cvs commit: src/sys/isa psm.c

[Eivind Eklund]

On Thu, Dec 11, 2003 at 03:28:11AM -0800, Alfred Perlstein wrote:
>   Log:
>   Significantly reduce the "jitter" that is typical for PS/2 mice
>   when using a KVM.
[...]
>   
>   The actual solution that appears to offer the best clamping of
>   jitter is to buffer the mouse packets if we've not seen mouse
>   activity for more than .5 seconds.  Then waiting to flush that data
>   for 1/20th of a second.  If within that 20th of a second we get any
>   packets that do fail the weak test we drop the entire queue and
>   back off accepting data from the mouse for 2 seconds and then repeat
>   the whole deal.

Have you tested this with enough high speed interactive games?  50ms 
(1/20s) is three to four frames, and quite a lot of delaying input.  
There are a number of types of games that require faster response than 
this.  I'm not entirely sure how it influences most mouse-run games - I 
know that at least some 2D fighting games with joystick absolutely 
required 1-frame (20ms) response on 50Hz displays.   

[...]
>   Lastly I'd like to note that my experience with Windows shows me that
>   somehow the Microsoft PS/2 driver typically avoids this problem, but
>   that may only be possible when running the mouse in a dumb-ed down PS/2
>   mode that Belkin recommends on their site.

It'd be interesting to know what they do.


>   Revision  Changes    Path
>   1.63      +256 -110  src/sys/isa/psm.c

Eivind.