STM32MP157A驱动开发 | 05 - 基于LTDC接口驱动RGB LCD

Step1. 添加LCD设备树描述，包括背光节点和ltdc节点
Step2. 驱动文件里添加一组设备ID

一、添加设备树描述

1. 修改ltdc节点描述

比较重要的属性是remote-endpoint，描述ltdc输出到哪里。

2. 添加ltdc输出接口描述

: rgblcd {
    compatible = "bearpi,rgblcd";
    backlight = &rgblcd_backlight;
    status = "okay";

    port {
      rgblcd_in: endpoint {
        remote-endpoint = <<dc_ep0_out>;
      };
    };
  };

其中remote-endpoint用于告诉屏幕驱动数据从哪里获得。

3. 添加backlight节点

: rgblcd-backlight {
    compatible = "gpio-backlight";
        gpios = <&gpioe 9 GPIO_ACTIVE_HIGH>;
    default-on;
    status = "okay";
  };

二、在驱动中添加屏幕参数

1. 添加屏幕参数描述

static const struct drm_display_mode bearpi_rgblcd_mode = {
    .clock = 51200,
    .hdisplay = 800,
    .hsync_start = 800 + 46,
    .hsync_end = 800 + 46 + 1,
    .htotal = 800 + 46 + 1 + 210,
    .vdisplay = 480,
    .vsync_start = 480 + 23,
    .vsync_end = 480 + 23 + 1,
    .vtotal = 480 + 23 + 1 + 22,
    .flags = DRM_MODE_FLAG_NVSYNC | DRM_MODE_FLAG_NHSYNC,
};

static const struct panel_desc bearpi_rgblcd_desc = {
    .modes = &bearpi_rgblcd_mode,
    .num_modes = 1,
    .bpc = 6,
    .size = {
        .width = 152,
        .height = 91,
    },
    .bus_format = MEDIA_BUS_FMT_RGB888_1X24,
    .bus_flags = DRM_BUS_FLAG_DE_HIGH | DRM_BUS_FLAG_PIXDATA_DRIVE_POSEDGE,
};

2. 添加设备兼容性

三、测试