[RK3566] 通过GM8775 点LVDS屏调试记录

平台：RK3566 Android11

         GM8775 MIPI转LVDS

屏：LVDS 1920x1200 分辨率

1.先看屏规格书，计算后将屏分辨率及前后肩填入PC端工具进行转换

根据屏规格书把屏参写入工具生成一段初始化参数

 注意检查：1.硬件使用的外部晶振还是MIPI时钟

                   2.硬件使用的是用的IIC还是command

 2.将工具生成的屏参写入平台所使用的dts文件

        IC是通过mipi转LVDS，在dts中配置成mipi通道

2.1 dts配置如下：

&dsi0 {
	status = "okay";
	panel@0 {
		status = "okay";
		compatible ="simple-panel-dsi";
		reg = <0>;
		backlight = <&backlight>;
		//power-supply=<&vcc_3v3>;
		enable-gpios = <&gpio3 RK_PD6 GPIO_ACTIVE_HIGH>;
		prepare-delay-ms = <100>;
		reset-gpios = <&gpio4 RK_PA0 GPIO_ACTIVE_HIGH>;
		reset-delay-ms = <100>;
		init-delay-ms  = <100>;
		enable-delay-ms = <100>;
		pinctrl-names = "default";
		pinctrl-0 = <&lcd_enable_gpio>, <&lcd_rst_gpio>;
		dsi,flags = <(MIPI_DSI_MODE_VIDEO | MIPI_DSI_MODE_VIDEO_BURST |
			      MIPI_DSI_MODE_LPM | MIPI_DSI_MODE_EOT_PACKET)>;
		dsi,format = <MIPI_DSI_FMT_RGB888>;
		dsi,lanes = <4>;
    	panel-init-sequence = [
			23 00 02 27 AA
			23 00 02 48 02
			23 00 02 B6 20
			23 00 02 01 80
			23 00 02 02 B0
			23 00 02 03 47
			23 00 02 04 46
			23 00 02 05 14
			23 00 02 06 46
			23 00 02 07 00
			23 00 02 08 0A
			23 00 02 09 0F
			23 00 02 0A 0A
			23 00 02 0B 82
			23 00 02 0C 13
			23 00 02 0D 01
			23 00 02 0E 80
			23 00 02 0F 20
			23 00 02 10 20
			23 00 02 11 03
			23 00 02 12 1B
			23 00 02 13 63
			23 00 02 14 01
			23 00 02 15 23
			23 00 02 16 40
			23 00 02 17 00
			23 00 02 18 01
			23 00 02 19 23
			23 00 02 1A 40
			23 00 02 1B 00
			23 00 02 1E 46
			23 00 02 51 30
			23 00 02 1F 10
			23 00 02 2A 01     //如上为工具生成的初始化代码
            //如下为SSR展频，不加可能点不亮
			23 00 02 6A	08 
			23 00 02 6C	9E
			23 00 02 6D 07
			23 00 02 6E	00
			23 00 02 6F	8A
			23 00 02 70 19
			23 64 02 71 00
    	];
      	disp_timings1: display-timings {
			native-mode = <&timing2>;
			timing2: timing2 {
			clock-frequency = <144250000>;
				hactive = <1920>;
				vactive = <1200>;
				hback-porch = <70>;
				hsync-len = <20>;
				hfront-porch = <70>;
				vback-porch = <10>;
				vfront-porch = <10>;
				vsync-len = <15>;
				hsync-active = <0>;
				vsync-active = <0>;
				de-active = <0>;
				pixelclk-active = <0>;
			};
		};

修改后编译烧录看看效果

FAQ：

1.GM8775C拥有自测模式，不需要MIPI数据就能显示，初步调试可优先进入彩条模式，排除后端问题  将 23 00 02 2A 01 修改为 23 00 02 2A 4D

2.GM8775C的data di必须是0x23 ，发送完后示波器测量：CLK/DATA 是否有输出

3.颜色显示异常，可在屏规格书上查找屏支持的LVDS数据格式是JEIDA或是VESA

4.双路LVDS出现显示重影，请排除LVDS奇偶是不是反了，可对调下ODD/EVEN试下