linux-kernel - Re: [PATCH v3 02/10] dt-bindings: pincfg-node: Add properties 'skew-delay-{in,out}put'

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Message-ID: <c2a0f301-ec5e-42d7-9df9-09a852a199ad@lunn.ch>
Date: Wed, 15 Oct 2025 18:37:32 +0200
From: Andrew Lunn <andrew@...n.ch>
To: Linus Walleij <linus.walleij@...aro.org>
Cc: Conor Dooley <conor@...nel.org>,
	Antonio Borneo <antonio.borneo@...s.st.com>,
	Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Maxime Coquelin <mcoquelin.stm32@...il.com>,
	Alexandre Torgue <alexandre.torgue@...s.st.com>,
	Bartosz Golaszewski <brgl@...ev.pl>, linux-gpio@...r.kernel.org,
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-stm32@...md-mailman.stormreply.com,
	linux-arm-kernel@...ts.infradead.org,
	Christophe Roullier <christophe.roullier@...s.st.com>,
	Fabien Dessenne <fabien.dessenne@...s.st.com>,
	Valentin Caron <valentin.caron@...s.st.com>
Subject: Re: [PATCH v3 02/10] dt-bindings: pincfg-node: Add properties
 'skew-delay-{in,out}put'

> I don't recall the reason for this way of defining things, but one reason
> could be that the skew-delay incurred by two inverters is very
> dependent on the production node of the silicon, and can be
> nanoseconds or picoseconds, these days mostly picoseconds.
> Example: Documentation/devicetree/bindings/net/adi,adin.yaml

I'm missing the big picture here, and i don't see an example of these
properties being used. However, since you reference an old networking
example, for RGMII delays....

adi,rx-internal-delay-ps should be deprecated, we now have the generic
rx-internal-delay-ps. The point about using -ps is however still
valid.

However, i would not like to see pinctl DT properties used in place of
rx-internal-delay-ps. How the Ethernet MAC driver implements
rx-internal-delay-ps is left open, so calling a pinctl API to set the
skew is fine by me. And if the real use case has nothing to do with
networking, then i don't care.

	    Andrew