Caps lock XOR on multiple keyboards?

Caps lock XOR on multiple keyboards?

[George Spelvin]

(Moving to linux-input.)

I happen to have both a PS/2 and USB keyboard plugged, in, but was
noticing that the caps lock key seemed inverted.  When the LED was off,
I got all caps (unless I used shift), while when it was on I got normal
lower-case letters.

This quite confused me, until I looked over and saw that someone had
hit caps lock on the PS/2.

Experimenting, it seems that each keyboard has its own caps lock LED
state, and the XOR of the two controls the case of the letters.

The corresponding shift keys have a shared logical state which depends
on who last had a transition.  Holding down left-shift on one can be
cancelled by pressing and releasing left-shift on the other.  (But
left & right shift are tracked separately.)

It would make more sense if each keyboard's caps lock LED controlled
the effect on its keys.  Either give each keyboard a completely separate
caps lock state, or toggle both LEDs when either caps lock is pressed.

Perhaps the answer is "It's too much work to fix; stop doing something
so stupid", but I thought I'd at least mention it.

(Er... it appears that my XOR description was incomplete.  I now have
the keyboard system in a state where *one* caps lock LED has to be on
to get normal lower-case letters.  I was playing with down1/down2/up1/up2
combinations, but I'm not quite sure what happened...)

Re: Caps lock XOR on multiple keyboards?

[Dmitry Torokhov]

Hi George,

On Monday, December 03, 2012 07:01:01 PM George Spelvin wrote:
> (Moving to linux-input.)
> 
> I happen to have both a PS/2 and USB keyboard plugged, in, but was
> noticing that the caps lock key seemed inverted.  When the LED was off,
> I got all caps (unless I used shift), while when it was on I got normal
> lower-case letters.
> 
> This quite confused me, until I looked over and saw that someone had
> hit caps lock on the PS/2.
> 
> Experimenting, it seems that each keyboard has its own caps lock LED
> state, and the XOR of the two controls the case of the letters.
> 
> The corresponding shift keys have a shared logical state which depends
> on who last had a transition.  Holding down left-shift on one can be
> cancelled by pressing and releasing left-shift on the other.  (But
> left & right shift are tracked separately.)
> 
> It would make more sense if each keyboard's caps lock LED controlled
> the effect on its keys.

LEDs do not control state, state should control LEDs.

> Either give each keyboard a completely separate
> caps lock state, or toggle both LEDs when either caps lock is pressed.

When in console (i.e. not X) then all keyboard's LEDs and state should be 
synced together. I.e. when pressing CapsLock on one keyboard both keyboards 
CapsLock LEDs should come on or off and the register should be the same.

This is known to be broken in X (and should be reported [again] there) but
if you can provide scenario to break it in VT I'd love to know it.

> 
> Perhaps the answer is "It's too much work to fix; stop doing something
> so stupid", but I thought I'd at least mention it.

No, it is not stupid at all.

Thanks.

-- 
Dmitrys

Re: Caps lock XOR on multiple keyboards?

[George Spelvin]

> This is known to be broken in X (and should be reported [again] there) but
> if you can provide scenario to break it in VT I'd love to know it.

Ding ding ding, you win the prize!  Yes, I was in X at the time.
Me dumbshit; I should have realized that this was relevant and mentioned
it.  My apologies.

The bad part is now I have to figure out which layer of what
to point the finger at.  :-(

Sorry for the noise.

Re: Caps lock XOR on multiple keyboards?

[Pavel Machek]

Hi!
On Mon 2012-12-03 23:58:48, Alan Cox wrote:
> On 3 Dec 2012 16:19:11 -0500
> "George Spelvin" <linux@horizon.com> wrote:
> 
> > (Not sure who owns this; Cc: to the last few people to touch
> > drivers/tty/vt/keyboard.c.)
> 
> linux-input is probably the best place to discuss this

Added few more ccs. Yes, I see that too, in kernels such as debian
2.6.32. It may be even older than that, but I was not using docking
heavily in the old days.

Symptoms for me are that pretty often capslock LED will start show
opposite of true capslock state. I normally use X these days.

(Other problem seems to be that keyboard LEDs are not updated on
keyboard hotplug.)

There is patch to drive keyboard LEDs through LED subsystem, perhaps
that would be good idea?

									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

Re: Caps lock XOR on multiple keyboards?

[Pavel Machek]

On Sun 2013-03-24 11:30:18, Pavel Machek wrote:
> Hi!
> On Mon 2012-12-03 23:58:48, Alan Cox wrote:
> > On 3 Dec 2012 16:19:11 -0500
> > "George Spelvin" <linux@horizon.com> wrote:
> > 
> > > (Not sure who owns this; Cc: to the last few people to touch
> > > drivers/tty/vt/keyboard.c.)
> > 
> > linux-input is probably the best place to discuss this
> 
> Added few more ccs. Yes, I see that too, in kernels such as debian
> 2.6.32. It may be even older than that, but I was not using docking
> heavily in the old days.
> 
> Symptoms for me are that pretty often capslock LED will start show
> opposite of true capslock state. I normally use X these days.

Ok... so it is:

Each capslock key only controls the local LED, but affects global
state.

So I turn on capslock on PS/2 keyboard its led is on. But I type on
USB keyboard, its capslock led is off, but I type in all caps. Oops.

								Pavel 
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

Re: Caps lock XOR on multiple keyboards?

[Samuel Thibault]

Hello,

I can confirm that things go fine on the Linux console.  There is just
one state, which is shown on all keyboards.  This is really a bug in
Xorg, please report the issue there.

Pavel Machek, le Sun 24 Mar 2013 11:30:18 +0100, a écrit :
> There is patch to drive keyboard LEDs through LED subsystem, perhaps
> that would be good idea?

My patch won't fix the issue for Xorg, but it'd still be a good thing to
at last apply it :)

Samuel
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Re: Caps lock XOR on multiple keyboards?

[Peter Korsgaard]

>>>>> "Samuel" == Samuel Thibault <samuel.thibault@ens-lyon.org> writes:

 Samuel> Pavel Machek, le Sun 24 Mar 2013 11:30:18 +0100, a écrit :
 >> There is patch to drive keyboard LEDs through LED subsystem, perhaps
 >> that would be good idea?

 Samuel> My patch won't fix the issue for Xorg, but it'd still be a good
 Samuel> thing to at last apply it :)

Agreed.

-- 
Bye, Peter Korsgaard