linux-kernel - Re: [PATCH v1 1/2] arm64: dts: imx8mm-verdin: add single-master property to all i2c nodes

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Message-ID: <Zyc6pVCVLW+s4Bi9@dragon>
Date: Sun, 3 Nov 2024 16:56:05 +0800
From: Shawn Guo <shawnguo2@...h.net>
To: Stefan Eichenberger <eichest@...il.com>
Cc: robh@...nel.org, krzk+dt@...nel.org, conor+dt@...nel.org,
	shawnguo@...nel.org, s.hauer@...gutronix.de, kernel@...gutronix.de,
	festevam@...il.com, francesco.dolcini@...adex.com,
	devicetree@...r.kernel.org, imx@...ts.linux.dev,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	Stefan Eichenberger <stefan.eichenberger@...adex.com>
Subject: Re: [PATCH v1 1/2] arm64: dts: imx8mm-verdin: add single-master
 property to all i2c nodes

On Sat, Nov 02, 2024 at 03:31:56PM +0100, Stefan Eichenberger wrote:
> Hi Shawn,
> 
> On Sat, Nov 02, 2024 at 12:52:08PM +0800, Shawn Guo wrote:
> > On Fri, Oct 25, 2024 at 11:58:02AM +0200, Stefan Eichenberger wrote:
> > > From: Stefan Eichenberger <stefan.eichenberger@...adex.com>
> > > 
> > > By default we expect all i2c nodes to be single-master, we do not have
> > > any module or carrier board that uses multi-master mode on any i2c
> > > controller. With this property set, we benefit from optimisations made
> > > exclusively for single-masters.
> > > 
> > > Signed-off-by: Stefan Eichenberger <stefan.eichenberger@...adex.com>
> > > ---
> > >  arch/arm64/boot/dts/freescale/imx8mm-verdin.dtsi | 4 ++++
> > >  1 file changed, 4 insertions(+)
> > > 
> > > diff --git a/arch/arm64/boot/dts/freescale/imx8mm-verdin.dtsi b/arch/arm64/boot/dts/freescale/imx8mm-verdin.dtsi
> > > index 5fa3959141911..95d5d2333ca1e 100644
> > > --- a/arch/arm64/boot/dts/freescale/imx8mm-verdin.dtsi
> > > +++ b/arch/arm64/boot/dts/freescale/imx8mm-verdin.dtsi
> > > @@ -367,6 +367,7 @@ &i2c1 {
> > >  	pinctrl-1 = <&pinctrl_i2c1_gpio>;
> > >  	scl-gpios = <&gpio5 14 (GPIO_ACTIVE_HIGH | GPIO_OPEN_DRAIN)>;
> > >  	sda-gpios = <&gpio5 15 (GPIO_ACTIVE_HIGH | GPIO_OPEN_DRAIN)>;
> > > +	single-master;
> > 
> > Hmm, I do not see this property is documented in i2c-imx bindings.
> 
> According to the discussion we had in this thread
> https://lore.kernel.org/linux-i2c/2bbddaxyjkxfmlgmq3yqcbzo7dsb2pq5bvdatk2y4ig4iintkt@35btqkdv7sy3/
> it is not necessary to have the property documentation in the i2c-imx
> binding because it is already documented in the dt-schema:
> https://github.com/devicetree-org/dt-schema/blob/main/dtschema/schemas/i2c/i2c-controller.yaml

Ah, thanks for the info!

Shawn