LCD使用 简介 AIO-3399J开发板外置了两个LCD屏接口,一个是EDP,一个是LVDS,接口对应板 子上的位置如下图: LVDS屏 DTS配置 引脚配置 AIO-3399J的SDK有LVDS DSI的DTS文件: kernel/arch/arm64/boot/dts/rockchip/rk3399-firefly-aio-lvds.dts,从该 文件中我们可以看到以下语句: / { model = "AIO Board lvds (Android)"; compatible = "rockchip,android", "rockchip,rk3399-firefly-lvds", "rockchip,rk3399"; test-power { status = "okay"; }; ... &dsi { status = "okay"; dsi_panel: panel { compatible ="simple-panel-dsi"; reg = <0>; //ddc-i2c-bu //power-supply = <&vcc_lcd>; //pinctrl-0 = <&lcd_panel_reset &lcd_panel_enable>; backlight = <&backlight>; /* enable-gpios = <&gpio1 1 GPIO_ACTIVE_LOW>; reset-gpios = <&gpio4 29 GPIO_ACTIVE_LOW>; */ dsi,flags = <(MIPI_DSI_MODE_VIDEO | MIPI_DSI_MODE_VIDEO_BURST | MIPI_DSI_MODE_LPM | MIPI_DSI_MODE_EOT_PACKET)>; dsi,format = ; //bus-format = ; dsi,lanes = <4>; dsi,channel = <0>; enable-delay-ms = <35>; prepare-delay-ms = <6>; unprepare-delay-ms = <0>; disable-delay-ms = <20>; size,width = <120>; size,height = <170>; status = "okay"; ... power_ctr: power_ctr { rockchip,debug = <0>; lcd_pwr_en: lcd-pwr-en { gpios = <&gpio3 16 GPIO_ACTIVE_HIGH>; pinctrl-names = "default"; pinctrl-0 = <&lcd_panel_pwr_en>; rockchip,delay = <10>; }; lcd_rst: lcd-rst { gpios = <&gpio2 27 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 = <2 27 RK_FUNC_GPIO &pcfg_pull_down>; }; lcd_panel_pwr_en: lcd-panel-pwr-en { rockchip,pins = <3 16 RK_FUNC_GPIO &pcfg_pull_down>; }; }; }; 这里定义了LCD的电源控制引脚: lcd_pwr_en:(GPIO3_C0)GPIO_ACTIVE_HIGH lcd_rst:(GPIO2_D3)GPIO_ACTIVE_HIGH 都是高电平有效,具体的引脚配置请参考《GPIO》一节。 配置背光 AIO-3399J开发板外置了一个背光接口用来控制屏幕背光,如下图所示: 在DTS文件:kernel/arch/arm64/boot/dts/rockchip/rk3399-firefly- core.dtsi中配置了背光信息,如下: / { compatible = "rockchip,rk3399-firefly-core", "rockchip,rk3399"; backlight: backlight { status = "disabled"; compatible = "pwm-backlight"; pwms = <&pwm0 0 25000 0>; 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>; }; pwms属性:配置PWM,范例里面默认使用pwm0,25000ns是周期(40 KHz)。LVDS需 要加背光电源控制脚,在kernel/arch/arm64/boot/dts/rockchip/rk3399 -firefly-aio-lvds.dts中可以看到以下语句: &backlight { status = "okay"; enable-gpios = <&gpio1 1 GPIO_ACTIVE_HIGH>; brightness-levels = < 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>; }; 因此使用时需修改DTS文件。 brightness-levels属性:配置背光亮度数组,最大值为255,配置暗区和亮区, 并把亮区数组做255的比例调节。比如范例中暗区是255-221,亮区是220-0。 default-brightness-level属性:开机时默认背光亮度,范围为0-255。 具体请 参考kernel中的说明文档: kernel/Documentation/devicetree/bindings/leds/backlight/pwm- backlight.txt 配置显示时序 与EDP屏不同,LVDS屏的 Timing 写在DTS文件中,在 kernel/arch/arm64/boot/dts/rockchip/rk3399-firefly-aio-lvds.dts中可以 看到以下语句: disp_timings: display-timings { native-mode = <&timing0>; timing0: timing0 { clock-frequency = <80000000>; hactive = <768>; vactive = <1024>; hsync-len = <20>; //20, 50 hback-porch = <130>; //50, 56 hfront-porch = <150>;//50, 30 vsync-len = <40>; vback-porch = <130>; vfront-porch = <136>; hsync-active = <0>; vsync-active = <0>; de-active = <0>; pixelclk-active = <0>; }; } } 时序属性参考下图: Init Code lvds屏上完电后需要发送初始化指令才能使之工作。初始化指令需要以下工具文 档生成,下载 TC358764_5_774_5XBG_DSI-LVDS_Tv11p_nm_1280x800.xls 如何配置LVDS panel-init-sequence 以1280x800单lvds为例: 首先打开TC358764_5_774_5XBG_DSI- LVDS_Tv11p_nm_1280x800.xls 选择页面"Timing Parameters_SYNC_EVENT", 按照LVDS屏的时序填入LVDS timing黄色单元,一般只需填入以下单元即可。 HPW / HBPR / HDISPR / HFPR 分别对应 hsync-len / hback-porch / hactive / hfront-porch VPW / VBPR / VDISPR / VFPR 分别对应 vhsync-len / vback-porch / vactive / vfront-porch LVDS timing填入完成后还需配置常规参数 1.根据LVDS屏规格书确认LVDS Link和LVDS output format并选择屏的参数。 2.计算LVDS clock(蓝色单元无法写入,需要黄色单元自动计算得出),需要填入 DSI Clock(HOST), Pixel Clock Source, Pixel Clock Divider。计算公式如下 :DSI Clock/Pixel Clock Source/Pixel Clock Divider=LVDS Clock 填入上述黄色单元基本上完成配置,接下来选择页面"Source"即可看到转换后的 Comment 以上面为例"013C 00030005",mipi command就应该是"29 02 06 3C 01 05 00 03 00" 29 : packet ID 02 : 2ms delay 06 : 6 bytes 3C 01 : address = 0x013C 00 03 00 05 : data=0x05000300 将页面source所有地址写入数据,即可完成初始化指令panel-init-sequence。 dts在kernel/arch/arm64/boot/dts/rockchip/rk3399-firefly-aio-lvds.dts中 可以看到lvds的初始化指令列表: &dsi { status = "okay"; ... panel-init-sequence = [ 29 00 06 3C 01 09 00 07 00 29 00 06 14 01 06 00 00 00 29 00 06 64 01 0B 00 00 00 29 00 06 68 01 0B 00 00 00 29 00 06 6C 01 0B 00 00 00 29 00 06 70 01 0B 00 00 00 29 00 06 34 01 1F 00 00 00 29 00 06 10 02 1F 00 00 00 29 00 06 04 01 01 00 00 00 29 00 06 04 02 01 00 00 00 29 00 06 50 04 20 01 F0 03 29 00 06 54 04 32 00 B4 00 29 00 06 58 04 80 07 48 00 29 00 06 5C 04 0A 00 19 00 29 00 06 60 04 38 04 0A 00 29 00 06 64 04 01 00 00 00 29 01 06 A0 04 06 80 44 00 29 00 06 A0 04 06 80 04 00 29 00 06 04 05 04 00 00 00 29 00 06 80 04 00 01 02 03 29 00 06 84 04 04 07 05 08 29 00 06 88 04 09 0A 0E 0F 29 00 06 8C 04 0B 0C 0D 10 29 00 06 90 04 16 17 11 12 29 00 06 94 04 13 14 15 1B 29 00 06 98 04 18 19 1A 06 29 02 06 9C 04 33 04 00 00 ]; panel-exit-sequence = [ 05 05 01 28 05 78 01 10 ]; ... }; 命令格式以及说明可参考以下附件: Rockchip DRM Panel Porting Guide.pdf kernel 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; } u-boot 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; } 常见问题 1. 画面抖动闪屏 排查屏参数是否超出屏规格书限定周期,排查屏时钟大小。"Timing Parameters_SYNC_EVENT"所有参数变动必须和comment同步调整。 2. 颜色显示异常 尝试同步调整color mapping或者lvds timing。 NOTE : 页面"How to use"有详细步骤,其他参数说明可以参考文档"页面"菜单。