4. HDMI 接口设备树配置：RK3399 HDMI 控制器节点、PHY 配置、DDC 通道、音频与视频参数

RK3399 的 HDMI 接口基于 Synopsys DesignWare HDMI 2.0 TX 控制器，集成在 SoC 内部。设备树配置需要正确描述控制器基地址、中断、时钟、PHY 初始化参数、DDC 通道映射以及音视频时序参数。本章将逐一拆解这些节点，并给出经过验证的参考配置。

4.1 HDMI 控制器节点结构

RK3399 的 HDMI 控制器在设备树中通常位于 i2c 或 display-subsystem 下，主节点定义如下：

hdmi: hdmi@ff940000 {
    compatible = "rockchip,rk3399-hdmi";
    reg = <0x0 0xff940000 0x0 0x20000>;
    interrupts = <GIC_SPI 23 IRQ_TYPE_LEVEL_HIGH 0>;
    clocks = <&cru PCLK_HDMI_CTRL>,
             <&cru SCLK_HDMI_CEC>,
             <&cru SCLK_HDMI_PHY>;
    clock-names = "pclk", "cec", "phy";
    pinctrl-names = "default";
    pinctrl-0 = <&hdmi_i2c_xfer>,
                <&hdmi_cec>;
    power-domains = <&power RK3399_PD_HDCP>;
    status = "disabled";
};

4.2 PHY 配置节点

RK3399 HDMI PHY 是独立的 IP 模块，基地址为 0xff968000。PHY 节点负责配置 TMDS 时钟、预加重、摆幅等模拟参数。

hdmi_phy: hdmi-phy@ff968000 {
    compatible = "rockchip,rk3399-hdmi-phy";
    reg = <0x0 0xff968000 0x0 0x4000>;
    clocks = <&cru SCLK_HDMI_PHY>,
             <&cru PCLK_HDMI_PHY>;
    clock-names = "ref", "pclk";
    #phy-cells = <0>;
    status = "disabled";
};

PHY 与控制器通过 phys 和 phy-names 属性连接：

&hdmi {
    phys = <&hdmi_phy>;
    phy-names = "hdmi_phy";
};

4.3 DDC 通道配置

DDC（Display Data Channel）用于读取显示器的 EDID 信息。RK3399 的 HDMI 控制器内部集成 DDC 控制器，通过 I2C 总线与显示器通信。设备树中通过 ddc-i2c-bus 属性指定 I2C 总线：

&hdmi {
    ddc-i2c-bus = <&i2c5>;
};

I2C 节点本身需要配置正确的引脚复用：

&i2c5 {
    status = "okay";
    pinctrl-names = "default";
    pinctrl-0 = <&i2c5_xfer>;
};

4.4 音频与视频参数配置

HDMI 支持音频和视频同步传输。设备树中通过 audio-ports 和 port 子节点配置音视频通道。

4.4.1 视频端口绑定

&hdmi {
    ports {
        #address-cells = <1>;
        #size-cells = <0>;

        port@0 {
            reg = <0>;
            hdmi_in_vopb: endpoint {
                remote-endpoint = <&vopb_out_hdmi>;
            };
        };

        port@1 {
            reg = <1>;
            hdmi_out: endpoint {
                remote-endpoint = <&hdmi_con>;
            };
        };
    };
};

port@0 连接 VOP（Video Output Processor）的 vopb 或 vopl，port@1 连接外部 HDMI 连接器。

4.4.2 音频参数

RK3399 HDMI 音频通过 I2S 接口传输。设备树中需使能 I2S 节点并关联 HDMI：

&i2s2 {
    status = "okay";
    rockchip,i2s-broken-bclk = <1>;
};

&hdmi {
    #sound-dai-cells = <0>;
    hdmi_audio: hdmi-audio {
        compatible = "rockchip,hdmi-audio";
        status = "okay";
    };
};

4.5 HDMI 设备树完整配置流程

下图展示了 RK3399 HDMI 设备树各节点之间的依赖关系：

4.6 视频时序参数配置

HDMI 输出分辨率通过 VOP 的 display-timings 子节点配置。以下为 1080p@60Hz 的典型时序：

display-timings {
    native-mode = <&timing0>;
    timing0: timing0 {
        clock-frequency = <148500000>;
        hactive = <1920>;
        vactive = <1080>;
        hfront-porch = <88>;
        hsync-len = <44>;
        hback-porch = <148>;
        vfront-porch = <4>;
        vsync-len = <5>;
        vback-porch = <36>;
        hsync-active = <0>;
        vsync-active = <0>;
        de-active = <0>;
        pixelclk-active = <0>;
    };
};

4.7 完整 HDMI 设备树示例

以下为 RK3399 EVB 开发板的 HDMI 完整配置片段：

&hdmi {
    status = "okay";
    ddc-i2c-bus = <&i2c5>;
    phys = <&hdmi_phy>;
    phy-names = "hdmi_phy";
    #sound-dai-cells = <0>;
    pinctrl-names = "default";
    pinctrl-0 = <&hdmi_i2c_xfer>,
                <&hdmi_cec>;
};

&hdmi_phy {
    status = "okay";
};

&i2c5 {
    status = "okay";
    pinctrl-names = "default";
    pinctrl-0 = <&i2c5_xfer>;
};

&i2s2 {
    status = "okay";
    rockchip,i2s-broken-bclk = <1>;
};

&vopb {
    status = "okay";
};

&vopb_mmu {
    status = "okay";
};