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: <ZyWv+BVp91xYr4UZ@dragon>
Date: Sat, 2 Nov 2024 12:52:08 +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 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.

Shawn

>  	status = "okay";
>  
>  	pca9450: pmic@25 {
> @@ -561,6 +562,7 @@ &i2c2 {
>  	pinctrl-1 = <&pinctrl_i2c2_gpio>;
>  	scl-gpios = <&gpio5 16 (GPIO_ACTIVE_HIGH | GPIO_OPEN_DRAIN)>;
>  	sda-gpios = <&gpio5 17 (GPIO_ACTIVE_HIGH | GPIO_OPEN_DRAIN)>;
> +	single-master;
>  	status = "disabled";
>  };
>  
> @@ -574,6 +576,7 @@ &i2c3 {
>  	pinctrl-1 = <&pinctrl_i2c3_gpio>;
>  	scl-gpios = <&gpio5 18 (GPIO_ACTIVE_HIGH | GPIO_OPEN_DRAIN)>;
>  	sda-gpios = <&gpio5 19 (GPIO_ACTIVE_HIGH | GPIO_OPEN_DRAIN)>;
> +	single-master;
>  };
>  
>  /* Verdin I2C_1 */
> @@ -584,6 +587,7 @@ &i2c4 {
>  	pinctrl-1 = <&pinctrl_i2c4_gpio>;
>  	scl-gpios = <&gpio5 20 (GPIO_ACTIVE_HIGH | GPIO_OPEN_DRAIN)>;
>  	sda-gpios = <&gpio5 21 (GPIO_ACTIVE_HIGH | GPIO_OPEN_DRAIN)>;
> +	single-master;
>  
>  	gpio_expander_21: gpio-expander@21 {
>  		compatible = "nxp,pcal6416";
> -- 
> 2.43.0
>