MIPI-DSI液晶适配

原理

MIPI液晶屏首先需要对屏驱动IC进行初始化，写入相关指令数据，然后CPU的液晶控制器按照设定的图像时序参数向驱动IC输出图像数据。所以移植需要屏参（时序参数HBP、VBP一类的）和初始化代码两部分。

屏参修改

对于A33/A64/A40i需要找到FEX文件中找到lcd0参数块；对于A133需要在DTS里找到lcd0节点；以FEX文件为例：

[lcd0]

lcd_used = 1

lcd_driver_name = "AML080WQ05"

lcd_backlight = 100

lcd_if = 4

lcd_x = 800

lcd_y = 1280

lcd_width = 223

lcd_height = 125

lcd_dclk_freq = 70

lcd_pwm_used = 1

lcd_pwm_ch = 0

lcd_pwm_freq = 200

lcd_pwm_pol = 0

lcd_pwm_max_limit = 255

lcd_hbp = 40

lcd_ht = 888

lcd_hspw = 12

lcd_vbp = 20

lcd_vt = 1320

lcd_vspw = 4

lcd_lvds_if = 0

lcd_lvds_colordepth = 0

lcd_lvds_mode = 0

lcd_frm = 1

lcd_hv_clk_phase = 0

lcd_hv_sync_polarity = 0

lcd_dsi_if = 0

lcd_dsi_lane = 4

lcd_dsi_format = 0

lcd_dsi_te = 0

lcd_gamma_en = 0

lcd_bright_curve_en = 0

lcd_cmap_en = 0

lcd_driver_name为初始化代码的名字，后面会提到；lcd_if=4表示使用DSI显示接口；lcd_x/lcd_y/lcd_dclk_freq/lcd_hbp/lcd_ht/lcd_hspw/lcd_vbp/lcd_vt/lcd_vspw这9个参数需要对照液晶面板Datasheet上标注的参数对应填好；lcd_dsi_if/lcd_dsi_lane/lcd_dsi_format/lcd_dsi_te这4个参数对照上文填好即可，无需变动；

对于电源/引脚配置：

A33：确保有lcd_power = "axp22_dc1sw"这项即可；lcdd0~23/lcdclk/lcdde/lcdhsync/lcdvsync/[lcd0_suspend]块无用都可以删去；

A64/A40i：确保有lcd_power = "vcc-mipi"和lcd_fix_power = "vcc-dsi-33"，lcd_power为核心板VCC-MIPI输出（默认3V3），lcd_fix_power为CPU的DSI-Bank供电；lcdd0~23/lcdclk/lcdde/lcdhsync/lcdvsync/[lcd0_suspend]块无用都可以删去；

A133:确保有lcd_pin_power = "dcdc1"和lcd_power = "dc1sw"即可；确保引脚配置为pinctrl-0 = <&dsi4lane_pins_a>和pinctrl-1 = <&dsi4lane_pins_b>即可。

U-Boot部分修改

代码位置：

A33：lichee/brandy/u-boot-2011.09/drivers/video_sunxi/sunxi_v2/de_bsp/lcd/panels

A64/A40i：lichee/brandy/u-boot-2014.07/drivers/video/sunxi/disp2/disp/lcd

A133：longan/brandy/brandy-2.0/u-boot-2018/drivers/video/sunxi/disp2/disp/lcd

在这里添加panel初始化代码，可以先复制该目录下别的屏的.h和.c然后在此基础上修改，例如复制inet_dsi_panel.h和inet_dsi_panel.c，改名为AML080WQ05.h和AML080WQ05.c（文件名可以自己定义，尽量以屏型号命名）：

1) 将AML080WQ05.h中__INET_DIS_PANEL_H__替换为__AML080WQ05_H__；

2) AML080WQ05.c中#include "inet_dsi_panel.h"改为#include "AML080WQ05.h"；

3) AML080WQ05.c中__lcd_panel_t inet_dsi_panel = {改为__lcd_panel_t AML080WQ05_panel = {；

4) AML080WQ05.c中.name = "inet_dsi_panel"改为.name = "AML080WQ05"；

5) AML080WQ05.c中找到static struct LCM_setting_table LCM_LT080B21BA94_setting[] = {该行，在这里把屏厂提供的初始化代码贴过来，注意格式：{指令,参数长度,{参数1,参数2,...}}，提供的初始化代码若不是这种格式的需客户自己手工转换下！

6) 在panels.c中添加#include "AML080WQ05.h"；

7) 在panels.c中__lcd_panel_t* panel_array[] = {这个数组里添加&AML080WQ05_panel这项；

8) 在上层目录的Makefile里添加lcd/AML080WQ05.o以便将新增的.c编译进去；

9) 重新编译u-boot然后打包固件烧录验证；