16850 automatic RTS/CTS

16850 automatic RTS/CTS

[Guennadi Liakhovetski]

Hello

As of 2.5.6 there is some support in the serial driver for the 16850
automatic hardware handshake feature, in particular the automatic CTS is
enabled, but not the automatic RTS. Nor are the hysteresis levels set.
Why? I tried enabling all these features, it helps a good deal improving
the reliability of the data transfer, but still, at high baud-rates
(460800, 921600) and in the presence of user-space load data can be
overwritten in the driver's buffer. Why isn't this checked?

Thanks
Guennadi
---------------------------------
Guennadi Liakhovetski, Ph.D.
DSA Daten- und Systemtechnik GmbH
Pascalstr. 28
D-52076 Aachen
Germany

RE: 16850 automatic RTS/CTS

[Ed Vance]

On Wed, May 08, 2002, Guennadi Liakhovetski wrote:
> 
> As of 2.5.6 there is some support in the serial driver for the 
> 16850 automatic hardware handshake feature, in particular the 
> automatic CTS is enabled, but not the automatic RTS. Nor are 
> the hysteresis levels set. Why? I tried enabling all these 
> features, it helps a good deal improving the reliability of the 
> data transfer, but still, at high baud-rates (460800, 921600) 
> and in the presence of user-space load data can be overwritten 
> in the driver's buffer. Why isn't this checked? 

Hi Guennadi,

Like so many other good ideas, this feature support is not already there
simply because nobody has submitted a patch for it, yet. (and
followed-up/lobbied with sufficient tenacity and grace) 

Also, be aware that there is in progress a rewrite of the serial driver
subsystem for 2.5. See Russell King's entry in the maintainers list. 

I'm only on the 2.4 side, but I would like to see a tested patch against
either 2.5 or 2.4 for fixup of 16850 support. Since you have the 16850
hardware (and I don't), please consider creating a patch to serial.c and
friends that adds this feature support and posting it for discussion to 
linux-serial@vger.kernel.org. Put enough comments at the top so anyone with
the datasheet can understand your intent. 

Thanks,
Ed

---------------------------------------------------------------- 
Ed Vance              edv@macrolink.com
Macrolink, Inc.       1500 N. Kellogg Dr  Anaheim, CA  92807
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Re: 16850 automatic RTS/CTS

[Russell King]

On Wed, May 08, 2002 at 09:58:54AM -0700, Ed Vance wrote:
> Like so many other good ideas, this feature support is not already there
> simply because nobody has submitted a patch for it, yet. (and
> followed-up/lobbied with sufficient tenacity and grace) 

Guennadi's been playing around with the device trying to get it to work...
He's made progress and I'm dealing with it atm.

-- 
Russell King (rmk@arm.linux.org.uk)                The developer of ARM Linux
             http://www.arm.linux.org.uk/personal/aboutme.html