LCD使用

简介

ROC-RK3399-PC Pro 开发板默认外置支持了两种 LCD 屏接口,一个是 MIPI(最大支持 2560x1600@60fps) 接口,另外一个是 EDP (最大支持 2K@60fps) 接口。硬件连接图参考如下:

  • 10.1 寸 MIPI _images/panel_mipi101.jpg

  • 10.1寸 EDP _images/panel_edp101.jpg

MIPI 驱动配置

引脚配置

关于引脚的配置,可以参考文件:kernel/arch/arm64/boot/dts/rockchip/rk3399-roc-pc-plus-mipi101-JDM101014_BC45_A1.dts

  • 芯片上电配置

    从文件 rk3399-roc-pc-plus-mipi101-JDM101014_BC45_A1.dts 我们可以看到以下内容:

    &dsi {
        ⋯
        power_ctr: power_ctr {
                rockchip,debug = <1>;
                power_enable = <1>;
                lcd_55power: lcd-55power {
                       gpios = <&gpio1 4 GPIO_ACTIVE_HIGH>;
                       pinctrl-names = "default";
                       pinctrl-0 = <&lcd_panel_55power>;
                       rockchip,delay = <6>;
                };         
                lcd_rst: lcd-rst {
                       gpios = <&gpio4 29 GPIO_ACTIVE_HIGH>;
                       pinctrl-names = "default";
                       pinctrl-0 = <&lcd_panel_reset>;
                       rockchip,delay = <6>;
                };
            };
        ⋯
    };
    
    ⋯
    
    &pinctrl {
    
        lcd-panel {
            lcd_panel_reset: lcd-panel-reset {
                rockchip,pins = <4 29 RK_FUNC_GPIO &pcfg_pull_down>;
        };
    
        lcd_panel_enable: lcd-panel-enable {
            rockchip,pins = <1 24 RK_FUNC_GPIO &pcfg_pull_down>;
        };
    
        lcd_panel_55power: lcd-panel-55power {
            rockchip,pins = <1 4 RK_FUNC_GPIO &pcfg_pull_down>;
        };
    };
    

    这里定义了LCD的电源控制引脚以及背光控制引脚:

    lcd_panel_reset:GPIO4_D5(GPIO_ACTIVE_HIGH)
    lcd_panel_enable:GPIO1_D0(GPIO_ACTIVE_HIGH)
    lcd_panel_55power:GPIO1_A4(GPIO_ACTIVE_HIGH)
    

    都是高电平有效,具体的引脚配置请参考《GPIO》一节。

  • 屏幕背光配置

    ROC-RK3399-PC Pro 开发板外置了一个背光接口用来控制屏幕背光。 从文件 rk3399-roc-pc-plus-mipi101-JDM101014_BC45_A1.dts 中配置了背光信息,如下:

    &backlight {
        status = "okay";
        pwms = <&pwm1 0 50000 1>;
        brightness-levels = <
                 /*0 23  23  24  24  25  25  26
                 87  87  87  87  87  87  87  87
                 87  87  87  87  87  87  87  87
                 87  87  87  87  87  87  87  87
                 87  87  87  87  87  87  87  87
                 87  87  87  87  87  87  87  87
                 87  87  87  87  87  87  87  87
                 87  87  87  87  87  87  87  87
                 87  87  87  87  87  87  87  87
                 87  87  87  87  87  87  87  87
                 88  89  90  91  92  93  94  95*/
                 96  97  98  99 100 101 102 103
                104 105 106 107 108 109 110 111
                112 113 114 115 116 117 118 119
                120 121 122 123 124 125 126 127
                128 129 130 131 132 133 134 135
                136 137 138 139 140 141 142 143
                144 145 146 147 148 149 150 151
                152 153 154 155 156 157 158 159
                160 161 162 163 164 165 166 167
                168 169 170 171 172 173 174 175
                176 177 178 179 180 181 182 183
                184 185 186 187 188 189 190 191
                192 193 194 195 196 197 198 198
                199 199 200 201 201 202 203 204
                205 206 207 208 209 210 211 212
                213 214 215 216 217 218 219 220
                221 222 223 224 225 226 227 228
                229 230 231 232 233 234 234 235
                236 237 238 239 240 241 242 243
                244 245 246 247 248 249 250 250
                250 250 250 250 250 250 250 250 >;
        default-brightness-level = <0>;
        enable-gpios = <&gpio1 24 GPIO_ACTIVE_HIGH>;
        //polarity = <1>;
        pinctrl-names = "default";
        pinctrl-0 = <&lcd_panel_enable>;
    };
    

显示时序配置

与EDP屏不同,MIPI 屏的 Timing 写在 DTS 文件中,从文件 rk3399-roc-pc-plus-mipi101-JDM101014_BC45_A1.dts 中可以看到以下内容:

&dsi{

⋯
    display-timings {
        native-mode = <&timing0>;
        timing0: timing0 {
                    clock-frequency = <72600000>;//<80000000>;
                    hactive = <800>;//<768>;
                    vactive = <1280>;
                    hsync-len = <14>;   //20, 50,10
                    hback-porch = <26>; //50, 56,10
                    hfront-porch = <32>;//50, 30,180
                    vsync-len = <8>;//4
                    vback-porch = <20>;//4
                    vfront-porch = <80>;//8
                    hsync-active = <0>;
                    vsync-active = <0>;
                    de-active = <0>;
                    pixelclk-active = <0>;
                };
    };
⋯
};

驱动上电时序简述

  • Kernel

    kernel/drivers/gpu/drm/panel/panel-simple.c 中可以看到在初始化函数 panel_simple_probe 中初始化了获取时序的函数。

    static int panel_simple_probe(struct device *dev, const struct panel_desc *desc){
    ⋯
     panel->base.funcs = &panel_simple_funcs;
    ⋯
    }
    

    该函数的在 kernel/drivers/gpu/drm/panel/panel-simple.c 中也有定义:

    static int panel_simple_get_timings(struct drm_panel *panel,unsigned int num_timings,struct display_timing *timings)
    {
        struct panel_simple *p = to_panel_simple(panel); 
        unsigned int i;
        if (!p->desc)  
            return 0;
    
        if (p->desc->num_timings < num_timings)  
            num_timings = p->desc->num_timings;
    
        if (timings)  
            for (i = 0; i < num_timings; i++)   
            timings[i] = p->desc->timings[i];
        return p->desc->num_timings;
    }
    

    MIPI 屏上电完成后需要发送初始化指令才能使之工作,可以在 rk3399-roc-pc-plus-mipi101-JDM101014_BC45_A1.dts 中可以看到 MIPI 的初始化指令列表:

    &dsi {      
        ⋯
          panel-init-sequence = [
            05 78 01 11
            05 32 01 29
        ];
    
        panel-exit-sequence = [
            05 00 01 28
            05 00 01 10
        ];
        ⋯
    };
    

    命令格式以及说明可参考以下附件: Rockchip DRM Panel Porting Guide.pdf 发送指令可以看到在 kernel/drivers/gpu/drm/panel/panel-simple.c 文件中的操作:

    static int panel_simple_enable(struct drm_panel *panel)
    {
        struct panel_simple *p = to_panel_simple(panel);
        int err;
        if (p->enabled)
            return 0;
        DBG("enter\n");
        if (p->on_cmds) {
            err = panel_simple_dsi_send_cmds(p, p->on_cmds);
            if (err)
                dev_err(p->dev, "failed to send on cmds\n");
        }
        if (p->desc && p->desc->delay.enable) {
            DBG("p->desc->delay.enable=%d\n", p->desc->delay.enable);
            msleep(p->desc->delay.enable);
        }
        if (p->backlight) {
            DBG("open backlight\n");
            p->backlight->props.power = FB_BLANK_UNBLANK;
            backlight_update_status(p->backlight);
        }
        p->enabled = true;
        return 0;
    }
    
  • Uboot

    发送指令可以看到在 u-boot/drivers/video/rockchip-dw-mipi-dsi.c文件中的操作:

    static int rockchip_dw_mipi_dsi_enable(struct display_state *state)
    {
        struct connector_state *conn_state = &state->conn_state;
        struct crtc_state *crtc_state = &state->crtc_state;
        const struct rockchip_connector *connector = conn_state->connector;
        const struct dw_mipi_dsi_plat_data *pdata = connector->data;
        struct dw_mipi_dsi *dsi = conn_state->private;
        u32 val;
        DBG("enter\n");
        dw_mipi_dsi_set_mode(dsi, DW_MIPI_DSI_VID_MODE);
        dsi_write(dsi, DSI_MODE_CFG, ENABLE_CMD_MODE);
        dw_mipi_dsi_set_mode(dsi, DW_MIPI_DSI_VID_MODE);
        if (!pdata->has_vop_sel)
            return 0;
        if (pdata->grf_switch_reg) {
            if (crtc_state->crtc_id)
                val = pdata->dsi0_en_bit | (pdata->dsi0_en_bit << 16);
            else
                val = pdata->dsi0_en_bit << 16;
            writel(val, RKIO_GRF_PHYS + pdata->grf_switch_reg);
        }
        debug("vop %s output to dsi0\n", (crtc_state->crtc_id) ? "LIT" : "BIG");
        //rockchip_dw_mipi_dsi_read_allregs(dsi);
        return 0;
    }
    

EDP 驱动配置

引脚配置

关于引脚的配置,可以参考文件:kernel/arch/arm64/boot/dts/rockchip/rk3399-roc-pc-plus-edp.dts

  • 芯片上电配置

    从文件:kernel/arch/arm64/boot/dts/rockchip/rk3399-roc-pc-plus-edp.dts 文件中我们可以看到以下内容:

    edp_panel: edp-panel {
    		compatible = "simple-panel";
    		bus-format = <MEDIA_BUS_FMT_RGB666_1X18>;
    
    		backlight = <&backlight>;
    
    		display-timings {
    			native-mode = <&timing0>;
    
    			timing0: timing0 {
    				clock-frequency = <200000000>;
    				hactive = <2560>;
    				vactive = <1600>;
    				hfront-porch = <48>;
    				hsync-len = <80>;
    				hback-porch = <32>;
    				vfront-porch = <2>;
    				vsync-len = <39>;
    				vback-porch = <5>;
    				hsync-active = <0>;
    				vsync-active = <0>;
    				de-active = <0>;
    				pixelclk-active = <0>;
    			};
    		};
    
    		ports {
    			panel_in_edp: endpoint {
    				remote-endpoint = <&edp_out_panel>;
    			};
    		};
    
    		power_ctr: power_ctr {
                   rockchip,debug = <1>;
                   lcd_en: lcd-en {
                           gpios = <&gpio2 5 GPIO_ACTIVE_HIGH>;
    					   pinctrl-names = "default";
    					   pinctrl-0 = <&lcd_panel_enable>;
                           rockchip,delay = <1000>;
                   };
    			   /*
                   lcd_edp_hpd: lcd-edp-hpd {
                           gpios = <&gpio1 20 GPIO_ACTIVE_HIGH>;
    					   pinctrl-names = "default";
    					   pinctrl-0 = <&lcd_edp_hpd_enable>;
                           rockchip,delay = <10>;
                   };
    			   */
           };
    	};
    

    这里定义了LCD的电源控制引脚:

    lcd_en:GPIO2_A4(GPIO_ACTIVE_HIGH)
    lcd-edp-hpd:GPIO1_D4(GPIO_ACTIVE_HIGH)
    

    都是高电平有效,具体的引脚配置请参考《GPIO》一节。

  • 屏幕背光配置

    backlight: backlight {
    		status = "okay";
    		compatible = "pwm-backlight";
    		pwms = <&pwm0 0 25000 0>;
    		enable-gpios = <&gpio1 24 GPIO_ACTIVE_HIGH>;
    		pinctrl-names = "default";
    		pinctrl-0 = <&lcd_backlight_enable>;
    		brightness-levels = <
    		  0   1   2   3   4   5   6   7
    		  8   9  10  11  12  13  14  15
    		 16  17  18  19  20  21  22  23
    		 24  25  26  27  28  29  30  31
    		 32  33  34  35  36  37  38  39
    		 40  41  42  43  44  45  46  47
    		 48  49  50  51  52  53  54  55
    		 56  57  58  59  60  61  62  63
    		 64  65  66  67  68  69  70  71
    		 72  73  74  75  76  77  78  79
    		 80  81  82  83  84  85  86  87
    		 88  89  90  91  92  93  94  95
    		 96  97  98  99 100 101 102 103
    		104 105 106 107 108 109 110 111
    		112 113 114 115 116 117 118 119
    		120 121 122 123 124 125 126 127
    		128 129 130 131 132 133 134 135
    		136 137 138 139 140 141 142 143
    		144 145 146 147 148 149 150 151
    		152 153 154 155 156 157 158 159
    		160 161 162 163 164 165 166 167
    		168 169 170 171 172 173 174 175
    		176 177 178 179 180 181 182 183
    		184 185 186 187 188 189 190 191
    		192 193 194 195 196 197 198 199
    		200 201 202 203 204 205 206 207
    		208 209 210 211 212 213 214 215
    		216 217 218 219 220 221 222 223
    		224 225 226 227 228 229 230 231
    		232 233 234 235 236 237 238 239
    		240 241 242 243 244 245 246 247
    		248 249 250 251 252 253 254 255>;
    	default-brightness-level = <200>;
    };
    

驱动上电时序简述

  • Kernel

    内核把 Timing 写在 panel-simple.c 中, 直接以短字符串匹配在 drivers/gpu/drm/panel/panel-simple.c 文件中有以下语句

    static const struct drm_display_mode lg_lp079qx1_sp0v_mode = {
      .clock = 200000,
      .hdisplay = 1536,
      .hsync_start = 1536 + 12,
      .hsync_end = 1536 + 12 + 16,
      .htotal = 1536 + 12 + 16 + 48,
      .vdisplay = 2048,
      .vsync_start = 2048 + 8,
      .vsync_end = 2048 + 8 + 4,
      .vtotal = 2048 + 8 + 4 + 8,
      .vrefresh = 60,
      .flags = DRM_MODE_FLAG_NVSYNC | DRM_MODE_FLAG_NHSYNC,
    };
    
    static const struct panel_desc lg_lp097qx1_spa1 = {
      .modes = &lg_lp097qx1_spa1_mode,
      .num_modes = 1,
      .size = {
        .width = 320,
        .height = 187,
      },
    };
    
    ⋯
    
    static const struct of_device_id platform_of_match[] = {
      {
        .compatible = "simple-panel",
        .data = NULL,
      },{
    
      }, {
        .compatible = "lg,lp079qx1-sp0v",
        .data = &lg_lp079qx1_sp0v,
      }, {
    
      }, {
        /* sentinel */
      }
    };
    
    ⋯
    
    MODULE_DEVICE_TABLE(of, platform_of_match); 
    

    时序参数在结构体 lg_lp079qx1_sp0v_mode 中配置。

  • Uboot

    uboot 把 Timing 写在 rockchip_panel.c 中, 直接以短字符串匹配在 drivers/video/rockchip_panel.c 文件中有以下语句:

    static const struct drm_display_mode lg_lp079qx1_sp0v_mode = {
      .clock = 200000,
      .hdisplay = 1536,
      .hsync_start = 1536 + 12,
      .hsync_end = 1536 + 12 + 16,
      .htotal = 1536 + 12 + 16 + 48,
      .vdisplay = 2048,
      .vsync_start = 2048 + 8,
      .vsync_end = 2048 + 8 + 4,
      .vtotal = 2048 + 8 + 4 + 8,
      .vrefresh = 60,
      .flags = DRM_MODE_FLAG_NVSYNC | DRM_MODE_FLAG_NHSYNC,
    };
    static const struct rockchip_panel g_panel[] = {
      {
        .compatible = "lg,lp079qx1-sp0v",
        .mode = &lg_lp079qx1_sp0v_mode,
      }, {
        .compatible = "auo,b125han03",
        .mode = &auo_b125han03_mod e,
      },
    };
    

    时序的参数在结构体 lg_lp079qx1_sp0v_mode 中配置。