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

[Hans Petter Selasky]

On Sunday 15 August 2010 20:57:44 Paul Thornton wrote:
> 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.

I guess you will have to turn on ucom and uftdi debugging knobs under 
hw.usb.xxx to figure that out. USB is just forwarding what it gets from the 
hardware.

--HPS