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Date: Tue, 23 Jan 2024 17:51:05 +0100
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Subject: Re: Implement per-key keyboard backlight as auxdisplay?
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To: Pavel Machek <pavel@ucw.cz>, Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: Jani Nikula <jani.nikula@linux.intel.com>,
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Am 19.01.24 um 23:14 schrieb Pavel Machek:
> Hi!
>
>>> And while I would personally hate it, you can imagine a use case where
>>> you'd like a keypress to have a visual effect around the key you
>>> pressed. A kind of force feedback, if you will. I don't actually know,
>>> and correct me if I'm wrong, but feels like implementing that outside of
>>> the input subsystem would be non-trivial.
>> Actually I think it does not belong to the input subsystem as it is,
>> where the goal is to deliver keystrokes and gestures to userspace.  The
>> "force feedback" kind of fits, but not really practical, again because
>> of lack of geometry info. It is also not really essential to be fully
>> and automatically handled by the kernel. So I think the best way is
>>> to
> So that's actually big question.
>
> If the common usage is "run bad apple demo on keyboard" than pretty
> clearly it should be display.
>
> If the common usage is "computer is asking yes/no question, so
> highlight yes and no buttons", then there are good arguments why input
> should handle that (as it does capslock led, for example).
The common usage is "make keyboard look flashy", for some a fixed color scheme 
is enough, other ones might probably enable one of the built in modes. Most 
people I think will be satisfied with these 2 options, albeit both of your 
suggestions sound cool.
>
> Actually I could imagine "real" use when shift / control /alt
> backlight would indicate sticky-shift keys for handicapped.
>
> It seems they are making mice with backlit buttons. If the main use is
> highlight this key whereever it is, then it should be input.
>
> But I suspect may use is just fancy colors and it should be display.
>
> Best regards,
> 								Pavel