Re: [PATCH v2 1/4] dt-bindings: input: adc-keys: allow linux,input-type property

Rob Herring
2025-12-17T13:34:57Z

On Wed, Dec 17, 2025 at 01:57:46PM +0100, Nicolas Frattaroli wrote:
> On Wednesday, 17 December 2025 09:31:15 Central European Standard Time Krzysztof Kozlowski wrote:
> > On Mon, Dec 15, 2025 at 01:29:29PM +0100, Nicolas Frattaroli wrote:
> > > adc-keys, unlike gpio-keys, does not allow linux,input-type as a valid
> > > property. This makes it impossible to model devices that have ADC inputs
> > > that should generate switch events.
> >
> > The solution is to use unevaluatedProps instead, which also allows
> > dropping other properties.
> >
> > Best regards,
> > Krzysztof
> >
> >
>
> Hi Krzysztof,
>
> to understand the motivation behind this suggestion correctly:
> are the "linux," vendor prefixed properties, especially with regards
> to key codes, generally a bit of a thorn in the side of DT bindings
> maintainers?

Not really. Most have existed for decades. New ones get extra scrutiny
and often end up dropping the linux prefix.

> I'd imagine so since they technically tie the DT to a specific OS
> kernel (though of course, others are free to translate those key
> codes). And the whole idea of configuring which code is emitted
> from something is basically abusing DT for configuring software
> rather than describing hardware.
>
> I'm mainly interested because this is a thought that has been in
> the back of my mind for a while now, and I'm curious if the DT
> binding maintainers happen to have arrived at the same impassé,
> where linux,input-type et al abuse the DT model for something we
> would tell any other vendor not to abuse it for, but no better
> solution exists right now to achieve the same thing.

Not sure what the BSDs do here. It's never come up that I remember. Best
I can tell is they just make it a userspace problem. So every possible
keyboard needs a keymap file. Though I'm not sure how that would work
with GPIO keys as you don't really have a scan code.

Rob