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SubjectRe: keyboard scancodes
On Sun, Dec 12, 1999 at 08:21:13PM +0000, Derek Fawcus wrote:

> On Sat, Dec 11, 1999 at 10:12:36AM +0100, Vojtech Pavlik wrote:
> >
> > All i8042's I've tested (and I've tested a lot of them) support
> > switching the AT->XT conversion off. Most keyboards (not all,
> > but that isn't too big a problem) support switching the AT emulation
> > off, too.
>
> Agreed on the i8042 translation, a few years ago I tested this in
> embedded PC environments, and every board I found allowed they keyboard
> controller translation to be turned off. This would increase the amount
> of data sent (f0 prefix for down code if I remember correctly), but
> subsequent translation is a hell of a lot simpler.

The amount of data going over the wire is actually the same, only the
amount of data read from the i8042 increases, and that isn't a problem.

More on the translation: Switching it off also makes the Focus9000
keyboard behave reasonably, because keys with codes over 0x80 aren't
a problem anymore. The old driver has to have terrible kludges in it
to allow presing and releasing keys with codes over 0x80.

> If by the keyboard switching, you're referring to the scan set it
> supplies (set1/set2/set3), then there is a problem. For some of the
> keyboards I tested, changing out of the normal set (set2 I think)
> would crash the keyboard. The only way to then recover was to power
> cycle the keyboard.

My current keyboard driver in the input patches doesn't attempt to
switch out of the default set2 unless a command option is passed to it,
telling it to attempt set3, because that one is better.

Many keyboards have problems with set3 implementation, because windows
doesn't use that and it is not tested by the manufacturers.

--
Vojtech Pavlik
SuSE Labs

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