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

From: Rob Herring <robh@kernel.org>
To: Nicolas Frattaroli <nicolas.frattaroli@collabora.com>
Cc: Krzysztof Kozlowski <krzk@kernel.org>,
	Dmitry Torokhov <dmitry.torokhov@gmail.com>,
	Krzysztof Kozlowski <krzk+dt@kernel.org>,
	Conor Dooley <conor+dt@kernel.org>,
	Alexandre Belloni <alexandre.belloni@bootlin.com>,
	Heiko Stuebner <heiko@sntech.de>,
	kernel@collabora.com, linux-input@vger.kernel.org,
	devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-rockchip@lists.infradead.org
Subject: Re: [PATCH v2 1/4] dt-bindings: input: adc-keys: allow linux,input-type property
Date: Wed, 17 Dec 2025 07:34:40 -0600	[thread overview]
Message-ID: <20251217133440.GA724723-robh@kernel.org> (raw)
In-Reply-To: <6778765.lOV4Wx5bFT@workhorse>

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