LCD Introduction ROC-3399-PC-PLUS development board supports two LCD screen interfaces by default, one is MIPI (compatible with 10.1 in. and 8 in. ), the other is EDP(10.1 in.). The positions of interfaces on the board are shown as follows: 10.1 in. MIPI 8 in. MIPI 10.1 in. EDP Config configuration Android7.1, for example, ROC-3399-PC-PLUS configuration file by default kernel/arch/arm64/configs/firefly_defconfig have LCD related configuration is set up, if you do the modification, please pay attention to add the following configuration: CONFIG_LCD_MIPI=y CONFIG_MIPI_DSI=y CONFIG_RK32_MIPI_DSI=y MIPI_DTS configuration Pin configuration The SDK of ROC-3399-PC-PLUS has two DTS files of MIPI DSI, which are used to adapt to the 10.1-inch screen and the 8-inch screen respectively. The corresponding path is: "kernel/arch/arm64/boot/dts/rockchip/rk3399-roc-pc-plus-mipi101.dts" and "kernel/arch/arm64/boot/dts/rockchip/rk3399-roc-pc-plus- mipi8.dts",Here in "kernel/arch/arm64/boot/dts/rockchip/rk3399-roc-pc- plus-mipi101.dts" as an example to tell the MIPI DTS file configuration screen. From the file "rk3399-roc-pc-plus-mipi101.dts" we can see the following statement: ... &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>; }; }; ... Power control pin of LCD is defined here: lcd_55power:(GPIO1_A3)GPIO_ACTIVE_HIGH lcd_rst:(GPIO4_D5)GPIO_ACTIVE_HIGH lcd_panel_enable：(GPIO1_D0)GPIO_ACTIVE_HIGH All are high level effective, please refer to the section of "GPIO" for specific pin configuration. MIPI Configure backlight A backlight interface is set outside the ROC-3399-PC-PLUS development board to control the backlight of the screen. In the DTS file : kernel/arch/arm64/boot/dts/rockchip/rk3399-roc-pc-plus-mipi101.dts configured in the backlight information, as follows: ... &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 >; enable-gpios = <&gpio1 24 GPIO_ACTIVE_HIGH>; pinctrl-names = "default"; pinctrl-0 = <&lcd_panel_enable>; }; ... }; Configure display timing Different from EDP screen, Timing of MIPI screen is written in DTS file. The following statement can be seen in kernel/arch/arm64/boot/dts/rockchip/rk3399-roc-pc-plus-mipi101.dts . display-timings { native-mode = <&timing0>; timing0: timing0 { clock-frequency = <70000000>;//<80000000>; hactive = <800>;//<768>; vactive = <1280>; hsync-len = <10>; //20, 50,10 hback-porch = <10>; //50, 56,10 hfront-porch = <180>;//50, 30,180 vsync-len = <4>;//4 vback-porch = <4>;//4 vfront-porch = <8>;//8 hsync-active = <0>; vsync-active = <0>; de-active = <0>; pixelclk-active = <0>; }; }; Kernel In kernel/drivers/gpu/drm/panel/panel-simple.c can be seen in panel_simple_probe initialization function to initialize the access sequence of functions. static int panel_simple_probe(struct device *dev, const struct panel_desc *desc){ ··· panel->base.funcs = &panel_simple_funcs; ··· } In kernel/drivers/gpu/drm/panel/panel-simple.c,you can see ： 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; } Initialization mipi screen after the electricity needs to send instruction to make it work, can be in kernel/arch/arm64/boot/dts/rockchip/rk3399-firefly-mipi101.dts can see mipi initialization in the command list: &dsi { status = "okay"; ... panel-init-sequence = [ 15 00 02 E0 00 15 00 02 E1 93 15 00 02 E2 65 15 00 02 E3 F8 15 00 02 E0 04 15 00 02 2D 03 15 00 02 E0 00 15 00 02 80 03 //15 00 02 4A 35 15 00 02 E0 01 15 00 02 00 00 15 00 02 E0 01 15 00 02 4B 04 //15 00 02 4A 35 15 00 02 00 00 15 00 02 01 66 //15 00 02 03 00 //15 00 02 04 6D 15 00 02 17 00 15 00 02 18 AF 15 00 02 19 01 15 00 02 1A 00 15 00 02 1B AF 15 00 02 1C 01 15 00 02 1F 3E 15 00 02 20 28 15 00 02 21 28 15 00 02 22 7E 15 00 02 35 05 15 00 02 37 09 15 00 02 38 04 15 00 02 39 00 15 00 02 3A 01 15 00 02 3C 76 15 00 02 3D FF 15 00 02 3E FF 15 00 02 3F 7F 15 00 02 40 06 15 00 02 41 A0 15 00 02 42 81 15 00 02 43 08 15 00 02 44 0B 15 00 02 45 28 //15 00 02 4B 04 15 00 02 55 0F 15 00 02 56 01 15 00 02 57 69 15 00 02 58 0A 15 00 02 59 0A 15 00 02 5A 29 15 00 02 5B 15 //GAMMA 15 00 02 5D 7C 15 00 02 5E 66 15 00 02 5F 57 15 00 02 60 4A 15 00 02 61 46 15 00 02 62 36 15 00 02 63 3A 15 00 02 64 23 15 00 02 65 3A 15 00 02 66 38 15 00 02 67 38 15 00 02 68 55 15 00 02 69 43 15 00 02 6A 4A 15 00 02 6B 3B 15 00 02 6C 36 15 00 02 6D 28 15 00 02 6E 15 15 00 02 6F 00 15 00 02 70 7C 15 00 02 71 66 15 00 02 72 57 15 00 02 73 4A 15 00 02 74 46 15 00 02 75 36 15 00 02 76 3A 15 00 02 77 23 15 00 02 78 3A 15 00 02 79 38 15 00 02 7A 38 15 00 02 7B 55 15 00 02 7C 43 15 00 02 7D 4A 15 00 02 7E 3B 15 00 02 7F 36 15 00 02 80 28 15 00 02 81 15 15 00 02 82 00 15 00 02 E0 02 15 00 02 00 1E 15 00 02 01 1E 15 00 02 02 41 15 00 02 03 41 15 00 02 04 43 15 00 02 05 43 15 00 02 06 1F 15 00 02 07 1F 15 00 02 08 35 15 00 02 09 1F 15 00 02 0A 15 15 00 02 0B 15 15 00 02 0C 1F 15 00 02 0D 47 15 00 02 0E 47 15 00 02 0F 45 15 00 02 10 45 15 00 02 11 4B 15 00 02 12 4B 15 00 02 13 49 15 00 02 14 49 15 00 02 15 1F 15 00 02 16 1E 15 00 02 17 1E 15 00 02 18 40 15 00 02 19 40 15 00 02 1A 42 15 00 02 1B 42 15 00 02 1C 1F 15 00 02 1D 1F 15 00 02 1E 35 15 00 02 1F 1F 15 00 02 20 15 15 00 02 21 15 15 00 02 22 1F 15 00 02 23 46 15 00 02 24 46 15 00 02 25 44 15 00 02 26 44 15 00 02 27 4A 15 00 02 28 4A 15 00 02 29 48 15 00 02 2A 48 15 00 02 2B 1F 15 00 02 2C 1F 15 00 02 2D 1F 15 00 02 2E 42 15 00 02 2F 42 15 00 02 30 40 15 00 02 31 40 15 00 02 32 1E 15 00 02 33 1E 15 00 02 34 1F 15 00 02 35 1F 15 00 02 36 1E 15 00 02 37 1E 15 00 02 38 1F 15 00 02 39 48 15 00 02 3A 48 15 00 02 3B 4A 15 00 02 3C 4A 15 00 02 3D 44 15 00 02 3E 44 15 00 02 3F 46 15 00 02 40 46 15 00 02 41 1F 15 00 02 42 1F 15 00 02 43 1F 15 00 02 44 43 15 00 02 45 43 15 00 02 46 41 15 00 02 47 41 15 00 02 48 1E 15 00 02 49 1E 15 00 02 4A 1E 15 00 02 4B 1F 15 00 02 4C 1E 15 00 02 4D 1E 15 00 02 4E 1F 15 00 02 4F 49 15 00 02 50 49 15 00 02 51 4B 15 00 02 52 4B 15 00 02 53 45 15 00 02 54 45 15 00 02 55 47 15 00 02 56 47 15 00 02 57 1F 15 00 02 58 40 15 00 02 59 00 15 00 02 5A 00 15 00 02 5B 30 15 00 02 5C 03 15 00 02 5D 30 15 00 02 5E 01 15 00 02 5F 02 15 00 02 60 30 15 00 02 61 01 15 00 02 62 02 15 00 02 63 14 15 00 02 64 6A 15 00 02 65 05 15 00 02 66 12 15 00 02 67 73 15 00 02 68 05 15 00 02 69 14 15 00 02 6A 6A 15 00 02 6B 08 15 00 02 6C 00 15 00 02 6D 00 15 00 02 6E 00 15 00 02 6F 88 15 00 02 70 00 15 00 02 71 00 15 00 02 72 06 15 00 02 73 7B 15 00 02 74 00 15 00 02 75 07 15 00 02 76 00 15 00 02 77 DD 15 00 02 78 17 15 00 02 79 0E 15 00 02 7A 03 15 00 02 7B 00 15 00 02 7C 00 15 00 02 7D 14 15 00 02 7E 6A 15 00 02 E0 04 //15 00 02 09 10 15 00 02 2B 2B 15 00 02 2E 44 15 00 02 09 11 15 00 02 2D 03 15 00 02 0E 48 // 15 00 02 E0 01 // 15 00 02 0E 01 15 00 02 E0 00 15 00 02 E6 02 15 00 02 E7 02 05 78 01 11 05 05 01 29 15 00 02 35 00 ]; panel-exit-sequence = [ 05 05 01 28 05 78 01 10 ]; ... }; Please refer to the following attachment for the command format and instructions: Rockchip DRM Panel Porting Guide.pdf Send instructions can be seen in the "kernel/drivers/gpu/drm/panel /panel-simple.c" : 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; } U-boot Send instructions can be seen in the u-boot/drivers/video /rockchip-dw-mipi-dsi.c : 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_DTS configuration Pin configuration RK3399-ROC-PC-PLUS's SDK with EDP DSI DTS file: kernel/arch/arm64/boot/dts/rockchip/rk3399-roc-pc-plus-edp.dts , we can see from the file the following statement: edp_panel: edp-panel { compatible = "simple-panel"; bus-format = ; 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>; }; */ }; }; ··· &pinctrl { lcd-panel { lcd_panel_reset: lcd-panel-reset { rockchip,pins = <4 29 RK_FUNC_GPIO &pcfg_pull_up>; }; lcd_panel_enable: lcd-panel-enable { rockchip,pins = <1 1 RK_FUNC_GPIO &pcfg_pull_up>; }; lcd_panel_pwr_en: lcd-panel-pwr-en { rockchip,pins = <2 5 RK_FUNC_GPIO &pcfg_pull_up>; }; }; }; Power control pin of LCD is defined here: lcd_en:(GPIO2_A4)GPIO_ACTIVE_HIGH lcd-edp-hpd:(GPIO1_D4)GPIO_ACTIVE_HIGH All are high level effective, please refer to the section of "GPIO" for specific pin configuration. EDP Configure backlight 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>; }; EDP configuration displays timing kernel writing Timing in the panel-simple.c , directly to the short string matching in drivers/gpu/drm/panel/panel-simple.c file has the following statement 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); The timing parameters are configured in the structure : lg_lp079qx1_sp0v_mode . U-boot The Timing is written in rockchip_panel.c, directly to the short string matching in drivers/video/rockchip_panel.c file has the following statement : 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_mode, }, }; The timing parameters are configured in the structure: lg_lp079qx1_sp0v_mode .