Alan Stern писал 25.09.2012 19:57:
On Tue, 25 Sep 2012, Greg KH wrote:
On Tue, Sep 25, 2012 at 04:57:43PM +0400, Andrew wrote:
> Uwe Bonnes писал 25.09.2012 12:46:
> >>>>>>"Andrew" == Andrew <andrew@xxxxxxxxxx> writes:
> >
> > Andrew> This is seen on widely used ftdi ft232rl chips.
> >Setting the
> > Andrew> parity to something like 'even' results in occasional
> >framing
> > Andrew> errors when transmitting data.
> >
> > Andrew> Relevant timing diagrams from the logic analyzer are
> >attached to
> > Andrew> this bug:
> >https://bugzilla.kernel.org/show_bug.cgi?id=47921
> >
> >Is this a driver or a hardware thing?
>
> I think that this is a driver problem, since windows drivers do
not
> produce any framing errors.
> I stumbled upon this while reversing the STC microcontroller ISP
> protocol that happen to use 'even' parity.
> I can send in more timing diagrams both from windows and linux
hosts
> to compare.
I don't see how the ftdi device can change the timings of the
signals by
the USB side at all, do you? That implies that it couldn't be the
driver as it has no control over this type of thing.
Or am I missing something from the device spec somewhere?
It might be a good idea to compare a usbmon trace with an equivalent
record from a Windows system.
Alan Stern
I had a quick look what I have in the junk and found an ft2232 mini
module.
I'm afraid these are the only ftdi chips I have around right now.
I'll give them both a try and post logic analyzer dumps and
and usbsnoop logs from both windows and linux machines asap.
P.S. Can anyone link the protocol spec? I haven't found a thing
regarding
the usb protocol in the official datasheet, that kind of limits what I
can
possibly try out myself.
--
Regards,
Andrew
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