RK3568系列16——eDP屏幕配置

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　　eDP屏幕由于具有和屏幕的双向通信能力，其目标就是取代已落后LVDS屏幕，且由于eDP屏幕不需要传输时钟信号，其配置方式较为简单。

预备知识

  • eDP屏幕只需要传输数据信号，不需要时钟信号
  • eDP屏幕硬件上总共有三路链接信号：
  • Main Link：主数据线，可以是1/2/4 Line模式
  • AUX Channel：辅助通道，用于传输控制指令
  • HPD：热插拔信号，用于检测屏幕是否连接

原理图分析

  • 硬件接口只接了2条Main Link
  • 没有接HPD信号
  • 一个用于控制屏幕供电开关的GPIO
  • 一个用于控制背光供电开关的GPIO
  • 一个用于控制屏幕背光升压电路的GPIO

配置要点

  • 要为panel配置一个regulator，且在其中配置相关GPIO
  • 也要为backlight配置一个regulator，且在其中配置相关GPIO

DTS配置

　　关于屏幕参数配置请参考前文《RK3568系列14——屏幕参数公共配置》。

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#include <dt-bindings/display/media-bus-format.h>

/ {
    edp-panel {
        compatible = "simple-panel";
        power-supply = <&vcc3v3_edp_panel>;
        backlight = <&backlight>;
        prepare-delay-ms = <20>;
        enable-delay-ms = <20>;
        disable-delay-ms = <20>;
        unprepare-delay-ms = <20>;
        bpc = <8>; // color bits 6|8
        bus-format = <MEDIA_BUS_FMT_RGB888_1X24>;

        // eDP屏幕可以通过AUX通道交换屏幕参数信息，但是RK还是建议代码中写死
        display-timings {
            native-mode = <&lcd_auo_b133han05e>;
            lcd_auo_b133han05e: lcd-auo-b133han05e {
                clock-frequency = <142600000>;
                hactive = <1920>;
                hfront-porch = <80>;
                hback-porch = <70>;
                hsync-len = <10>;
                vactive = <1080>;
                vfront-porch = <32>;
                vback-porch = <20>;
                vsync-len = <10>;
                hsync-active = <0>;
                vsync-active = <0>;
                de-active = <0>;
                pixelclk-active = <0>;
            };
        };

        port {
            panel_in_edp: endpoint {
                remote-endpoint = <&edp_out_panel>;
            };
        };
    };

    vcc3v3_edp_panel: vcc3v3-edp-panel {
        compatible = "regulator-fixed";
        regulator-name = "vcc3v3_edp";
        regulator-min-microvolt = <3300000>;
        regulator-max-microvolt = <3300000>;
        gpio = <&gpio1 RK_PD1 GPIO_ACTIVE_HIGH>; // eDP屏幕供电使能
        enable-active-high;
        pinctrl-names = "default";
        pinctrl-0 = <&edp_panel_enable>;
        vin-supply = <&vcc3v3_sys>;
        regulator-boot-on;
        regulator-state-mem {
            regulator-off-in-suspend;
        };
    };

    vcc12v0_edp_backlight: vcc12v0-edp-backlight {
        compatible = "regulator-fixed";
        regulator-name = "vcc12v0_edp_backlight";
        regulator-min-microvolt = <12000000>;
        regulator-max-microvolt = <12000000>;
        gpio = <&gpio0 RK_PC3 GPIO_ACTIVE_HIGH>; // eDP背光升压电路使能
        enable-active-high;
        pinctrl-names = "default";
        pinctrl-0 = <&edp_backlight_power>;
        vin-supply = <&vcc5v0_sys>;
        regulator-boot-on;
        regulator-state-mem {
            regulator-off-in-suspend;
        };
    };
};

&pinctrl {
    edp {
        edp_panel_enable: edp-panel-enable {
            rockchip,pins = <1 RK_PD1 RK_FUNC_GPIO &pcfg_pull_down>;
        };
        edp_backlight_power: edp-backlight-power {
            rockchip,pins = <0 RK_PC3 RK_FUNC_GPIO &pcfg_pull_down>;
        };
        edp_backlight_enable: edp-backlight-enable {
            rockchip,pins = <0 RK_PB7 RK_FUNC_GPIO &pcfg_pull_down>;
        };
    };
};

&edp {
    status = "okay";
    // hpd-gpios = <&gpio4 RK_PC7 GPIO_ACTIVE_HIGH> // 有HPD信号则配置此项
    force-hpd; // 无HPD信号则配置此项

    ports {
        port@1 {
            reg = <1>;

            edp_out_panel: endpoint@0 {
                remote-endpoint = <&panel_in_edp>;
            };
        };
    };
};

&edp_phy {
    status = "okay";
};

&edp_in_vp0 {
    status = "disabled";
};

&edp_in_vp1 {
    status = "okay";
};

&route_edp {
    status = "okay";
    connect = <&vp1_out_edp>;
};

&backlight {
    status = "okay";
    pwms = <&pwm5 0 1000000 0>;
    power-supply = <&vcc12v0_edp_backlight>;
    enable-gpios = <&gpio0 RK_PB7 GPIO_ACTIVE_HIGH>; // eDP背光供电使能
    pinctrl-names = "default";
    pinctrl-0 = <&edp_backlight_enable>;
};

遇到的问题

  • 若控制屏幕供电开关的GPIO配置在panel里时，drm框架启动会报错，猜测原因是eDP辅助通道没有上拉供电，无法交换信息，因此要配在panel的regulator中
  • 屏幕没有接HPD信号，无法点亮，因此要配置force-hpd，让CPU忽略热插拔检测

参考文档

  • RKDocs/common/display/Rockchip_Developer_Guide_DRM_Panel_Porting_CN.pdf