[PATCH] keyboard - was: Re: Linux 2.6.0-test4

[Andries Brouwer]

[I changed the subject to be slightly more indicative of contents.]

On Mon, Sep 01, 2003 at 06:01:25PM +0200, Ralf Hildebrandt wrote:
> * Chris Heath <chris@xxxxxxxxxxxxxx>:
> > > Aug 27 18:53:41 hummus2 kernel: atkbd.c: Unknown key (set 2, scancode 0x9d, on isa0060/serio0) pressed.
> > > Aug 27 19:15:14 hummus2 kernel: atkbd.c: Unknown key (set 2, scancode 0xb9, on isa0060/serio0) pressed.
> > > Aug 27 19:42:50 hummus2 kernel: atkbd.c: Unknown key (set 2, scancode 0x9d, on isa0060/serio0) pressed.
> > > Aug 28 10:14:14 hummus2 kernel: atkbd.c: Unknown key (set 2, scancode 0x9d, on isa0060/serio0) pressed.
> > > 
> > > Basically, CTRL was stuck. Even when I switched to X11.
> > 
> > Well, this completely baffles me.  I thought X11 maintains its own
> > keydown array.

It can do that only when it gets uncontaminated data.

> I applied your patch, and alas:
> 
> Sep  1 16:12:19 hummus2 kernel: atkbd.c: Unknown key (set 2, scancode 0xb9, on isa0060/serio0) pressed.
> Sep  1 16:12:19 hummus2 kernel: i8042 history: ae 9d e0 48 e0 c8 e0 38 56 d6 e0 b8 e0 b8 39 b9

I don't know why you say "alas". I read (two key releases, then)
press UpArrow, release UpArrow, RAlt, some key, release some key, release RAlt,
funny: again release RAlt, press space bar, release space bar.

So, nothing "Unknown" about this 0xb9 key - it is the spacebar release.

But i8042.c will do an unxlate when it thinks the key is down, so it
did not think so. But we saw the key down a moment ago. Apparently
the line

	set_bit(data | (i8042_last_e0 << 7), i8042_unxlate_seen);

did not set i8042_unxlate_seen for data = 0x39. And it is clear why:
The sequence e0 b8 e0 b8 is a repetition, the second e0 sets i8042_last_e0,
but after the second b8 we bail out without clearing i8042_last_e0 again.
*BUG*.

Conclusion: in the skipped double release case we must clear i8042_last_e0.

Andries

Vojtech: Note: 1 line should be added in i8042.c:i8042_interrupt().
[A stopgap - in fact all this i8042_unxlate_seen stuff should be ripped out.]

--- serio/i8042.c~      Sat Aug  9 22:16:42 2003
+++ serio/i8042.c       Tue Sep  2 03:09:12 2003
@@ -410,6 +410,7 @@
                        /* work around hardware that doubles key releases */
                        if (index == i8042_last_release) {
                                dbg("i8042 skipped double release (%d)\n", index);
+                               i8042_last_e0 = 0;
                                continue;
                        }
                        if (index == 0xaa || index == 0xb6)

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