M. Warner Losh wrote: > In message: <[EMAIL PROTECTED]> > Geoffrey Mainland <[EMAIL PROTECTED]> writes: > : I've been trying to debug a problem with a ftdi-based serial device > : where bytes are being dropped. The device is a Moteiv tmote sky with a > : 8U232BM chip. Reprogramming this device always fails due to dropped > : bytes. I eventually set up a VMWare image (under Windows) to make > : debugging a bit easier, as I was crashing my machine often, and lo and > : behold the problem went away! It looks like VMWare's USB interface is > : buffering the data, so the FreeBSD driver works just fine under VMWare! > : > : I turned on debugging in the ucom and uftdi drivers. Logs of the > : transfers under both VMWare and a native environment are posted at: > : > : http://www.apeiron.net/~mainland/uftdi/vmware-log.txt.gz > : > : and > : > : http://www.apeiron.net/~mainland/uftdi/native-log.txt.gz > : > : This is under a recent 6.1 stable (for both "machines"). > : > : As you can see, the VMWare transfer manages to read a lot more data... > : > : How do I go about finding the real problem and fixing it? I know nothing > : about the FreeBSD USB stack... > > I have similar problems with FTDI, but every time that I think I've > found one, I discover that I have a second 'tip' running that's eating > some characters :-( Are you sure that this isn't happening? I know > it is a "rookie" mistake, but I recently wasted a day on it, and I'm > no rookie :-). > > Anyway, I've also seen other weird behavior with my ftdi dongle, but > I've never been able to reproduce it well enough to try to fix the > problem... > > Warner
Wow, thanks for the quick response! Yes, I'm sure no second 'tip' is running. In any case, wouldn't the reads from the second 'tip' still be logged? :) The fact that this runs fine under VMWare makes me strongly suspect a timing issue that is fixed by some sort of buffering at the VMWare level. Where should I start to look to hack something in to test this? The ucom driver seems to be setting up the read transfers that don't complete on time. Geoff _______________________________________________ [email protected] mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-usb To unsubscribe, send any mail to "[EMAIL PROTECTED]"
