主屏通过lt8911exb 将mipi信号转换成EDP信号输出，调试从大的方向上看，主要是两方面，一个是bootloader阶段的lt8911exb初始化，为了让现实过程更完整，需要在lk的display init之前就要将lt8911exb准备好.当lt8911exb准备好后，就可以当lt8911exb不存在，以平时的方式去调试一个屏幕。本次调试lt8911exb 的I2C接到SDM450的I2C3接口上，以下是调试步骤概要
1、原理图的简单分析
2、lt8911exb的初始化
3、bootloader阶段的屏幕调试
4、kernel阶段移植
一、原理图的简单分析
原理图分析这一块，因为涉及到具体的产品，所以这里只是简单的介绍lt8911exb主控的接口
图一
图2
图三
主控部分和I2C上拉，电平转换等都没有贴出来，以下是简单的总结一下LT8911和主控的接口描述
LT8911的mipi输入端和SDM450的主屏(mdss_dsi0)通过4lane连接
LT8911的I2C接口接SDM450的I2C3
LT8911的上电使能管脚(LCDO_PWR)接SDM450的GPIO19
LT8911的reset管脚(LCD0_RST)接SDM450的GPIO61
屏幕的上电使能(LCD0_EN)接SDM450的GPIO24
屏幕的背光使能(EDP_BL_EN)接SDM450的GPIO44
屏幕的背光接(EDP_BL_PWM)接SDM450主屏PWM
LT8911和屏幕通过2lane连接
LT8911七位I2C地址是0x29
对于LT8911的操作主要是上电、复位、初始化，对于屏幕来说就是上电是能、背光控制
二、lt8911exb初始化
主屏幕的lt8911exb初始化放在bootloader完成，由于SDM450的bootloader阶段I2C接口还没做初始化，所以我们得先初始化好I2C后，再初始化lt8911，具体过程如下
1、SDM450bootloader阶段I2C3初始化
I2C3时钟初始化
bootable/bootloader/lk/platform/msm8953/include/platform/iomap.h
+#define BLSP_QUP_BASE(blsp_id, qup_id) (PERIPH_SS_BASE + 0xB5000 + 0x1000 * qup_id)
+#define GCC_BLSP1_QUP3_APPS_CBCR (CLK_CTL_BASE + 0x04020)
+#define GCC_BLSP1_QUP3_CMD_RCGR (CLK_CTL_BASE + 0x04000)
+#define GCC_BLSP1_QUP3_CFG_RCGR (CLK_CTL_BASE + 0x04004)
bootable/bootloader/lk/platform/msm8953/msm8953-clock.c
+static struct clk_freq_tbl ftbl_gcc_blsp1_qup3_i2c_apps_clk_src[] =
+{
+ F( 96000, cxo, 10, 1, 2),
+ F( 4800000, cxo, 4, 0, 0),
+ F( 9600000, cxo, 2, 0, 0),
+ F( 16000000, gpll0, 10, 1, 5),
+ F( 19200000, gpll0, 1, 0, 0),
+ F( 25000000, gpll0, 16, 1, 2),
+ F( 50000000, gpll0, 16, 0, 0),
+ F_END
+};
+static struct rcg_clk gcc_blsp1_qup3_i2c_apps_clk_src =
+{
+ .cmd_reg = (uint32_t *) GCC_BLSP1_QUP3_CMD_RCGR,
+ .cfg_reg = (uint32_t *) GCC_BLSP1_QUP3_CFG_RCGR,
+ .set_rate = clock_lib2_rcg_set_rate_hid,
+ .freq_tbl = ftbl_gcc_blsp1_qup3_i2c_apps_clk_src,
+ .current_freq = &rcg_dummy_freq,
+
+ .c = {
+ .dbg_name = "gcc_blsp1_qup3_i2c_apps_clk_src",
+ .ops = &clk_ops_rcg,
+ },
+};
+static struct branch_clk gcc_blsp1_qup3_i2c_apps_clk = {
+ .cbcr_reg = (uint32_t *)GCC_BLSP1_QUP3_APPS_CBCR,
+ .parent = &gcc_blsp1_qup3_i2c_apps_clk_src.c,
+
+ .c = {
+ .dbg_name = "gcc_blsp1_qup3_i2c_apps_clk",
+ .ops = &clk_ops_branch,
+ },
+};
static struct rcg_clk sdcc2_apps_clk_src ={
........
+ CLK_LOOKUP("blsp1_ahb_clk", gcc_blsp1_ahb_clk.c),
+ CLK_LOOKUP("gcc_blsp1_qup3_i2c_apps_clk_src", gcc_blsp1_qup3_i2c_apps_clk_src.c),
+ CLK_LOOKUP("gcc_blsp1_qup3_i2c_apps_clk", gcc_blsp1_qup3_i2c_apps_clk.c),
}
//实现时钟配置函数
bootable/bootloader/lk/platform/msm8953/include/platform/clock.h
void clock_config_blsp_i2c(uint8_t blsp_id, uint8_t qup_id);
bootable/bootloader/lk/platform/msm8953/acpuclock.c
#include <blsp_qup.h>
void clock_config_blsp_i2c(uint8_t blsp_id, uint8_t qup_id)
{
uint8_t ret = 0;
char clk_name[64];
struct clk *qup_clk;
if((blsp_id != BLSP_ID_1) || (qup_id > QUP_ID_5)) {
dprintf(CRITICAL, "Incorrect BLSP-%d or QUP-%d configuration\n", blsp_id, qup_id);
ASSERT(0);
}
snprintf(clk_name, sizeof(clk_name), "blsp1_ahb_clk");
ret = clk_get_set_enable(clk_name, 0 , 1);
if (ret) {
dprintf(CRITICAL, "Failed to enable %s clock\n", clk_name);
return;
}
snprintf(clk_name, sizeof(clk_name), "gcc_blsp1_qup3_i2c_apps_clk");
qup_clk = clk_get(clk_name);
if (!qup_clk) {
dprintf(CRITICAL, "Failed to get %s\n", clk_name);
return;
}
ret = clk_enable(qup_clk);
if (ret) {
dprintf(CRITICAL, "Failed to enable %s\n", clk_name);
return;
}
}2、SDM450 I2C3管脚复用功能配置接口实现
bootable/bootloader/lk/platform/msm8953/include/platform/gpio.h
+void gpio_config_blsp_i2c(uint8_t blsp_id, uint8_t qup_id);
bootable/bootloader/lk/platform/msm8953/gpio.c
void gpio_config_blsp_i2c(uint8_t blsp_id, uint8_t qup_id)
{
if(blsp_id == BLSP_ID_1) {
switch (qup_id) {
case QUP_ID_2:
/* configure I2C SDA gpio */
/*
1 arg: GPIO #
2 arg: GPIO Function (Check GPIO MAP)
3 arg: Doesn't matter
4 arg: Should be GPIO_NO_PULL
5 arg: Drive Strength: Lower the better
6 arg: doesn't matter
/* configure I2C SDA gpio */
gpio_tlmm_config(10, 2, GPIO_OUTPUT, GPIO_NO_PULL,
GPIO_8MA, GPIO_DISABLE);
/* configure I2C SCL gpio */
gpio_tlmm_config(11, 2, GPIO_OUTPUT, GPIO_NO_PULL,
GPIO_8MA, GPIO_DISABLE);
break;
case QUP_ID_1:
/* configure I2C SDA gpio */
/*
1 arg: GPIO #
2 arg: GPIO Function (Check GPIO MAP)
3 arg: Doesn't matter
4 arg: Should be GPIO_NO_PULL
5 arg: Drive Strength: Lower the better
6 arg: doesn't matter
*/
/* configure I2C SDA gpio */
gpio_tlmm_config(6, 3, GPIO_OUTPUT, GPIO_NO_PULL,
GPIO_8MA, GPIO_DISABLE);
/* configure I2C SCL gpio */
gpio_tlmm_config(7, 3, GPIO_OUTPUT, GPIO_NO_PULL,
GPIO_8MA, GPIO_DISABLE);
break;
default:
dprintf(CRITICAL, "Incorrect QUP id %d\n",qup_id);
ASSERT(0);
};
} else {
dprintf(CRITICAL, "Incorrect BLSP id %d\n",blsp_id);
ASSERT(0);
}
}3、配置I2C3控制器的内部中断
bootable/bootloader/lk/platform/msm8953/include/platform/irqs.h
+#define BLSP_QUP_IRQ(blsp_id, qup_id) (GIC_SPI_START + 95 + qup_id)4、实现I2C3接口的配置函数(这里其实是bootloader自带的)
bootable/bootloader/lk/platform/msm_shared/mipi_dsi_i2c.c
int mipi_dsi_i2c_device_init(uint8_t blsp_id, uint8_t qup_id)
{
i2c_dev = qup_blsp_i2c_init(blsp_id, qup_id,
I2C_CLK_FREQ, I2C_SRC_CLK_FREQ);
if(!i2c_dev) {
dprintf(CRITICAL, "mipi_dsi_i2c_device_init() failed\n");
return ERR_NOT_VALID;
}
return NO_ERROR;
}
bootable/bootloader/lk/platform/msm_shared/i2c_qup.c
struct qup_i2c_dev *qup_blsp_i2c_init(uint8_t blsp_id, uint8_t qup_id,
uint32_t clk_freq, uint32_t src_clk_freq)
{
struct qup_i2c_dev *dev;
if (dev_addr != NULL) {
return dev_addr;
}
dev = malloc(sizeof(struct qup_i2c_dev));
if (!dev) {
return NULL;
}
dev = memset(dev, 0, sizeof(struct qup_i2c_dev));
/* Platform uses BLSP */
dev->qup_irq = BLSP_QUP_IRQ(blsp_id, qup_id);
dev->qup_base = BLSP_QUP_BASE(blsp_id, qup_id);
/* This must be done for qup_i2c_interrupt to work. */
dev_addr = dev;
/* Initialize the GPIO for BLSP i2c */
gpio_config_blsp_i2c(blsp_id, qup_id);
clock_config_blsp_i2c(blsp_id, qup_id);
qup_i2c_sec_init(dev, clk_freq, src_clk_freq);
return dev;
}5、将i2c_qup.c 和mipi_dsi_i2c.c
bootable/bootloader/lk/platform/msm_shared/rules.mk
+ $(LOCAL_DIR)/i2c_qup.o \
+ $(LOCAL_DIR)/mipi_dsi_i2c.o6、初始化lt8911exb, 这部分只贴出大概架构，其他的没贴出来
bootable/bootloader/lk/include/target.h
定义lt8911exb_config
void lt8911exb_config(void);
bootable/bootloader/lk/app/aboot/aboot.c
在aboot init中添加lt8911的初始化
void aboot_init(const struct app_descriptor *app)
{
..........
lt8911exb_config();
..........
}
bootable/bootloader/lk/target/msm8953/lt8911exb_config.c
void lt8911exb_config(void)
{
lt8911exb_reset();
mipi_dsi_i2c_device_init(BLSP_ID_1, QUP_ID_2);
mdelay(50);
lt8911exb_read_chip_id();
lt8911exb_edp_video_cfg();
lt8911exb_init();
Read_DPCD010A = dpcd_read( 0x010A ) & 0x01;
if( Read_DPCD010A )
{
ScrambleMode = 1;
}else
{
ScrambleMode = 0;
}
lt8911exb_link_train( );
lt8911exb_tx_swing_pre_set( );
lcd_and_bl_power_on();
}三、bootloader阶段的屏幕调试
1、添加屏幕信息头文件，这个不详细介绍如何生成文件
bootable/bootloader/lk/dev/gcdb/display/include/panel_pt156fhm_n10_1080p_video.h
2、修改bootable/bootloader/lk/target/msm8953/oem_panel.c文件进行屏幕的添加
bootable/bootloader/lk/target/msm8953/oem_panel.c
+#include "panel_pt156fhm_n10_1080p_video.h"
enum {
+PB156FHM_N10_800P_VIDEO_PANEL,
}
static struct panel_list supp_panels[] = {
+{"pt156fnm_n10_1080p_video", PB156FHM_N10_800P_VIDEO_PANEL},
}
static int init_panel_data(struct panel_struct *panelstruct,
struct msm_panel_info *pinfo,
struct mdss_dsi_phy_ctrl *phy_db)
{
case PB156FHM_N10_800P_VIDEO_PANEL:
panelstruct->paneldata = &pt156fhm_n10_1080p_video_panel_data;
panelstruct->panelres = &pt156fhm_n10_1080p_video_panel_res;
panelstruct->color = &pt156fhm_n10_1080p_video_color;
panelstruct->videopanel =
&pt156fhm_n10_1080p_video_video_panel;
panelstruct->commandpanel =
&pt156fhm_n10_1080p_video_command_panel;
panelstruct->state = &pt156fhm_n10_1080p_video_state;
panelstruct->laneconfig =
&pt156fhm_n10_1080p_video_lane_config;
panelstruct->paneltiminginfo
= &pt156fhm_n10_1080p_video_timing_info;
panelstruct->panelresetseq
= &pt156fhm_n10_1080p_video_reset_seq;
panelstruct->backlightinfo = &pt156fhm_n10_1080p_video_backlight;
pinfo->mipi.panel_on_cmds
= pt156fhm_n10_1080p_video_on_command;
pinfo->mipi.num_of_panel_on_cmds
= PT156FHM_N10_1080P_VIDEO_OFF_COMMAND;
pinfo->mipi.panel_off_cmds
= pt156fhm_n10_1080p_video_off_command;
pinfo->mipi.num_of_panel_off_cmds
= PT156FHM_N10_1080P_VIDEO_OFF_COMMAND;
memcpy(phy_db->timing,
pt156fhm_n10_14nm_1080p_video_timings, MAX_TIMING_CONFIG * sizeof(uint32_t));
pinfo->mipi.signature = PT156FHM_N10_1080P_VEDIO_SIGNATURE;
break;
}
int oem_panel_select(const char *panel_name, struct panel_struct *panelstruct,
struct msm_panel_info *pinfo,
struct mdss_dsi_phy_ctrl *phy_db)
{
case HW_PLATFORM_RCM:
panel_id = PB156FHM_N10_800P_VIDEO_PANEL;
}四、kernel阶段移植
1、添加屏幕的dtsi文件，具体怎么生成这个文件，不做讲解
kernel/msm-4.9/arch/arm64/boot/dts/qcom/dsi-panel-pt156fnm-n10-1080p-video.dtsi
2、增加这款屏幕支持
kernel/msm-4.9/arch/arm64/boot/dts/qcom/msm8953-mdss-panels.dtsi
+#include "dsi-panel-pt156fnm-n10-1080p-video.dtsi"
kernel/msm-4.9/arch/arm64/boot/dts/qcom/msm8953-nopmi-panel-camera.dtsi
五、调试总结
在调试过程中，注意事项：
1、LT8911的地址，在调试过程中先保证出彩条，确认后级电路没问题
2、LT8911的复位时，reset管脚的高低高输出
3、LT8911和主控mipi端接口是几lane
4、LT8911和屏幕的接口是几lane
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