Messages in this thread |  | | | Date | Wed, 22 Aug 2001 20:09:59 +0200 | | From | (Gunther Mayer) | | Subject | Re: FYI PS/2 Mouse problems -- userland issue |
| |
Andries.Brouwer@cwi.nl wrote: > > > Armed with docs I was able to see just why our code > > is completely wrong for handling things like the ps/2 > > mouse being removed at runtime. > > Yes, or being added, to be more precise. But it will not be > easy to do it right. So many different ps2-like types of mouse. > There are heuristics, like the AA 00 that I gave last week or so. > (But not every ps2-mouse emits this sequence.)
Not every mouse controller lets this sequence thru ? (e.g. laptops with simultaneous stick +ps2 mouse)
A mouse not emitting this sequence would be broken. However you could easily recover by polling the mouse status every second. A newly-plugged mouse will have characteristic bit pattern.
> And one can keep track of the timing. But the fact that the length > of a packet is unknown (3, 4, 5, 8 bytes), and that in some modes > and relative positions arbitrary data is legal, makes it more or less > impossible to write code that is provably correct.
See above for a perfect solution.
> Also state machines have difficulties. Many types of mouse react > to special sequences of ordinary commands, and enter a non-ps2 mode.
See http://home.t-online.de/home/gunther.mayer/gm_psauxprint-0.01.c for a _dirty_ hack collecting info from various sources. This is the first linux tool to implement the PS2-PNP protocol (for identifying MS mice). - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
|  |