linux-kernel - Re: [PATCH v2 2/3] arm64: dts: marvell: AC5: use I2C unstuck function

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Date:   Thu, 19 Oct 2023 16:40:05 +0200
From:   Gregory CLEMENT <gregory.clement@...tlin.com>
To:     Chris Packham <chris.packham@...iedtelesis.co.nz>,
        andi.shyti@...nel.org, robh+dt@...nel.org,
        krzysztof.kozlowski+dt@...aro.org, conor+dt@...nel.org,
        pierre.gondois@....com
Cc:     linux-i2c@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Chris Packham <chris.packham@...iedtelesis.co.nz>
Subject: Re: [PATCH v2 2/3] arm64: dts: marvell: AC5: use I2C unstuck function

Hello Chris,

> The AC5 SoC supports using a controller based I2C unstuck function for
> recovery. Use this instead of the generic GPIO recovery.
>
> Signed-off-by: Chris Packham <chris.packham@...iedtelesis.co.nz>
> ---
>  arch/arm64/boot/dts/marvell/ac5-98dx25xx.dtsi | 14 ++++----------
>  1 file changed, 4 insertions(+), 10 deletions(-)
>
> diff --git a/arch/arm64/boot/dts/marvell/ac5-98dx25xx.dtsi b/arch/arm64/boot/dts/marvell/ac5-98dx25xx.dtsi
> index c9ce1010c415..e52d3c3496d5 100644
> --- a/arch/arm64/boot/dts/marvell/ac5-98dx25xx.dtsi
> +++ b/arch/arm64/boot/dts/marvell/ac5-98dx25xx.dtsi
> @@ -137,7 +137,7 @@ mdio: mdio@...04 {
>  
>  			i2c0: i2c@...00{
>  				compatible = "marvell,mv78230-i2c";
> -				reg = <0x11000 0x20>;
> +				reg = <0x11000 0x20>, <0x110a0 0x4>;
>  				#address-cells = <1>;
>  				#size-cells = <0>;
>  
> @@ -146,17 +146,14 @@ i2c0: i2c@...00{
>  				interrupts = <GIC_SPI 87 IRQ_TYPE_LEVEL_HIGH>;
>  				clock-frequency=<100000>;
>  
> -				pinctrl-names = "default", "gpio";
> +				pinctrl-names = "default";
>  				pinctrl-0 = <&i2c0_pins>;
> -				pinctrl-1 = <&i2c0_gpio>;
> -				scl-gpios = <&gpio0 26 (GPIO_ACTIVE_HIGH | GPIO_OPEN_DRAIN)>;
> -				sda-gpios = <&gpio0 27 (GPIO_ACTIVE_HIGH | GPIO_OPEN_DRAIN)>;

By doing this then older kernel won't be able to do recovery, while if
you keep it, the new kernels will still use new way to support recovery
thanks to the new reg filed added and old kernels will continue to work.

However, what we try to maintain is running new kernel on old dtb not
the opposite which is just a nice to have. At the end it is up to you,
if you really want to remove this chunk I will apply it once the driver
part of the series will be accepted.

Gregory


>  				status = "disabled";
>  			};
>  
>  			i2c1: i2c@...00{
>  				compatible = "marvell,mv78230-i2c";
> -				reg = <0x11100 0x20>;
> +				reg = <0x11100 0x20>, <0x110a4 0x4>;
>  				#address-cells = <1>;
>  				#size-cells = <0>;
>  
> @@ -165,11 +162,8 @@ i2c1: i2c@...00{
>  				interrupts = <GIC_SPI 88 IRQ_TYPE_LEVEL_HIGH>;
>  				clock-frequency=<100000>;
>  
> -				pinctrl-names = "default", "gpio";
> +				pinctrl-names = "default";
>  				pinctrl-0 = <&i2c1_pins>;
> -				pinctrl-1 = <&i2c1_gpio>;
> -				scl-gpios = <&gpio0 20 (GPIO_ACTIVE_HIGH | GPIO_OPEN_DRAIN)>;
> -				sda-gpios = <&gpio0 21 (GPIO_ACTIVE_HIGH | GPIO_OPEN_DRAIN)>;
>  				status = "disabled";
>  			};
>  
> -- 
> 2.42.0
>

-- 
Gregory Clement, Bootlin
Embedded Linux and Kernel engineering
http://bootlin.com