linux-kernel - Re: [PATCH v2 1/3] dt-bindings: i2c: gpio: Add 'transition-delay-us' property

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Date: Mon, 3 Jun 2024 10:58:10 -0500
From: Rob Herring <robh@...nel.org>
To: Peter Rosin <peda@...ntia.se>
Cc: Bastien Curutchet <bastien.curutchet@...tlin.com>,
	Andi Shyti <andi.shyti@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Peter Korsgaard <peter.korsgaard@...co.com>,
	Wolfram Sang <wsa@...nel.org>, linux-i2c@...r.kernel.org,
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
	Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
	Herve Codina <herve.codina@...tlin.com>,
	Christopher Cordahi <christophercordahi@...ometrics.ca>
Subject: Re: [PATCH v2 1/3] dt-bindings: i2c: gpio: Add 'transition-delay-us'
 property

On Wed, May 29, 2024 at 02:13:37PM +0200, Peter Rosin wrote:
> Hi!
> 
> 2024-05-29 at 11:17, Bastien Curutchet wrote:
> > I2C MUXes described by the i2c-gpio-mux sometimes need a significant
> > amount of time to switch from a bus to another. When a new bus is
> > selected, the first I2C transfer can fail if it occurs too early. There
> > is no way to describe this transition delay that has to be waited before
> > starting the first I2C transfer.
> > 
> > Add a 'transition-delay-us' property that indicates the delay to be
> > respected before doing the first i2c transfer.
> 
> The io-channel-mux has a property with very similar intent named
> settle-time-us [1]. I think we should use the same name here.
> 
> [1] Documentation/devicetree/bindings/iio/multiplexer/io-channel-mux.yaml

Agreed. I knew we had something and went looking... I only checked the 
base mux and i2c mux bindings.

Rob