u-boot和Linux内核的设备树文件在书写时是可以相互参考的

前言

这篇博文用以太网设备的设备树描述来得出一个重要结论：
u-boot和Linux内核的设备树文件在书写时是可以相互参考的。

这篇博文是博文 https://blog.youkuaiyun.com/wenhao_ir/article/details/145662136 附带产生的。

公板提供的u-boot和内核的对比

公板提供的u-boot的设备树文件对以太网设备的描述

文件位置：\uboot-imx\arch\arm\dts\imx6ul-14x14-evk.dtsi

&fec1 {
	pinctrl-names = "default";
	pinctrl-0 = <&pinctrl_enet1>;
	phy-mode = "rmii";
	phy-handle = <&ethphy0>;
	status = "okay";
};

&fec2 {
	pinctrl-names = "default";
	pinctrl-0 = <&pinctrl_enet2>;
	phy-mode = "rmii";
	phy-handle = <&ethphy1>;
	status = "okay";

	mdio {
		#address-cells = <1>;
		#size-cells = <0>;

		ethphy0: ethernet-phy@2 {
			reg = <2>;
			micrel,led-mode = <1>;
			clocks = <&clks IMX6UL_CLK_ENET_REF>;
			clock-names = "rmii-ref";
		};

		ethphy1: ethernet-phy@1 {
			reg = <1>;
			micrel,led-mode = <1>;
			clocks = <&clks IMX6UL_CLK_ENET2_REF>;
			clock-names = "rmii-ref";
		};
	};
};

公板提供的Linux内核的设备树文件对以太网设备的描述

在公板中，设备树文件imx6ull-14x14-evk.dts包含了设备树文件imx6ul-14x14-evk.dtsi，在设备树文件imx6ul-14x14-evk.dtsi有对以太网设备的描述，代码如下：

文件位置：/linux-imx/arch/arm/boot/dts/imx6ul-14x14-evk.dtsi

&fec1 {
	pinctrl-names = "default";
	pinctrl-0 = <&pinctrl_enet1>;
	phy-mode = "rmii";
	phy-handle = <&ethphy0>;
	status = "okay";
};

&fec2 {
	pinctrl-names = "default";
	pinctrl-0 = <&pinctrl_enet2>;
	phy-mode = "rmii";
	phy-handle = <&ethphy1>;
	status = "okay";

	mdio {
		#address-cells = <1>;
		#size-cells = <0>;

		ethphy0: ethernet-phy@2 {
			reg = <2>;
			micrel,led-mode = <1>;
			clocks = <&clks IMX6UL_CLK_ENET_REF>;
			clock-names = "rmii-ref";
		};

		ethphy1: ethernet-phy@1 {
			reg = <1>;
			micrel,led-mode = <1>;
			clocks = <&clks IMX6UL_CLK_ENET2_REF>;
			clock-names = "rmii-ref";
		};
	};
};

分析说明(完全一样)

我们对比二者，发现二者是完全一样的，所以可以说u-boot和Linux内核的设备树文件在书写时是可以相互参考的。

100ask提供的u-boot和内核的对比

100ask提供的u-boot的设备树文件对以太网设备的描述

文件位置：\uboot-imx\arch\arm\dts\imx6ul-14x14-evk.dtsi

&fec1 {
	pinctrl-names = "default";
	pinctrl-0 = <&pinctrl_enet1>;
	phy-mode = "rmii";
	phy-handle = <&ethphy0>;
	status = "disabled";
};

&fec2 {
	pinctrl-names = "default";
	pinctrl-0 = <&pinctrl_enet2>;
	phy-mode = "rmii";
	phy-handle = <&ethphy1>;
	phy-reset-gpios = <&gpio5 6 GPIO_ACTIVE_LOW>;
	phy-reset-duration = <26>;
	status = "okay";

	mdio {
		#address-cells = <1>;
		#size-cells = <0>;

		ethphy0: ethernet-phy@2 {
			reg = <0>;
			//micrel,led-mode = <1>;
			clocks = <&clks IMX6UL_CLK_ENET_REF>;
			clock-names = "rmii-ref";
		};

		ethphy1: ethernet-phy@1 {
			reg = <1>;
			//micrel,led-mode = <1>;
			clocks = <&clks IMX6UL_CLK_ENET2_REF>;
			clock-names = "rmii-ref";
		};
	};
};

100ask提供的Linux内核的设备树文件对以太网设备的描述

文件位置：/Linux-4.9.88/arch/arm/boot/dts/100ask_imx6ull-14x14.dts

&fec1 {
    pinctrl-names = "default";
    pinctrl-0 = <&pinctrl_enet1>;
    phy-mode = "rmii";
    phy-handle = <&ethphy0>;
    phy-reset-gpios = <&gpio5 9 GPIO_ACTIVE_LOW>;
    phy-reset-duration = <26>;
    status = "okay";
};

&fec2 {
    pinctrl-names = "default";
    pinctrl-0 = <&pinctrl_enet2>;
    phy-mode = "rmii";
    phy-handle = <&ethphy1>;
    phy-reset-gpios = <&gpio5 6 GPIO_ACTIVE_LOW>;
    phy-reset-duration = <26>;
    status = "okay";

    mdio {
        #address-cells = <1>;
        #size-cells = <0>;

        ethphy0: ethernet-phy@0 {
            compatible = "ethernet-phy-ieee802.3-c22";
            smsc,disable-energy-detect;
            reg = <0>;
        };
        ethphy1: ethernet-phy@1 {
            compatible = "ethernet-phy-ieee802.3-c22";
            smsc,disable-energy-detect;
            reg = <1>;
        };
    };
};

分析说明(大部分一样)

二者对比来看，u-boot是没有启用以太网1(fec1)的，只启用了以太网2(fec2)，原因在博文 https://blog.youkuaiyun.com/wenhao_ir/article/details/145662136 中有详细说明。

内核是以太网1(fec1)和以太网2(fec2)都启用了的。

既然二者都启用了以太网2(fec2)，我们就对比下二者对以太网2(fec2)的描述，结论是二者对以太网2(fec2)的描述虽然并不完全一样，但有很大部分是一样的，所以可以说u-boot和Linux内核的设备树文件在书写时是可以相互参考的。