理解dtsi中的&

1 dtsi中的 & 怎么理解呢?

可以把它理解引用，因为dtsi中的每个模块（驱动程序）都是用｛｝包在内的，所以当你要修改某个模块A时，可以不直接在它定义的地方修改，可以别的地方（不在同一个文件，需要#include “被访问到的.dtsi”）采用如下方式：
&｛
modified: xxx
｝;

2 举例说明

2.1 两个模块的原始定义如下：

第一个 simple-panel-dsi 设备

dsi0_panel: panel@0 {
		status = "okay";
		compatible = "simple-panel-dsi";
		reg = <0>;
		num = <0>;
		id = [83 94];
		id-reg = <0x04>;
		backlight = <&backlight1>;
        pinctrl-names = "default";
        pinctrl-0 = <&lcd_rst>;
        reset-gpios = <&gpio3 RK_PC7 GPIO_ACTIVE_LOW>;
        init-delay-ms = <20>;
		reset-delay-ms = <60>;
		enable-delay-ms = <60>;
		prepare-delay-ms = <60>;
		unprepare-delay-ms = <60>;
		disable-delay-ms = <60>;
		dsi,flags = <(MIPI_DSI_MODE_VIDEO | MIPI_DSI_MODE_VIDEO_BURST |	MIPI_DSI_MODE_LPM)>;
		dsi,format = <MIPI_DSI_FMT_RGB888>;
		dsi,lanes  = <4>;

第二个 regulator-fixed 设备

vcc3v3_lcd0_n: vcc3v3-lcd0-n {
		compatible = "regulator-fixed";
		regulator-name = "vcc3v3_lcd0_n";
		regulator-boot-on;
		regulator-state-mem {
			regulator-off-in-suspend;
		};
	};

2.2 通过 & 引用并修改

&DSI0_PANEL {
	POWER-SUPPLY = <&VCC3V3_LCD0_N>; // POWER-SUPPLY 接收的是另一个设备VCC3V3_LCD0_N
};
VCC3V3_LCD0_N设备我要使用到它，但是也需要修改，继续用 &
&VCC3V3_LCD0_N {
	GPIO = <&GPIO3 RK_PC6 GPIO_ACTIVE_HIGH>;
	ENABLE-ACTIVE-HIGH;
};

3 一个补丁中用到的&

在rockchip某型开发板中，只支持显示3路输出（hdmi, mipi, lvds, edp四选三），以下补丁的内容是把关掉的hdmi重新打开，从中也可以体会到 ==&==的使用技法

diff --git a/kernel/arch/arm64/boot/dts/rockchip/rk3568-evb.dtsi b/kernel/arch/arm64/boot/dts/rockchip/rk3568-evb.dtsi
index f200c1cda..67a349d91 100755
--- a/kernel/arch/arm64/boot/dts/rockchip/rk3568-evb.dtsi
+++ b/kernel/arch/arm64/boot/dts/rockchip/rk3568-evb.dtsi
@@ -228,7 +228,7 @@
 	};
 	
 	edp-panel {
-		status = "okay";
+		status = "disabled";
 		compatible = "simple-panel";
 		backlight = <&backlight2>;
 		bus-format = <MEDIA_BUS_FMT_RGB888_1X24>;
@@ -1286,7 +1286,7 @@
 };
 
 &hdmi {
-	status = "disabled";
+	status = "okay";
 	rockchip,phy-table =
 		<92812500  0x8009 0x0000 0x0270>,
 		<165000000 0x800b 0x0000 0x026d>,
@@ -1297,7 +1297,7 @@
 };
 
 &hdmi_in_vp0 {
-	status = "disabled";
+	status = "okay";
 };
 
 &hdmi_in_vp1 {
@@ -1305,7 +1305,7 @@
 };
 
 &hdmi_sound {
-	status = "disabled";
+	status = "okay";
 };
 
 &i2c0 {
diff --git a/kernel/arch/arm64/boot/dts/rockchip/rk3568-evb1-ddr4-v10.dtsi b/kernel/arch/arm64/boot/dts/rockchip/rk3568-evb1-ddr4-v10.dtsi
index 37c013724..93206858b 100755
--- a/kernel/arch/arm64/boot/dts/rockchip/rk3568-evb1-ddr4-v10.dtsi
+++ b/kernel/arch/arm64/boot/dts/rockchip/rk3568-evb1-ddr4-v10.dtsi
@@ -370,7 +370,7 @@
 };
 
 &route_hdmi {
-	status = "disabled";
+	status = "okay";
 	connect = <&vp0_out_hdmi>;
 };
 
@@ -395,15 +395,15 @@
 &edp {
 	force-hpd;
 	//hpd-gpios = <&gpio0 RK_PC2 GPIO_ACTIVE_HIGH>;
-	status = "okay";
+	status = "disabled";
 };
 
 &edp_phy {
-	status = "okay";
+	status = "disabled";
 };
 
 &edp_in_vp0 {
-	status = "okay";
+	status = "disabled";
 };
 
 &edp_in_vp1 {

4 还可以用父与子的方式去理解

下图中提到的默认关闭是指 “status = “disabled”，在子dtsi中去打开它。

rk3568.dtsi理解为父dtsi, rk3568-evb.dtsi是子dtsi, rk3568-pinctrl.dtsi是专门用来书写pinctrl的dtsi