高通平台MSM8916LCM模块移植（一）-bootloader部分

此次移植打算分成两个模块来说，bootloader部分和kernel部分。在实际的移植调试过程中也是这么分成了两个部分分别调试。

           高通平台中的bootloader叫做LK（Little Kernel,对于LCM来说LK部分相当重要，它不仅要负责开机部分的LCD显示任务，还要负责传参给kernel的LCM驱动，指导kernel选择合适的LCM参数。

1、LK中LCM启动流程

注：read_panel_id()和read_panel_id_ddr3()为私有添加，非高通库上代码。

在这个流程图中，需要着重了解的有oem_panel_select() mdss_dsi_initialize() 和read_panel_id()函数，这三个函数主要是做lcd兼容，下面来具体看函数内容。

2、oem_panel_select()

这个函数在 android/bootloader/lk/target/msm8916/oem_panel.c文件中

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。

/********************************************************
*Name:        oem_panel_select
*Function:    selection different lcm panel
*Description: 1）This func will be roaded twice,first time use default value

                second time depend on lk_lcd_id value match correct branch.
*Author:      Jerry.peng
*********************************************************/
bool oem_panel_select(const char *panel_name, struct panel_struct *panelstruct,
			struct msm_panel_info *pinfo,
			struct mdss_dsi_phy_ctrl *phy_db)
{
	uint32_t soc_version = board_soc_version();
	uint32_t gpio_state = 0;

	gpio_tlmm_config(LCM_GPIO_DETECT, 0, GPIO_INPUT, GPIO_NO_PULL, GPIO_8MA, GPIO_ENABLE)； //这个主要是硬件检测lcd_id引脚，用来区分同一IC不同模组厂屏
	mdelay(10);
	gpio_state = gpio_status(LCM_GPIO_DETECT);
	dprintf(CRITICAL, "[PHC]:oem_panel.c soc_version = 0X%x value,gpio_state=%d\n",soc_version,gpio_state);
			if(0x6089 == lk_lcd_id || 0xFFFF == lk_lcd_id){                       //lk_lcd_id 是自己设定的一个全局变量，赋值在mipi_dsi.c文件中
				if(gpio_state){                                            //这个是同一个IC，不同模组厂的情况，由之前说的lcd_id引脚来判定
					panel_id = ILI9806E_WVGA_VIDEO_HONGTAO_PANEL;
					dprintf(CRITICAL,"[PHC]: ILI9806E hongtao panel choosed\n");
				} else {
					panel_id = ILI9806E_WVGA_VIDEO_HAIFEI_PANEL;
					dprintf(CRITICAL,"[PHC]: ILI9806E haifei panel choosed\n");
				}
			}

			else if(0x8018 == lk_lcd_id){                                     //此处为IC（OTM8019）的情况
				if(gpio_state){
					panel_id = OTM8019_WVGA_VIDEO_SUXIAN_PANEL;
					dprintf(CRITICAL,"[PHC]: otm8019 panel choosed\n");
				} else {
					panel_id = OTM8019_WVGA_VIDEO_HAOSHITONG_PANEL;
					dprintf(CRITICAL,"[PHC]: otm8018b panel choosed\n");
				}
			}

			else if (0x3551 == lk_lcd_id){                               //此处为IC（NT35512S）的情况

					panel_id = NT35512S_WVGA_VIDEO_HAIFEI_PANEL;
					dprintf(CRITICAL,"[PHC]: NT35512S haifei panel choosed\n");
			}
panel_init:
	pinfo->pipe_type = MDSS_MDP_PIPE_TYPE_RGB;
	return init_panel_data(panelstruct, pinfo, phy_db);
}

3、mdss_dsi_initialize()

mdss_dsi_initialize() 在文件android/bootable/bootloader/lk/platform/msm_shared/mipi_dsi.c 中

在 mipi_dsi.c 文件开始先申明全局变量 lk_lcd_id

uint32_t lk_lcd_id = 0xFFFF;

/*****************************************************************
*Name:        mdss_dsi_panel_initialize
*Function:    Read LCM id & send lcm config
*Descritpion: 1/ soc_version use for identify T3F project
              2/ lcm_id_retry usr for identify 2 lane or 4lane mipi
*******************************************************************/
int mdss_dsi_panel_initialize(struct mipi_dsi_panel_config *pinfo, uint32_t
		broadcast)
{
	int status = 0;
	
#if (DISPLAY_TYPE_MDSS == 1)
	if (0xffff == lk_lcd_id ){                                      //洋红色这部分代码是自己添加的和上面函数所说的oem_panel_select（）配合使用
			lk_lcd_id = read_panel_id();                    //此为读ID的函数调用处
		target_force_cont_splash_disable(true);
		msm_display_off();
		target_force_cont_splash_disable(false);
		target_display_init(NULL);                             //从上面流程图看以看出，这个是屏初始化的开始函数，相当于第二次初始化屏幕
		return 1;
	}
	if (pinfo->panel_cmds) {
		if (broadcast) {
			status = mdss_dual_dsi_cmds_tx(pinfo->panel_cmds,
					pinfo->num_of_panel_cmds);

		} else {
			status = mipi_dsi_cmds_tx(pinfo->panel_cmds,
					pinfo->num_of_panel_cmds);
			if (!status && target_panel_auto_detect_enabled())
				status =
					mdss_dsi_read_panel_signature(pinfo->signature);
		}
		dprintf(CRITICAL,"[PHC]: status=%d\n",status);
	}
#endif
	return status;
}

4、read_panel_id()

read_panel_id()为读取LCM ID的函数，里面包括读取各中IC函数，详细看下面代码。

/*****************************************************************
*Name:        read_panel_id
*Function:    Read LCM id
*Descritpion: 1/ lcm_id_retry usr for identify 2 lane or 4lane mipi
              2/ lcm_id_retry == 0 means 2 lane
*Author:      Jerry.peng
*******************************************************************/
uint32_t read_panel_id(void)
{
	uint32_t lcd_id = 0xffff;

 
   
	if( mdss_dsi_read_ili9806e_id() )
		lcd_id = 0x6089;       /* panel ic is ili9806e */
	else if( mdss_dsi_read_otm8018b_id())
		lcd_id = 0x8018;       /* panel ic is otm8018b */
	else if( mdss_dsi_read_nt35512s_id() )
		lcd_id = 0x3551;       /* panel ic is nt35512s */
	if(lcd_id == 0xffff){
		lcd_id = 0x1283;
		dprintf(CRITICAL,"[PHC]: no panel id readed use default \n");
	return lcd_id;
}
 
   
 不同IC的读取ID的函数都大同小异，我这里就用ili9806e这颗IC来举例： 
   
 
   
static struct mipi_dsi_cmd apex_ili9806e_panel_set_cmd[] = {
       {sizeof(apex_ili9806e_cmd0), apex_ili9806e_cmd0},
};

static char apex_ili9806e_panel_set_pkt_size[4] = {0x08, 0x00, 0x37, 0x80};
static struct mipi_dsi_cmd apex_ili9806e_panel_set_pkt_size_cmd[] = {
	{sizeof(apex_ili9806e_panel_set_pkt_size), apex_ili9806e_panel_set_pkt_size},};
static char apex_ili9806e_panel_manufacture_id[4] = {0x00, 0x00, 0x06, 0xA0};
static struct mipi_dsi_cmd apex_ili9806e_panel_manufacture_id_cmd[] = {
	{sizeof(apex_ili9806e_panel_manufacture_id), apex_ili9806e_panel_manufacture_id},};
 
   
 
   
static bool mdss_dsi_read_ili9806e_id(void)
{
	char rec_buf[24];
	char *rp = rec_buf;
	uint32_t *lp,temp,ret, data = 0;


		ret = mipi_dsi_cmds_tx(apex_ili9806e_panel_set_cmd, ARRAY_SIZE(apex_ili9806e_panel_set_cmd));
		mdelay(10);
		ret = mipi_dsi_cmds_tx(apex_ili9806e_panel_set_pkt_size_cmd, ARRAY_SIZE(apex_ili9806e_panel_set_pkt_size_cmd));
		mdelay(10);
		ret = mipi_dsi_cmds_tx(apex_ili9806e_panel_manufacture_id_cmd, ARRAY_SIZE(apex_ili9806e_panel_manufacture_id_cmd));
		mdelay(10);
		if(ret == 1)
			lcm_id_retry += 1;
		mipi_dsi_cmds_rx(&rp, 3);


		lp = (uint32_t *)rp;
		data = (uint32_t)*lp;
		data = ntohl(data);


		data = data & 0xFF;
		dprintf(CRITICAL,"[PHC]: ili9806e id: 0x%x\n", data);
		if(data == 0x98) {
			lcm_id_retry = 0;
			return true;
		}
		else
			return false;
}
 
   
 
   
 
   
       到此，整个lk中LCM兼容和移植的主体部分就已经完成了，剩下就是填LCM参数进.h文件，这里再对整个流程进行一个补充整理。
        首先解释下为什么不用高通默认的兼容方法，因为高通默认的兼容需要用到各种硬件id，平台id，这些都是在SBL中设定的，修改起来麻烦，而且可以兼容的屏幕个数有限，我上面所说的这种方法加上我拓展的一些代码，已经可以兼容十多块屏幕。
 整个兼容方法的思路是，在LCM进行第一遍初始化的时候，什么都不变，但进行到mipi_dsi.c文件中的mdss_dsi_initialize()函数的时候，回去读当前使用的LCM IC 的id
 ，如果和默认的屏幕id一样，则不进行第二次初始化，若不一样，则重新初始化，这个时候全局变量lk_lcd_id已经被赋值，当第二遍初始化到了oem_panel.c文件的oem_panel_select()函数中，函数根据lk_lcd_id的值来匹配正确的屏幕变量。匹配完成之后继续未完成的屏幕初始化，至此整个流程走完，屏幕点亮！
 
   
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