Re: Implement per-key keyboard backlight as auxdisplay?

Pavel Machek
2024-01-18T17:45:39Z

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Hi!

> We have an upcoming device that has a per-key keyboard backlight, but does
> the control completely via a wmi/acpi interface. So no usable hidraw here
> for a potential userspace driver implementation ...
>
> So a quick summary for the ideas floating in this thread so far:
>
> 1. Expand leds interface allowing arbitrary modes with semi arbitrary
> optional attributes:

>     - Con:
>
>         - Violates the simplicity paradigm of the leds interface (e.g. with
> this one leds entry controls possible multiple leds)

Let's not do this.

> 2. Implement per-key keyboards as auxdisplay
>
>     - Pro:
>
>         - Already has a concept for led positions
>
>         - Is conceptually closer to "multiple leds forming a singular entity"
>
>     - Con:
>
>         - No preexisting UPower support
>
>         - No concept for special hardware lightning modes
>
>         - No support for arbitrary led outlines yet (e.g. ISO style enter-key)

Please do this one.

> 3. Implement in input subsystem
>
>     - Pro:
>
>         - Preexisting concept for keys and key purpose
>
>     - Con:
>
>         - Not in scope for subsystem
>
>         - No other preexisting light infrastructure

Or negotiate with input people to do this.

> 4. Implement a simple leds driver only supporting a small subset of the
> capabilities and make it disable-able for a userspace driver to take over

No. Kernel should abstract this away.

Best regards,
Pavel
--
People of Russia, stop Putin before his war on Ukraine escalates.

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