Pelle Windestam wrote:
> Jim Paris wrote:
> >If you want to really dive in deep, you can modprobe the usbmon
> >module, use wireshark to get a full dump of the bus traffic, and
> >compare the two cases to see what might be missing in the libftdi-only
> >case.
>
> I did some logging with usbmon yesterday, and I have tried to make
> some sense of it. I have never looked at usb bus traffic before, so
> it is slightly confusing. What I could make out of it however is
> that in the working scenario, I can see the frames I send out and
> the response from my external device.
>
> In the non-working case I can see the data going out as a "URB_BULK
> out" package, and in most cases I receive a "URB_BULK in" packet
> with the same data as I sent out, usually split over several
> packages (I get this package in the working case as well), but never
> a response from the external device.
I was thinking more of the control packets that get sent before the
bulk transfers. We know that libftdi works as long as the kernel
driver did "something" to the device first, so the usbmon trace would
be one way to see what the missing libftdi initialization was, if
there's a problem there.
If you want to send me the two captures off-list I can try to take a
look.
-jim
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