doron Holan [MSFT]" <doronh@xxxxxxxxxxxxxxxxxxxx> wrote in message
news:#erdV4SCJHA.2060@xxxxxxxxxxxxxxxxxxxxxxx
i agree with chris, i have never heard of this happening
I don't remember for sure, but I think I observed this behavior
fairly frequently when the device was surprise removed and
reinserted (i.e. bus reset) all before WM_DEVICECHANGE processing
for the original insertion completed.
Of course, it could be the communication protocol with the device
itself broke down and never reached the ready state. There's a lot
of additional testing needed on the system.
I am quite sure about the mouse issue though. I was able to open a
handle to the com port and Windows also decided to detect a mouse.
This shouldn't be possible, either Windows should detect the mouse
first and my CreateFile fails or else my CreateFile succeeds first
and then SERENUM can't listen for data to run its heuristic mouse
detection. There's another problem where disabling the device in
the WM_DEVICECHANGE handler reliably and reproducibly shuts down
the entire Windows Device Manager / Plug and Play system. (This
was one attempted workaround for the aforementioned false mouse
detection). This is why I say WM_DEVICECHANGE isn't a 100% reliable method for
determining when the device is ready for use.
d
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<chris.aseltine@xxxxxxxxx> wrote in message
news:1cc364ba-649e-4bae-b37b-925de49852a9@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
On Aug 28, 8:13 am, "Ben Voigt [C++ MVP]" <r...@xxxxxxxxxxxxx>
wrote:
Next, WM_DEVICECHANGE is quite unreliable. It is necessary to
also poll the
list of ports (of course using SetupDi* functions, not registry
access, and
test the device state) because the user-mode WM_DEVICECHANGE
handler needs
an arbitrary amount of time to complete (by definition,
user-mode processes
can be blocked by higher-priority user or kernel tasks) and some
device insertion notifications are not delivered in this case.
I've never heard of or observed this phenomenon, and your
explanation for why you think it happens is nebulous at best. Do
you have a reproducible example?
.
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