usb/149675: uftdi doesn't react to break properly

[Paul Thornton]

The following reply was made to PR usb/149675; it has been noted by GNATS.

From: Paul Thornton <prt at prt.org>
To: Hans Petter Selasky <hselasky at c2i.net>
Cc: freebsd-usb at freebsd.org, freebsd-gnats-submit at freebsd.org, 
 ed at freebsd.org
Subject: Re: usb/149675: uftdi doesn't react to break properly
Date: Sun, 15 Aug 2010 19:57:44 +0100

 Hi,
 
 Hans Petter Selasky wrote:
 > I believe the following patch will fix your problem. Please apply and rebuild 
 > kernel / ucom module.
 
 That has made a dramatic difference - things now look much better.
 Thank you very much for that.
 
 I'm still seeing a slight problem though.  In my test setup, I have a PC
 (Windows but that shouldn't matter!) running an appplication which
 transmits a break followed by the 513 data bytes - and this repeats
 continually at near line-rate at 250kbaud.
 
 Pre-patching, FreeBSD was unable to keep data byte 1 in location 1 at
 all - it appeared randomly wherever it happened to be due to the lack of
 break clearing the input buffer, and as the data dump of the buffer
 refreshed, the values moved around as the breaks were turning up as datab.
 
 After I've applied the patch, it starts off well - data byte 1 is in
 location 1, but every 5-10 seconds there is a shift by a byte suggesting
 that an extra byte has been received.  Is there any way that a break
 could still be creeping in to the data stream periodically?
 
 Under Linux, the code runs properly and there is no movement of the data
 bytes, so I'm reasonably confident that it isn't a bug of mine.
 
 Paul.