[ROC-RK3568-PC] [Firefly-Android] 10min带你了解LCD的使用

Posted 2023-03-12 Neutionwei

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文章目录

一、内核Config配置

ROC-RK3568-PC的SDK下kernel/arch/arm64/configs/firefly_defconfig已经把LCD相关的配置好：

CONFIG_DRM_ROCKCHIP=y
CONFIG_ROCKCHIP_DW_MIPI_DSI=y
CONFIG_DRM_PANEL_SIMPLE=y

二、MIPI配置

ROC-RK3568-PC的SDK有MIPI DSI的DTS文件： kernel/arch/arm64/boot/dts/rockchip/rk3568-firefly-roc-pc-mipi101_M101014_BE45_A1.dts，此DTS文件为MIPI_DSI0+HDMI屏配置，MIPI_DSI1 默认关闭。

2.1 引脚配置

从DTS文件中可以看到以下语句：

#include "rk3568-firefly-roc-pc.dtsi"

/ 
    model = "ROC-RK3568-PC MIPI M101014_BE45_A1 + HDMI(android)";
    compatible = "rockchip,rk3568-firefly-roc-pc-mipi", "rockchip,rk3568";
    ...


&route_dsi0 
    status = "okay";
    logo,rotation = "logo_rotation_270"; //support rotation 90,180,270
    connect = <&vp1_out_dsi0>;
;

&video_phy0 
    status = "okay";
;

&dsi0_in_vp0 
    status = "disabled";
;

&dsi0_in_vp1 
    status = "okay";
;

/*
 * mipi_dphy0 needs to be enabled
 * when dsi0 is enabled
 */
&dsi0 
    status = "okay";
    //rockchip,lane-rate = <1000>;
    dsi0_panel: panel@0 
        status = "okay";
        compatible = "simple-panel-dsi";
        reg = <0>;
        backlight = <&backlight>;

        enable-gpios = <&gpio0 RK_PC7 GPIO_ACTIVE_HIGH>;
        reset-gpios = <&gpio3 RK_PB5 GPIO_ACTIVE_LOW>;

        enable-delay-ms = <35>;
        prepare-delay-ms = <6>;
        reset-delay-ms = <25>;
        init-delay-ms = <55>;
        unprepare-delay-ms = <0>;
        disable-delay-ms = <20>;
        mipi-data-delay-ms = <200>;
        ...
        panel-init-sequence = [
            //39 00 04 B9 83 10 2E
            // 15 00 02 CF FF
            05 78 01 11
            05 32 01 29
            //15 00 02 35 00
        ];

        panel-exit-sequence = [
            05 00 01 28
            05 00 01 10
        ];
        ...
    ;
;
...
&route_hdmi 
    status = "okay";
    connect = <&vp0_out_hdmi>;
;

&hdmi 
    status = "okay";
;

&hdmi_in_vp0 
    status = "okay";
;

&hdmi_in_vp1 
    status = "disabled";
;
...

这里定义了LCD的控制引脚：

NAME	GPIO	GPIO ACTIVE
LCD_EN	GPIO0_C7	GPIO_ACTIVE_HIGH
LCD_RST	GPIO3_B5	GPIO_ACTIVE_LOW

在硬件信号上 LCD_EN 引脚高电平有效，而 LCD_RST 引脚是低电平有效。

2.2 背光配置

在DTS文件中配置了背光信息，如下：

    backlight: backlight 
        status = "okay";
        compatible = "pwm-backlight";
        enable-gpios = <&gpio3 RK_PB0 GPIO_ACTIVE_HIGH>;
        pwms = <&pwm4 0 50000 1>;
        brightness-levels = <
             60  60  60  61  61  61  62  62
             62  63  63  63  64  64  64  65
             65  65  66  66  66  67  67  67
             68  68  68  69  69  69  70  70
             70  71  71  71  72  72  72  73
             73  73  74  74  74  75  75  75
             76  76  76  77  77  77  78  78
             78  79  79  79  80  80  80  81
             81  81  82  82  82  83  83  83
             84  84  84  85  85  85  86  86
             86  87  87  87  88  88  88  89
             89  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>;
    ;

enable-gpios：背光使能脚，高电平有效。
pwms属性：配置PWM，范例里面默认使用pwm4，50000ns是周期(20 KHz)，pwm为负极性。
brightness-levels属性：配置背光亮度数组，一般以值 255 为一个 scale，当 PWM 设置为正极性时，从 0~255 表示背光为正极，占空比从 0%~100% 变化，255~0 为负极性，占空比从 100%~0% 变化；当 PWM 设置为负极性时，反之。
default-brightness-level属性：开机时默认背光亮度，范围为0-255。

具体可参考kernel中的说明文档：kernel/Documentation/devicetree/bindings/leds/backlight/pwm-backlight.txt

2.3 显示时序配置

2.3.1 Power on/off sequence

MIPI屏的上下电时序通常都在规格书的Power on/off sequence章节中，可根据规格书的上下电时序修改dts，panel节点中有如下属性:

&dsi0 
    status = "okay";
    //rockchip,lane-rate = <1000>;
    dsi0_panel: panel@0 
        status = "okay";
        compatible = "simple-panel-dsi";
        ...
        enable-delay-ms = <35>;
        prepare-delay-ms = <6>;
        reset-delay-ms = <25>;
        init-delay-ms = <55>;
        unprepare-delay-ms = <0>;
        disable-delay-ms = <20>;
        mipi-data-delay-ms = <200>;
        ...
    ;
;

mipi-data-delay-ms为Firefly 10.1寸 M101014-BE45-A1 MIPI屏所需时序，调试屏幕时可根据本身上下电时序是否需要再配置此属性。MIPI上下电后需要发送初始化或退出指令才能使之正常工作，初始化和退出指令列表可以参考kernel/arch/arm64/boot/dts/rockchip/rk3568-firefly-roc-pc-mipi101_CZNB101862T.dts，列表如下：

&dsi0 
	status = "okay";
	//rockchip,lane-rate = <1000>;
	dsi0_panel: panel@0 
        ...
        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
            ...
        ];

        panel-exit-sequence = [
            05 05 01 28
            05 78 01 10
        ];
    ;
;

dts中的init-sequence和panel-exit-sequence，只是配置了上电和下电指令, 其他的初始化指令已经烧录在M101014-BE45-A1这款MIPI屏的IC里，dts无需配置。接下来来看看上下电时序在驱动中的实现，具体实现在kernel/drivers/gpu/drm/panel/panel-simple.c中：

static int panel_simple_disable(struct drm_panel *panel)

    ...
	if (p->backlight) 
		p->backlight->props.power = FB_BLANK_POWERDOWN;
		p->backlight->props.state |= BL_CORE_FBBLANK;
		backlight_update_status(p->backlight);
	

	if (p->desc->delay.disable)
		panel_simple_sleep(p->desc->delay.disable);

	if (p->cmd_type == CMD_TYPE_MCU) 
		err = panel_simple_xfer_mcu_cmd_seq(p, p->desc->exit_seq);
		if (err)
			dev_err(panel->dev, "failed to send exit cmds seq\\n");
	
    ...


static int panel_simple_unprepare(struct drm_panel *panel)

    ...
	if (p->desc->exit_seq) 
		if (p->dsi)
			panel_simple_xfer_dsi_cmd_seq(p, p->desc->exit_seq);
		else if (p->cmd_type == CMD_TYPE_SPI)
			err = panel_simple_xfer_spi_cmd_seq(p, p->desc->exit_seq);
		if (err)
			dev_err(panel->dev, "failed to send exit cmds seq\\n");
	

	gpiod_direction_output(p->reset_gpio, 1);
	if(!p->enable_on_always)
		gpiod_direction_output(p->enable_gpio, 0);
	
    ...


static int panel_simple_prepare(struct drm_panel *panel)

    ...
	gpiod_direction_output(p->enable_gpio, 1);

	if (p->desc->delay.prepare)
		panel_simple_sleep(p->desc->delay.prepare);

    ...
	gpiod_direction_output(p->reset_gpio, 1);

	if (p->desc->delay.reset)
		panel_simple_sleep(p->desc->delay.reset);

	gpiod_direction_output(p->reset_gpio, 0);  //由于驱动在控制reset脚时序的时候使用了`gpiod`这类的API
                                                   //如果在DTS配置了低电平有效，那么这里就会将reset引脚拉高，即取反。
	if (p->desc->delay.init)
		panel_simple_sleep(p->desc->delay.init);

	if (p->desc->init_seq) 
		if (p->dsi)
			panel_simple_xfer_dsi_cmd_seq(p, p->desc->init_seq);
		else if (p->cmd_type == CMD_TYPE_SPI)
			err = panel_simple_xfer_spi_cmd_seq(p, p->desc->init_seq);
		if (err)
			dev_err(panel->dev, "failed to send init cmds seq\\n");
	

    if(p->desc->delay.mipi_data)
        panel_simple_sleep(p->desc->delay.mipi_data);
    
    ...


static int panel_simple_enable(struct drm_panel *panel)

    ...
	if (p->cmd_type == CMD_TYPE_MCU) 
		err = panel_simple_xfer_mcu_cmd_seq(p, p->desc->init_seq);
		if (err)
			dev_err(panel->dev, "failed to send init cmds seq\\n");
	
	if (p->desc->delay.enable)
		panel_simple_sleep(p->desc->delay.enable);

	if (p->backlight) 
		p->backlight->props.state &= ~BL_CORE_FBBLANK;
		p->backlight->props.power = FB_BLANK_UNBLANK;
		backlight_update_status(p->backlight);
	
    ...

2.3.2 Display-Timings

display_timings在dts中定义：

    disp_timings0: display-timings 
        native-mode = <&dsi0_timing0>;
        dsi0_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>;
        ;
    ;

相关的参数一般可以在屏的规格书中找到，然后在kernel/drivers/gpu/drm/panel/panel-simple.c的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;
	...

...
static const struct drm_panel_funcs panel_simple_funcs = 
	.loader_protect = panel_simple_loader_protect,
	.disable = panel_simple_disable,
	.unprepare = panel_simple_unprepare,
	.prepare = panel_simple_prepare,
	.enable = panel_simple_enable,
	.get_modes = panel_simple_get_modes,
	.get_timings = panel_simple_get_timings,
;
...

该函数在kernel/drivers/gpu/drm/panel/panel-simple.c中定义：

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->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;

三、EDP配置

3.1 引脚配置

ROC-RK3568-PC的SDK有EDP的DTS文件：kernel/arch/arm64/boot/dts/rockchip/rk3568-firefly-roc-pc-edp_M156X40.dts，从该文件中我们可以看到以下语句：

    edp_panel: edp-panel 
        compatible = "simple-panel";
        status = "okay";
        power-supply = <&vcc3v3_lcd_edp>;
        enable-gpios = <&gpio3 RK_PC3 GPIO_ACTIVE_HIGH>;
        //bus-format = <MEDIA_BUS_FMT_RBG888_1X24>;		
        backlight = <&backlight>;
        ...
        ports 
            panel_in_edp: endpoint 
                remote-endpoint = <&edp_out_panel>;
            ;
        ;
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