Re: tcdrain / TCSBRK / wait_until_sent delay

[Russell King <rmk@arm.linux.org.uk>]

On Mon, May 09, 2005 at 10:16:03AM +0200, Tosoni wrote:
> - Then Mr Russel King suggested to redesign a complete "line discipline"

Please do me the reasonable curtesy of spelling my name correctly.

> just to handle the missing RTS feature. I must note that such "line
> discipline" would duplicate completely the existing default line discipline
> except for the RTS_TOGGLE ioctl.

Interestingly, I've reviewed our discussions back in December, and
they aren't exactly how you recollect them to be.  I gave you the
historical position, and suggested both a possible way forward and
someone else for you to talk to about this.

It also appears that you continued to press for _your_ original
implementation, justifying it against the historical position (both
of which I'd already suggested weren't suitable.)

Maybe I didn't explain clearly enough why your implementation wasn't
suitable.  Adding an IOCTL for RS485 RTS style vs conventional RTS
style causes problems.  Consider what happens when:

1. we get a third (and there are more than two) flow control styles.
2. the port is closed and something else opens it which wants standard
   flow control. (or even an overlapping open/close.)

I have also suggested to a third party about adding a feature by which
the flow control method could be changed between several different
settings, preferably via the existing control implmentation - termios.
This should resolve both of the above.

Unfortunately, that also went by un-noticed and as such hasn't progressed.

Therefore, there has been no progress on different flow control styles.

-- 
Russell King
 Linux kernel    2.6 ARM Linux   - http://www.arm.linux.org.uk/
 maintainer of:  2.6 Serial core