高通移植mipi LCD的过程LK代码

lk部分：（实现LCD兼容）

1. 函数定位

aboot_init()来到target_display_init()；
这就是高通原生lk LCD 兼容的关键所在。至于你需要兼容多少LCD 就在while（）设置了，具体代码就不跟下去了。

然后根据target中的不同文件来判断是否进入哪一个函数来处理：
target_display_init() 函数里有很重要函数就是gcdb_display_init();

如果平台支持屏幕最大个数自动检测，msm8953支持兼容两个屏。(GCDB：Global Component Database全局组件数据库)；

gcdb_display_init初始化pll_clk_func、power_func、bl_func等功能（指明相应的函数指针），初始化好之后就调用msm_display_init()函数。

在msm_display_init()里先Turn on panel，再Turn on backlight；

panel.power_func = mdss_dsi_panel_power;		//turn on panel
panel.bl_func = mdss_dsi_bl_enable;				//turn on backlight

函数指向相应的函数中去；

2. 打开lcd

/* Turn on panel */

1. 调用mdss_dsi_panel_power()中的regulator_enable()给L2、L6、L17供电

if (pdata->power_func)
	ret = pdata->power_func(1, &(panel->panel_info));

2. 调用mdss_dsi_mipi_dfps_config函数：

if (pdata->dfps_func)
		ret = pdata->dfps_func(&(panel->panel_info));

3. 调用mdss_dsi_panel_clock()

调用calculate_clock_config(pinfo)计算时钟配置和调用target_panel_clock(enable, pinfo)配置目标panel的时钟。

4. 分配并设置帧缓存：

msm_fb_alloc(&(panel->fb))和fbcon_setup(&(panel->fb))为帧缓冲器(frame buffer)分配内存。

5. 获取logo图片：

调用fetch_image_from_partition()从splash分区获取lk logo图片，如果splash分区没有满足要求的数据，就显示默认的logo。

6. DSI转HDMI：

if ((panel->dsi2HDMI_config) && (panel->panel_info.has_bridge_chip))
		ret = panel->dsi2HDMI_config(&(panel->panel_info));

7. msm_display_config()函数：

7.1 mdss_dsi_phy_init()

mdss_dsi_phy_init(&mipi_pinfo,MIPI_DSI0_BASE, DSI0_PHY_BASE);
       if(pinfo->mipi.dual_dsi)

如果有两个MIPI DSI接口MIPI_DSI0和MIPI_DSI1就调用两次mdss_dsi_phy_init()，msm8909只有MIPI_DSI0，MSM8994等有两个DSI接口。

mdss_dsi_phy_init(&mipi_pinfo,MIPI_DSI1_BASE, DSI1_PHY_BASE);

7.2 ret = mdss_dsi_host_init(mipi, mipi->dual_dsi, mipi->broadcast);
初始化DSI接口的host控制器。

7.3 调用if (panel->pre_init_func) {}函数：
static int mdss_dsi_panel_pre_init(void)
{
intret = NO_ERROR;

   if(panelstruct.paneldata->panel_lp11_init) {
          ret= mdss_dsi_panel_reset(1);
          if(ret) {
                 dprintf(CRITICAL,"panel reset failed
");
                 returnret;
          }
   }

   if(panelstruct.paneldata->panel_init_delay)
          udelay(panelstruct.paneldata->panel_init_delay);

   dprintf(SPEW,"Panel pre init done
");
   returnret;

}
因为panelstruct.paneldata->panel_lp11_init在init_panel_data()函数赋值为1，所以调用mdss_dsi_panel_reset()根据reset时序来复位panel。

8. ret = msm_display_on();

主要部分：

case MIPI_VIDEO_PANEL:
		dprintf(INFO, "Turn on MIPI_VIDEO_PANEL.
");
		ret = mdp_dsi_video_on(pinfo);
		if (ret)
			goto msm_display_on_out;

		ret = mdss_dsi_post_on(panel);
		if (ret)
			goto msm_display_on_out;

		ret = mipi_dsi_on(pinfo);
		if (ret)
			goto msm_display_on_out;
		break;

8.1 调用mdp_dsi_video_on()使能DSI VIDEO
8.2 mdss_dsi_post_on()使用初始化命令来初始化panel
8.3 mipi_dsi_on()

9. 打开背光：

/* Turn on backlight */
if (pdata->bl_func)
	ret = pdata->bl_func(1);

3. 增加一个panel需要做的事：

1、在gcdb_display_init()函数中有一个函数oem_panel_select()函数：

（这个函数需要做的工作是：主要是识别不同IC，赋值给参数panel_id，panel_id的使用在同一文件中的 init_panel_data()函数中。）

pan_type = oem_panel_select(panel_name, &panelstruct, &(panel.panel_info),
				 &dsi_video_mode_phy_db);

2、uint32_t hw_id = board_hardware_id();

//判断是高通哪一款平台，这里不需要看，hw_id是不需要管的，因为在下面语句中会直接跳到init_panel_data函数中来

3、在oem_panel_select()函数中需要根据你的hw_id来确定使用哪一款的LCD；

panel_override_id = panel_name_to_id(supp_panels,
				ARRAY_SIZE(supp_panels), panel_name);
supp_panels是struct panel_list，如果要增加一个panel就需要在这里增加一个supp_panels，例如：
static struct panel_list supp_panels[] = {
	{"truly_1080p_video", TRULY_1080P_VIDEO_PANEL},
	{"truly_1080p_cmd", TRULY_1080P_CMD_PANEL},
	{"r69006_1080p_video", R69006_1080P_VIDEO_PANEL},
	{"r69006_1080p_cmd", R69006_1080P_CMD_PANEL},
	{"truly_wuxga_video", TRULY_WUXGA_VIDEO_PANEL},
	{"nt35523_720p_video", NT35523_720P_VIDEO_PANEL},
	{"a914_nhd_video", A914_NHD_VIDEO_PANEL},
};

4、在这个枚举中也需要增加相应的panel：

/*---------------------------------------------------------------------------*/
enum {
	TRULY_1080P_VIDEO_PANEL,
	TRULY_1080P_CMD_PANEL,
	R69006_1080P_VIDEO_PANEL,
	R69006_1080P_CMD_PANEL,
	TRULY_WUXGA_VIDEO_PANEL,
	NT35523_720P_VIDEO_PANEL,
	A914_NHD_VIDEO_PANEL,
	UNKNOWN_PANEL
};

if (panel_name) {
		panel_override_id = panel_name_to_id(supp_panels,
				ARRAY_SIZE(supp_panels), panel_name);

		if (panel_override_id < 0) {
			dprintf(CRITICAL, "Not able to search the panel:%s
",
					 panel_name + strspn(panel_name, " "));
		} else if (panel_override_id < UNKNOWN_PANEL) {
			/* panel override using fastboot oem command */
			panel_id = panel_override_id;

			dprintf(INFO, "OEM panel override:%s
",
					panel_name + strspn(panel_name, " "));
			goto panel_init;
		}
	}
	……
panel_init:
	/*
	 * Update all data structures after 'panel_init' label. Only panel
	 * selection is supposed to happen before that.
	 */
	pinfo->pipe_type = MDSS_MDP_PIPE_TYPE_RGB;
	return init_panel_data(panelstruct, pinfo, phy_db);

确保能直接跳到panel_init函数中来；

5、同样来到init_panel_data()函数中来：

在这里也需要增加一个panel：（当然了，要增加相应的头文件#include "include/panel_a914_nhd_video.h"这个头文件是LCM供应商给的文件，一般来说都要自己根据时序图来参照）

case TRULY_WUXGA_VIDEO_PANEL:
		panelstruct->paneldata    = &truly_wuxga_video_panel_data;
		panelstruct->paneldata->panel_with_enable_gpio = 1;
		panelstruct->panelres     = &truly_wuxga_video_panel_res;
		panelstruct->color        = &truly_wuxga_video_color;
		panelstruct->videopanel   = &truly_wuxga_video_video_panel;
		panelstruct->commandpanel = &truly_wuxga_video_command_panel;
		panelstruct->state        = &truly_wuxga_video_state;
		panelstruct->laneconfig   = &truly_wuxga_video_lane_config;
		panelstruct->paneltiminginfo
			= &truly_wuxga_video_timing_info;
		panelstruct->panelresetseq
					 = &truly_wuxga_video_panel_reset_seq;
		panelstruct->backlightinfo = &truly_wuxga_video_backlight;
		pinfo->mipi.panel_on_cmds
			= truly_wuxga_video_on_command;
		pinfo->mipi.num_of_panel_on_cmds
			= TRULY_WUXGA_VIDEO_ON_COMMAND;
		pinfo->mipi.panel_off_cmds
			= truly_wuxga_video_off_command;
		pinfo->mipi.num_of_panel_off_cmds
			= TRULY_WUXGA_VIDEO_OFF_COMMAND;
		memcpy(phy_db->timing,
			truly_wuxga_14nm_video_timings, MAX_TIMING_CONFIG * sizeof(uint32_t));
		pinfo->dfps.panel_dfps = truly_wuxga_video_dfps;
		pinfo->mipi.signature 	= TRULY_WUXGA_VIDEO_SIGNATURE;
		break;
case A914_NHD_VIDEO_PANEL:
		panelstruct->paneldata    = &a914_nhd_video_panel_data;
		panelstruct->panelres     = &a914_nhd_video_panel_res;
		panelstruct->color        = &a914_nhd_video_color;
		panelstruct->videopanel   = &a914_nhd_video_video_panel;
		panelstruct->commandpanel = &a914_nhd_video_command_panel;
		panelstruct->state        = &a914_nhd_video_state;
		panelstruct->laneconfig   = &a914_nhd_video_lane_config;
		panelstruct->paneltiminginfo
			= &a914_nhd_video_timing_info;
		panelstruct->panelresetseq
					 = &a914_nhd_video_panel_reset_seq;
		panelstruct->backlightinfo = &a914_nhd_video_backlight;
		pinfo->mipi.panel_on_cmds
			= a914_nhd_video_on_command;
		pinfo->mipi.num_of_panel_on_cmds
			= A914_NHD_VIDEO_ON_COMMAND;
		pinfo->mipi.panel_off_cmds
			= a914_nhd_video_off_command;
		pinfo->mipi.num_of_panel_off_cmds
			= A914_NHD_VIDEO_OFF_COMMAND;
		memcpy(phy_db->timing,
			a914_nhd_video_timings, MAX_TIMING_CONFIG * sizeof(uint32_t));
		pinfo->mipi.signature 	= A914_NHD_VIDEO_SIGNATURE;
		break;

6、调整背光：

在gcdb_display_init()函数中有一个函数指针mdss_dsi_bl_enable：
这个函数是用来调整背光的和使能背光的，通过PWM来作用：（具体要看原理图）

static int mdss_dsi_bl_enable(uint8_t enable)
{
	int ret = NO_ERROR;

	ret = panel_backlight_ctrl(enable);
	if (ret)
		dprintf(CRITICAL, "Backlight %s failed
", enable ? "enable" :
							"disable");
	return ret;
}

static uint32_t panel_backlight_ctrl(uint8_t enable)
{
	uint32_t ret = NO_ERROR;
	if (panelstruct.backlightinfo)
		ret = target_backlight_ctrl(panelstruct.backlightinfo, enable);
	return ret;
}

所以bootloader的背光是通过target_backlight_ctrl()控制的，找到该项目的这个函数修改：
wled_backlight_ctrl；

7、更改LCD的参数：

LCD的一些参数：
VBPD(verticalback porch)：表示在一帧图像开始时，垂直同步信号以后的无效的行数。
VFPD(verticalfront porch)：表示在一帧图像结束后，垂直同步信号以前的无效的行数。
VSPW(verticalsync pulse width)：表示垂直同步脉冲的宽度，用行数计算。
HBPD(horizontal back porch)：表示从水平同步信号开始到一行的有效数据开始之间的VCL的个数。
HFPD(horizontal front porch)：表示一行的有效数据结束到下一个水平同步信号开始 之间的VCLK的个数。
HSPW(horizontalsync pulse width)：表示水平同步信号的宽度，用VCLK计算。