MTK HDMI Driver Process Analysis

chenzq · 发表于 2020-8-15 09:51:59

本帖最后由 chenzq 于 2020-8-15 09:53 编辑

以MT8735 HDMI框架流程做为分析:

一、HDMITX虚拟平台驱动分析：

1、将mtk_extd_mgr_init外部显示管理模块加载到内核中，具体内容见函数分析。

static int __init mtk_extd_mgr_init(void)

{

inti = 0;

intret = 0;

/* structnotifier_block notifier;*/

EXT_MGR_FUNC();

extd_driver[DEV_MHL]= EXTD_HDMI_Driver(); //获得HDMI驱动接口

extd_driver[DEV_EINK]= EXTD_EPD_Driver(); //

extd_factory_driver[DEV_MHL]= EXTD_Factory_HDMI_Driver();

for(i = DEV_MHL; i < DEV_MAX_NUM - 1; i++) {

if(extd_driver->init)

extd_driver->init(); //初始化外部HDMI

}

if(platform_driver_register(&external_display_driver)) { //注册hdmitx驱动到平台中

EXT_MGR_ERR("[EXTD]failedto register mtkfb driver\n");

return-1;

}

notifier.notifier_call= fb_notifier_callback; //fb发生驱动事件的回调函数

ret= fb_register_client(¬ifier); //添加到fb到通知链表中

printk("chenzqmtk_extd_mgr_init ret=%d\n",ret);

if(ret)

EXT_MGR_ERR("unableto register fb callback!\n");

#ifdef CONFIG_HAS_EARLYSUSPEND

register_early_suspend(&extd_early_suspend_handler);

#endif

return0;

}

2、设备与驱动匹配成功之后，调用mtk_extd_mgr_probe函数：主要是注册字符设备，绑定设备号到文件系统中，提供上层控制接口，最后轮询列表，执行hdmi的后初始化。

static int mtk_extd_mgr_probe(structplatform_device *pdev)

{

intret = 0;

inti = 0;

structclass_device *class_dev = NULL;

EXT_MGR_FUNC();

printk("chenzqmtk_extd_mgr_probe \n");

/*Allocate device number for hdmi driver */

ret= alloc_chrdev_region(&extd_devno, 0, 1, EXTD_DEVNAME);

if(ret) {

EXT_MGR_LOG("alloc_chrdev_regionfail\n");

return-1;

}

/*For character driver register to system, device number binded to fileoperations */

extd_cdev= cdev_alloc();

extd_cdev->owner= THIS_MODULE;

extd_cdev->ops= &external_display_fops;

ret= cdev_add(extd_cdev, extd_devno, 1);

/*For device number binded to device name(hdmitx), one class is corresponeded to onenode */

extd_class= class_create(THIS_MODULE, EXTD_DEVNAME);

/*mknod /dev/hdmitx */

class_dev= (struct class_device *)device_create(extd_class, NULL, extd_devno, NULL,EXTD_DEVNAME);

ext_dev_context= (struct device *)&(pdev->dev);

for(i = DEV_MHL; i < DEV_MAX_NUM - 1; i++) {

if(extd_driver->post_init != 0)

extd_driver->post_init();

}

EXT_MGR_LOG("[%s]out\n", __func__);

return0;

}

chenzq · 发表于 2020-8-15 09:52:30

二、MTK HDMI通用驱动详情见kernel-3.18\drivers\misc\mediatek\ext_disp.c，这里只分析部分HDMI的工作流程；

1、 hdmi_init()函数会注册switch设备，该设备用于上报hdmi hotplug事件，hdmires_switch_data用来外部显示数据流的创建；

int hdmi_init(void)

{

intret = 0;

HDMI_ERR("start\n");

/*for support hdmi hotplug, inform AP the event */

hdmi_switch_data.name= "hdmi";

hdmi_switch_data.index= 0;

hdmi_switch_data.state= HDMI_STATE_NO_DEVICE;

ret= switch_dev_register(&hdmi_switch_data);

if(ret)

HDMI_ERR("[hdmi][HDMI]switch_dev_registerfailed, returned:%d!\n", ret);

hdmires_switch_data.name= "res_hdmi";

hdmires_switch_data.index= 0;

hdmires_switch_data.state= 0;

ret= switch_dev_register(&hdmires_switch_data);//接收用来创建外部显示数据路径

if(ret)

HDMI_ERR("[hdmi][HDMI]switch_dev_registerfailed, returned:%d!\n", ret);

HDMI_ERR("done\n");

return0;

}

2、 hdmi_post_init()函数主要是获得HDMI具体IC的驱动接口，HDMI具体IC的初始化。

int hdmi_post_init(void)

{

intboot_mode = 0;

conststruct EXTD_DRIVER *extd_factory_driver = NULL;

staticconst struct HDMI_UTIL_FUNCS hdmi_utils = {

.udelay= hdmi_udelay,

.mdelay= hdmi_mdelay,

.state_callback= hdmi_state_callback,

};

hdmi_drv= (struct HDMI_DRIVER *) HDMI_GetDriver();

if(NULL == hdmi_drv) {

HDMI_ERR("[hdmi]%s,hdmi_init fail, can not get hdmi driver handle\n", __func__);

return-1;

}

hdmi_drv->set_util_funcs(&hdmi_utils);

hdmi_params->init_config.vformat= HDMI_VIDEO_1280x720p_60Hz;

hdmi_drv->get_params(hdmi_params);

hdmi_drv->init(); /* need to remove to power on functionDonglei */

if(hdmi_drv->register_callback != NULL) {

boot_mode= (int)get_boot_mode();

if(boot_mode == FACTORY_BOOT || boot_mode == ATE_FACTORY_BOOT) {

extd_factory_driver= EXTD_Factory_HDMI_Driver();

if(extd_factory_driver)

extd_factory_driver->init();

}else

hdmi_drv->register_callback(hdmi_state_callback);

}

memset((void*)&hdmi_context, 0, sizeof(struct _t_hdmi_context));

memset((void*)&extd_dpi_params, 0, sizeof(extd_dpi_params));

p->output_mode= hdmi_params->output_mode;

SET_HDMI_OFF();

init_waitqueue_head(&hdmi_fence_release_wq);

init_waitqueue_head(&hdmi_vsync_wq);

Extd_DBG_Init();

return0;

}

chenzq · 发表于 2020-8-15 09:54:00

三、HDMI IC的驱动分析，这里用的是lt8618sxb的芯片，具体分析见kernel-3.18\drivers\misc\mediatek\hdmi\lt8618sxb.c。

1、lt8618sxb_init()主要是创建了hdmi的线程和定时器；

static int lt8618sxb_init(void)

{

HDMI_DEF_LOG("lt8618sxb_init\n");

init_waitqueue_head(&hdmi_timer_wq);

hdmi_timer_task= kthread_create(hdmi_timer_kthread, NULL, "hdmi_timer_kthread");

wake_up_process(hdmi_timer_task);

init_waitqueue_head(&lt8618sxb_nlh_wq);

lt8618sxb_nlh_task= kthread_create(lt8618sxb_nlh_kthread, NULL,"lt8618sxb_nlh_kthread");

wake_up_process(lt8618sxb_nlh_task);

memset((void*)&r_hdmi_timer, 0, sizeof(r_hdmi_timer));

r_hdmi_timer.expires= jiffies + 1000 / (1000 / HZ); /*wait 1s to stable */

r_hdmi_timer.function= hdmi_poll_isr;

r_hdmi_timer.data= 0;

init_timer(&r_hdmi_timer);

add_timer(&r_hdmi_timer);

lt8618sxb_hdmi_debug_init();

lt8618sxb_hdmi_factory_callback= NULL;

return0;

}

2、 hdmi_timer_impl()就是在创建的HDMI的线程中调用的，主要是检测hdmi插拔状态（HDMI插拔状态是通过I2C读取IC寄存器的值，在此之前一定要确保I2C是正常通信的），并将插拔的状态上报到switch设备。

void hdmi_timer_impl(void)

{

//HDMI_DEF_LOG("enter%s\n",__func__);

//LT8618SX_Video_check();

//HDMI_DEF_LOG("lt8618sxb_hdmiinit:%d,lt8618sxb_hotinit:%d,lt8618sxb_hotplugstate:

%d\n",lt8618sxb_hdmiinit,lt8618sxb_hotinit,lt8618sxb_hotplugstate);

if(lt8618sxb_hdmiinit == 0) {

lt8618sxb_hdmiinit= 1;

/*lt8618sxb_power_off(); */

//vInitAvInfoVar();

return;

}

if(lt8618sxb_hotinit != 1)

lt8618sxb_hdmiinit++;

#if defined(CONFIG_HAS_EARLYSUSPEND)

if(lt8618sxb_hdmiearlysuspend == 1) {

#else

{

#endif

if(((lt8618sxb_hdmiinit > 5) || (lt8618sxb_hotinit == 0)) &&(lt8618sxb_hotinit != 1)) {

//MT8193_PLUG_LOG("enterhere!\n");

if(bCheckPordHotPlug(PORD_MODE | HOTPLUG_MODE) == FALSE) {

if((lt8618sxb_hotplugstate == HDMI_STATE_HOT_PLUGIN_AND_POWER_ON)

&& (lt8618sxb_hotinit == 2)) {

//vSetSharedInfo(SI_HDMI_RECEIVER_STATUS,HDMI_PLUG_OUT);

lt8618sxb_hotplugstate= HDMI_STATE_HOT_PLUG_OUT;

vPlugDetectService(HDMI_STATE_HOT_PLUG_OUT);

MT8193_PLUG_LOG

("[detectcable1] lt8618sxb_hotinit =%d,lt8618sxb_hdmiinit=%d\n",

lt8618sxb_hotinit, lt8618sxb_hdmiinit);

}

#if 1

if((lt8618sxb_hotinit == 0)

&& (bCheckPordHotPlug(HOTPLUG_MODE)== TRUE)) {

lt8618sxb_hotinit= 2;

lt8618sxb_hotplugstate= HDMI_STATE_HOT_PLUGIN_AND_POWER_ON;

vPlugDetectService(HDMI_STATE_HOT_PLUGIN_AND_POWER_ON);

//vWriteHdmiIntMask(0xff); /* INT mask MDI */

MT8193_PLUG_LOG

("[detectcable2] lt8618sxb_hotinit =%d,lt8618sxb_hdmiinit=%d\n",

lt8618sxb_hotinit, lt8618sxb_hdmiinit);

}

#endif

if((lt8618sxb_hotinit == 0)

&& (bCheckPordHotPlug(HOTPLUG_MODE)== FALSE)) {

lt8618sxb_hotinit= 2;

lt8618sxb_hotplugstate= HDMI_STATE_HOT_PLUG_OUT;

vPlugDetectService(HDMI_STATE_HOT_PLUG_OUT);

MT8193_PLUG_LOG

("[detectcable1] lt8618sxb_hotinit =%d,lt8618sxb_hdmiinit=%d\n",

lt8618sxb_hotinit, lt8618sxb_hdmiinit);

}

}else if ((lt8618sxb_hotplugstate == HDMI_STATE_HOT_PLUG_OUT)

&& (bCheckPordHotPlug(PORD_MODE |HOTPLUG_MODE) == TRUE)) {

lt8618sxb_hotplugstate= HDMI_STATE_HOT_PLUGIN_AND_POWER_ON;

lt8618sxb_hotinit= 2;

vPlugDetectService(HDMI_STATE_HOT_PLUGIN_AND_POWER_ON);

//vWriteHdmiIntMask(0xff); /* INT mask MDI */

MT8193_PLUG_LOG

("[detectcable3] lt8618sxb_hotinit =%d,lt8618sxb_hdmiinit=%d\n",

lt8618sxb_hotinit, lt8618sxb_hdmiinit);

}else if ((lt8618sxb_hotplugstate == HDMI_STATE_HOT_PLUGIN_AND_POWER_ON)

&& ((e_hdcp_ctrl_state ==HDCP_WAIT_RI)

|| (e_hdcp_ctrl_state ==HDCP_CHECK_LINK_INTEGRITY))) {

//MT8193_PLUG_LOG("enter here2!\n");

if(bCheckHDCPStatus(HDCP_STA_RI_RDY)) {

vSetHDCPState(HDCP_CHECK_LINK_INTEGRITY);

vSendHdmiCmd(HDMI_HDCP_PROTOCAL_CMD);

}

lt8618sxb_hdmiinit= 1;

}

if(lt8618sxb_hdmiCmd == HDMI_PLUG_DETECT_CMD) {

vClearHdmiCmd();

/*vcheckhdmiplugstate(); */

/*vPlugDetectService(e_hdmi_ctrl_state); */

}else if (lt8618sxb_hdmiCmd == HDMI_HDCP_PROTOCAL_CMD) {

vClearHdmiCmd();

}

总结：

HDMI工作流程就是linux kernel bootup，加载mtk_extd_mgr_init，获得HDMI驱动接口，匹配成功调用mtk_extd_mgr_probe，初始化hdmi，上层应用检测属性ro.mtk_hdmi_support=1，支持HDMI功能，setting hdmi poweron，底层收到MTK_HDMI_AUDIO_VIDEO_ENABLE将会hdmi_enable()，hdmi_enable()调用hdmi_drv_init()→hdmi_power_on();HDMI进入待机状态，等待hdmi设备的插入。