Re: 2.6 input drivers FAQ

Vojtech Pavlik
2004-02-02T09:43:44Z

On Sun, Feb 01, 2004 at 04:14:52PM +0100, Andries Brouwer wrote:

> On Sun, Feb 01, 2004 at 02:50:01PM +0100, Vojtech Pavlik wrote:
>
> > Sorry. I was typing that from memory. I'll fix it. Btw, could you make
> > the kbd package accept scancodes in the 0x80-0xff range (same as e000 to
> > e07f), if it is not yet there? And how about scancodes in the
> > 0x100-0x1ff range? Will those work?
>
> What is needed for the 2.6 kernel is rather volatile
> (and maybe the present kernel version is not quite final yet).
> But setkeycodes does ioctl(fd,KDSETKEYCODE,&a) where
>
> a.keycode = atoi(argv[2]);
> a.scancode = strtol(argv[1], &ep, 16);
> if (a.scancode >= 0xe000) {
> a.scancode -= 0xe000;
> a.scancode += 128; /* some kernels needed +256 */
> }

I think this is fine. It keeps backwards compatibility with
people's old scripts and still it allows arbitrary scancodes.

> The 2.6.1 kernel is still very messy, with code
>
> if (atkbd->emul) {
> if (--atkbd->emul)
> goto out;
> code |= (atkbd->set != 3) ? 0x80 : 0x100;
> }
>
> where the representation of the e0 prefix depends on the current scancode mode.
> A bad idea.

Well, I think it's a bad idea to have the userspace tool know about the
e0 thing at all. It should be just opaque numbers to it.

I agree that the above code choosing between 0x80 and 0x100 is not very
nice, but it has two reasons:

0) e0+(00..7f) is the most common code for extra keys in set2,
while (80..df) is the most common code for extra keys in set3

1) it will work in old setkeycodes - although the values you'll
have to specify with set3 are rather nonsensical, you still
will be able to set extra keys on a set3 keyboard.

2) the scancode tables are much more compact.

I don't have a problem with swapping the set3 table, if setkeycodes
works reasonably now for scancodes above 128.

--
Vojtech Pavlik
SuSE Labs, SuSE CR