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
10.1寸 EDP
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
在
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。