Use a 7 inch TFT display with RoadRunner SOM

This article explain how to manage a 7 inch TFT display using the DPI port of RoarRunner SOM

Wirings

Data lines:

Example of wiring in 666 mode with a TFT display:

LCD 7 inch
1 VLED-
2 VLED+
3 GND	GND
4 3V3	3V3
5 R0	GND
6 R1	GND
7 R2	PC22
8 R3	PC23
9 R4	PC24
10 R5	PC25
11 R6	PC26
12 R7	PC27
13 G0	GND
14 G1	GND
15 G2	PC16
16 G3	PC17
17 G4	PC18
18 G5	PC19
19 G6	PC20
20 G7	PC21
21 B0	GND
22 B1	GND
23 B2	PC10
24 B3	PC11
25 B4	PC12
26 B5	PC13
27 B6	PC14
28 B7	PC15
29 GND
30 PCLK	PD0
31 DISP	3V3
32 HSYNC	PC31
33 VSYNC	PC30
34 DE	PD1
35 NC
36 GND	GND
37 NC
38 NC
39 NC
40 NC

Device tree apb section

hlcdc: hlcdc@f0000000 {
    status = "okay";

    hlcdc-display-controller {

        pinctrl-names = "default";
        pinctrl-0 = <&pinctrl_lcd_base &pinctrl_lcd_rgb666>;

        port@0 {
            #address-cells = <1>;
            #size-cells = <0>;
            hlcdc_panel_output: endpoint@0 {
                reg = <0>;
                remote-endpoint = <&panel_input>;
            };
        };
    };

    hlcdc_pwm: hlcdc-pwm {
        pinctrl-names = "default";
        pinctrl-0 = <&pinctrl_lcd_pwm>;
    };

};  

backlight: backlight {
    compatible = "pwm-backlight";
    pwms = <&hlcdc_pwm 0 50000 0>;
    brightness-levels = <0 4 8 16 32 64 128 255>;
    default-brightness-level = <7>;
    power-supply = <&bl_reg>;
    status = "okay";
};

bl_reg: backlight_regulator {
    compatible = "regulator-fixed";
    regulator-name = "backlight-power-supply";
    regulator-min-microvolt = <5000000>;
    regulator-max-microvolt = <5000000>;
    status = "okay";
};

panel: panel {
    /* compatible = "pda,91-00156-a0", "simple-panel"; */
    compatible = "innolux,g070y2-l01", "simple-panel";
    backlight = <&backlight>;
    power-supply = <&panel_reg>;
    #address-cells = <1>;
    #size-cells = <0>;
    status = "okay";

    port@0 {
        reg = <0>;
        #address-cells = <1>;
        #size-cells = <0>;

        panel_input: endpoint@0 {
            reg = <0>;
            remote-endpoint = <&hlcdc_panel_output>;
        };
    };
};

panel_reg: panel_regulator {
    compatible = "regulator-fixed";
    regulator-name = "panel-power-supply";
    regulator-min-microvolt = <3300000>;
    regulator-max-microvolt = <3300000>;
    status = "okay";
};

i2c0: i2c@f8028000 {
    dmas = <0>, <0>;
    pinctrl-names = "default","gpio";
    pinctrl-0 = <&pinctrl_i2c0_default>;
    pinctrl-1 = <&pinctrl_i2c0_gpio>;
    i2c-analog-filter;
    i2c-digital-filter;
    i2c-digital-filter-width-ns = <35>;
    sda-gpios = <&pioA PIN_PD21 GPIO_ACTIVE_HIGH>;
    scl-gpios = <&pioA PIN_PD22 (GPIO_ACTIVE_HIGH | GPIO_OPEN_DRAIN)>;
    status = "disabled";

    gt9271: gt9271@5d {
            compatible = "goodix,gt9271";
            reg = <0x5D>;
            interrupt-parent = <&pioA>;
            interrupts = <PIN_PC7 IRQ_TYPE_LEVEL_LOW>;
    };

};

Device tree - pinctrl@fc038000 section

pinctrl_lcd_base: pinctrl_lcd_base {
    pinmux = <PIN_PC30__LCDVSYNC>,
         <PIN_PC31__LCDHSYNC>,
         <PIN_PD1__LCDDEN>,
         <PIN_PD0__LCDPCK>;
    bias-disable;
    /* atmel,drive-strength = <ATMEL_PIO_DRVSTR_ME>; */
};


pinctrl_lcd_rgb666: pinctrl_lcd_rgb666 {
    pinmux = <PIN_PC10__LCDDAT2>,
         <PIN_PC11__LCDDAT3>,
         <PIN_PC12__LCDDAT4>,
         <PIN_PC13__LCDDAT5>,
         <PIN_PC14__LCDDAT6>,
         <PIN_PC15__LCDDAT7>,
         <PIN_PC16__LCDDAT10>,
         <PIN_PC17__LCDDAT11>,
         <PIN_PC18__LCDDAT12>,
         <PIN_PC19__LCDDAT13>,
         <PIN_PC20__LCDDAT14>,
         <PIN_PC21__LCDDAT15>,
         <PIN_PC22__LCDDAT18>,
         <PIN_PC23__LCDDAT19>,
         <PIN_PC24__LCDDAT20>,
         <PIN_PC25__LCDDAT21>,
         <PIN_PC26__LCDDAT22>,
         <PIN_PC27__LCDDAT23>;
    bias-disable;
};

pinctrl_lcd_pwm: pinctrl_lcd_pwm {
    pinmux = <PIN_PC28__LCDPWM>;
    bias-disable;
};