MIPI

4 Dec 2024

Read time: 4 minute(s)

每一款 MIPI 屏都需要一个独立的驱动程序，因此调试 MIPI 屏时，不仅需要在 DTS 中设置参数，还需要在 kernel 和 uboot 中添加屏幕所对应的驱动：

uboot 配置

在 Luban 根目录下执行 make um，进入 uboot 的功能配置界面，使能显示模块驱动：

Device Drivers
    Graphics support
        ArtInChip Graphics  --->
            [*]   Enable ArtInChip Video Support
            [ ]   ArtInChip display rgb support
            [ ]   ArtInChip display lvds support
            [ ]   ArtInChip display mipi-dsi support
            <*>   ArtInChip Panel Drivers (ArtInChip panel driver for B080XAN)  --->

kernel 配置

在 Luban 根目录下执行 make km，进入 kernel 的功能配置界面，使能显示模块驱动：

Device Drivers
    Graphics support
        ArtInChip Graphics  --->
            <*> ArtInChip Framebuffer support
            [ ]   ArtInChip display rgb support
            [ ]   ArtInChip display lvds support
            [*]   ArtInChip display mipi-dsi support
            <*>   ArtInChip Panel Drivers (ArtInChip panel driver for B080XAN)  --->

uboot dts

uboot 如果要进行显示，则声明相应的配置为预加载，以 demo88_nand 工程为例，文件为 target/d211/demo88_nand/board-u-boot.dtsi

声明通路

&disp {
    u-boot,dm-pre-reloc;
    fb0: fb@0 {
        u-boot,dm-pre-reloc;
        port {
            fb0_out: endpoint {
                u-boot,dm-pre-reloc;
            };
        };
    };
};
&de0 {
    u-boot,dm-pre-reloc;
    port@0 {
        de0_in: endpoint {
            u-boot,dm-pre-reloc;
        };
    };

    port@1 {
        de0_out: endpoint {
            u-boot,dm-pre-reloc;
        };
    };
};
&dsi0 {                     //mipi dsi
    u-boot,dm-pre-reloc;
    port@0 {
        dsi0_in: endpoint {
            u-boot,dm-pre-reloc;
        };
    };

    port@1 {
        dsi0_out: endpoint {
            u-boot,dm-pre-reloc;
        };
    };
};

声明屏幕参数

panel_dsi {
    u-boot,dm-pre-reloc;
    port {
        panel_dsi_in: endpoint {
            u-boot,dm-pre-reloc;
        };
    };
};

声明屏幕引脚

dsi_pins: dsi-0 {
        u-boot,dm-pre-reloc;
    pins {
        u-boot,dm-pre-reloc;
    };
};

系统 dts

系统的 dts 将进行完整的功能配置，以 demo128_nand 工程为例，文件为 target/d211/demo128_nand/board.dts 中

配置通路

通过 port 和 status 结点，定义了一条数据通道

fb       |      de    |     |     mipi    |     panel
port  --> port0   port1 -->  port0   port1 -->  port

&fb0 {
    port {
        fb0_out: endpoint {
            remote-endpoint = <&de0_in>;
        };
    };
};

&de0 {
    status = "okay";
    port@0 {
        reg = <0>;
        de0_in: endpoint {
            remote-endpoint = <&fb0_out>;
        };
    };

    port@1 {
        reg = <1>;
        de0_out: endpoint {
            remote-endpoint = <&dsi0_in>;   //mipi dsi
        };
    };
};

&dsi0 {
    pinctrl-names = "default";
    pinctrl-0 = <&dsi_pins>;
    status = "okay";

    data-clk-inverse;

    port@0 {
        reg = <0>;
        dsi0_in: endpoint {
            remote-endpoint = <&de0_out>;
        };
    };

    port@1 {
        reg = <1>;
        dsi0_out: endpoint {
            remote-endpoint = <&panel_dsi_in>;
        };
    };
};

配置屏幕参数

    panel_dsi {
    compatible = "artinchip,aic-dsi-panel-simple";
    status = "okay";

    enable-gpios = <&gpio_c 6 GPIO_ACTIVE_HIGH>;

    port {
        panel_dsi_in: endpoint {
            remote-endpoint = <&dsi0_out>;
        };
    };
};

配置引脚
引脚的配置统一在 d211-pinctrl.dtsi 中完成，在 rgb0 节点中直接进行了引用
```
&dsi0 {
    pinctrl-names = "default";
    pinctrl-0 = <&dsi_pins>;
    status = "okay";
    ......
}
```