ucom/uftdi dropping bytes, with debug logs

[Geoffrey Mainland]

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...

Thanks,
Geoff