Android 5.0 Camera系统源码分析：Camera预览3A流程
Posted LittleProgrammer2S
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1. 前言
本文分析的是android Hal层的源码，硬件平台基于mt6735。之前几篇讲的预览流程中3A相关的环节都忽略了，现在重新整理下。
3A指的是Auto Exposure，Auto Focus，Auto White Balance。这三个一起放上来代码实在太多了，这里将重点记录AF的代码。AF的部分工作是由ISP完成的，而ISP的大部分代码mtk都没有开放给我们，比如ISP是如何计算得到对焦位置信息的，但得到对焦位置之后怎么操作对焦马达的代码我们是看得到的，所以涉及到ISP的一些代码将被略过
2. 初始化3A
3A的初始化在DefaultCam1Device的onInit函数里面开始，之前在camera打开流程里面已经提到过
bool
DefaultCam1Device::
onInit()
{
......
// (1) Open 3A
mpHal3a = NS3A::IHal3A::createInstance(
NS3A::IHal3A::E_Camera_1,
getOpenId(),
LOG_TAG);
......
}构造一个Hal3A对象，看下Hal3A::createInstance的实现
Hal3A*
Hal3A::
createInstance(MINT32 i4SensorDevId, MINT32 i4SensorOpenIndex)
{
switch (i4SensorDevId)
{
case SENSOR_DEV_MAIN:
Hal3ADev<SENSOR_DEV_MAIN>::getInstance()->init(i4SensorDevId, i4SensorOpenIndex);
return Hal3ADev<SENSOR_DEV_MAIN>::getInstance();
break;
case SENSOR_DEV_SUB:
Hal3ADev<SENSOR_DEV_SUB>::getInstance()->init(i4SensorDevId, i4SensorOpenIndex);
return Hal3ADev<SENSOR_DEV_SUB>::getInstance();
break;
......
}
}其实这里的Hal3A并没有直接继承IHal3A，也就是说从IHal3A::createInstance到Hal3A::createInstance的调用过程经历了一番波折，但暂时不用关心它。从Hal3A::createInstance可以看到除了实例化以外还会调用init函数。构造函数没什么好看的-略过，直接看init函数
MRESULT
Hal3A::
init(MINT32 i4SensorDevId, MINT32 i4SensorOpenIndex)
{
......
// (1)
mpStateMgr = new StateMgr(i4SensorDevId);
// (2)
bRet = postCommand(ECmd_Init);
// (3)
createThread();
// (4)
bRet = IspTuningMgr::getInstance().init(m_i4SensorDev, m_i4SensorOpenIdx);
// (5)
ret = EnableAFThread(1);
......
return S_3A_OK;
}步骤(1) new StateMgr，构造函数如下
StateMgr::StateMgr(MINT32 sensorDevId)
: ......
{
#define STATE_INITIALIZE(_state_)\\
mpIState[eState_##_state_] = new State##_state_(sensorDevId, this);
STATE_INITIALIZE(Init);
STATE_INITIALIZE(Uninit);
STATE_INITIALIZE(CameraPreview);
STATE_INITIALIZE(CamcorderPreview);
STATE_INITIALIZE(Recording);
STATE_INITIALIZE(Precapture);
STATE_INITIALIZE(Capture);
STATE_INITIALIZE(AF);
mpCurrentState = mpIState[eState_Uninit];
}初始化3A的状态管理，将各个子状态都保存在mpIState数组里面，并将当前状态设置为Uninit状态
步骤(2) postCommand
MBOOL Hal3A::postCommand(ECmd_T const eCmd, MINTPTR const i4Arg)
{
......
ERROR_CHECK(mpStateMgr->sendCmd(eCmd))
......
}MRESULT StateMgr::sendCmd(ECmd_T eCmd)
{
Mutex::Autolock lock(m_Lock);
EIntent_T eNewIntent = static_cast<EIntent_T>(eCmd);
#define SEND_INTENT(_intent_)\\
case _intent_: return mpCurrentState->sendIntent(intent2type<_intent_>());\\
switch (eNewIntent)
{
SEND_INTENT(eIntent_CameraPreviewStart)
SEND_INTENT(eIntent_CameraPreviewEnd)
SEND_INTENT(eIntent_CaptureStart)
SEND_INTENT(eIntent_CaptureEnd)
SEND_INTENT(eIntent_RecordingStart)
SEND_INTENT(eIntent_RecordingEnd)
SEND_INTENT(eIntent_AFUpdate)
SEND_INTENT(eIntent_AFStart)
SEND_INTENT(eIntent_AFEnd)
SEND_INTENT(eIntent_Init)
SEND_INTENT(eIntent_Uninit)
}
return -1;
}从步骤(1)可以看出这里的mpCurrentState指向的是StateUninit对象，所以接着看StateUninit的sendIntent函数
MRESULT
StateUninit::
sendIntent(intent2type<eIntent_Init>)
{
MY_LOG("[StateUninit::sendIntent]<eIntent_Init>");
// AAO DMA buffer init
MINT32 i4SensorIdx = m_pHal3A->getSensorOpenIdx();
if (ENABLE_3A_GENERAL & m_pHal3A->m_3ACtrlEnable) {
if (ENABLE_AAOBUF & m_pHal3A->m_3ACtrlEnable) {
// AAO DMA buffer init
if (!IAAOBufMgr::getInstance().init(m_SensorDevId, i4SensorIdx)) {
MY_ERR("IAAOBufMgr::getInstance().init() fail");
return E_3A_ERR;
}
if (!IAEBufMgr::getInstance().init(m_SensorDevId, i4SensorIdx)) {
MY_ERR("IAEBufMgr::getInstance().init() fail");
return E_3A_ERR;
}
}
if (ENABLE_AFOBUF & m_pHal3A->m_3ACtrlEnable) {
// AFO DMA buffer init
if (!IAFOBufMgr::getInstance().init(m_SensorDevId, i4SensorIdx)) {
MY_ERR("IAFOBufMgr::getInstance().init() fail");
return E_3A_ERR;
}
}
}
// State transition: eState_Uninit --> eState_Init
m_pStateMgr->transitState(eState_Uninit, eState_Init);
return S_3A_OK;
}做了一堆乱七八糟的初始化之后将3A状态从Uninit状态切换到Init状态
步骤(3) createThread和步骤(5) EnableAFThread
MVOID
Hal3A::createThread()
{
......
pthread_create(&mThread, NULL, onThreadLoop, this);
pthread_create(&mPDThread, NULL, PDThreadLoop, this);
pthread_create(&mPDVCThread, NULL, PDVCThreadLoop, this);
......
}MRESULT Hal3A::EnableAFThread(MINT32 a_bEnable)
{
if (a_bEnable) {
if (mbAFThreadLoop== 0)
{
......
pthread_create(&mAFThread, &attr, AFThreadFunc, this);
}
} else {
......
}
return ret;
}一共创建了4个线程，暂时只关心onThreadLoop 和AFThreadFunc。onThreadLoop是3A主线程，负责接收处理命令；AFThreadFunc负责实时更新AF参数
3. 处理PASS1_START_ISP事件
前面的3A初始化做的事情并不多，更多的准备工作是在接收到PASS1_START_ISP事件之后做的，PASS1_START_ISP事件是在之前的Camera预览流程控制流中提到的Pass1Node的startHw函数里面发送
MBOOL
Pass1NodeImpl::
startHw(list<HwPortConfig_t> & plPortCfg)
{
......
handleNotify(PASS1_START_ISP, newMagicNum, 0);
......
}3.1 DefaultCtrlNode接收处理PASS1_START_ISP事件
Pass1Node发出的event将在DefaultCtrlNode的onNotify函数中接收处理
MBOOL
DefaultCtrlNodeImpl::
onNotify(MUINT32 const msg, MUINT32 const ext1, MUINT32 const ext2)
{
switch(msg)
{
case PASS1_START_ISP:
{
if(mpHal3a)
{
cmd = ECmd_CameraPreviewStart;
......
mpHal3a->sendCommand(cmd);
}
case PASS1_STOP_ISP:
{
......
}
case PASS1_EOF:
{
......
}
default:
{
ret = MTRUE;
}
}
return ret;
}Hal3a的sendCommand函数会把命令加入到命令队列，然后由主线程onThreadLoop获取
MVOID*
Hal3A::onThreadLoop(MVOID *arg)
{
while (_this->getCommand(rCmd, bGetCmd, MFALSE))
{
switch (rCmd.eCmd)
{
case ECmd_PrecaptureStart:
{
......
}
case ECmd_Update:
{
......
}
default:
if ( ! _this->postCommand(rCmd.eCmd, reinterpret_cast<MINTPTR>(&rCmd.rParamIspProfile)))
{
MY_ERR("Cmd(%d) failed(0x%x)", rCmd.eCmd, _this->getErrorCode());
AEE_ASSERT_3A_HAL("onThreadLoop postCommand fail(2).");
}
}
}
}onThreadLoop通过getCommand函数获取命令，获取到命令之后调用postCommand函数对命令进行处理
再看一次postCommand
MBOOL Hal3A::postCommand(ECmd_T const eCmd, MINTPTR const i4Arg)
{
if( eCmd == ECmd_CameraPreviewStart || eCmd == ECmd_CaptureStart)
{
mbEnAESenThd = MTRUE;
createAEThread();
mEnFlushVSIrq = mFlushVSIrqDone = 0;
mEnFlushAFIrq = mFlushAFIrqDone = 0;
}
......
ERROR_CHECK(mpStateMgr->sendCmd(eCmd))
......
return MTRUE;
}接收到的命令是ECmd_CameraPreviewStart，所以这里的createAEThread函数会执行
MVOID
Hal3A::createAEThread()
{
pthread_create(&mAESenThread, NULL, AESensorThreadLoop, this);
}加上这个AESensorThreadLoop，需要关注的线程增加到了3个
3.2 StateInit处理CameraPreviewStart命令
继续看mpStateMgr->sendCmd函数。之前介绍过，它会把命令交给当前状态的sendIntent函数进行处理。在初始化阶段已经把当前状态切换到init状态，所以来看StateInit的sendIntent的实现
MRESULT
StateInit::
sendIntent(intent2type<eIntent_CameraPreviewStart>)
{
if (ENABLE_3A_GENERAL & m_pHal3A->m_3ACtrlEnable) {
if (ENABLE_AAOBUF & m_pHal3A->m_3ACtrlEnable) {
// AAO DMAInit + AAStatEnable
if (!IAAOBufMgr::getInstance().DMAInit(m_SensorDevId)) {
MY_ERR("IAAOBufMgr::getInstance().DMAInit() fail");
return E_3A_ERR;
}
if (!IAAOBufMgr::getInstance().AAStatEnable(m_SensorDevId, MTRUE)) {
MY_ERR("IAAOBufMgr::getInstance().AAStatEnable() fail");
return E_3A_ERR;
}
if (!IAEBufMgr::getInstance().DMAInit(m_SensorDevId)) {
MY_ERR("IAEBufMgr::getInstance().DMAInit() fail");
return E_3A_ERR;
}
if (!IAEBufMgr::getInstance().AAStatEnable(m_SensorDevId, MTRUE)) {
MY_ERR("IAEBufMgr::getInstance().AAStatEnable() fail");
return E_3A_ERR;
}
}
if (ENABLE_AFOBUF & m_pHal3A->m_3ACtrlEnable) {
// AFO DMAInit + AFStatEnable
if (!IAFOBufMgr::getInstance().DMAInit(m_SensorDevId)) {
MY_ERR("IAFOBufMgr::getInstance().DMAInit() fail");
return E_3A_ERR;
}
if (!IAFOBufMgr::getInstance().AFStatEnable(m_SensorDevId, MTRUE)) {
MY_ERR("IAFOBufMgr::getInstance().AFStatEnable() fail");
return E_3A_ERR;
}
}
......
if (ENABLE_AWB & m_pHal3A->m_3ACtrlEnable) {
// AWB init
bRet = (m_pHal3A->get3APreviewMode() == EPv_Normal)
? IAwbMgr::getInstance().cameraPreviewInit(m_SensorDevId, i4SensorIdx, rParam)
: IAwbMgr::getInstance().camcorderPreviewInit(m_SensorDevId, i4SensorIdx, rParam);
if (!bRet) {
MY_ERR("IAwbMgr::getInstance().PreviewInit() fail, PvMode = %d\\n", m_pHal3A->get3APreviewMode());
return E_3A_ERR;
}
}
if (ENABLE_AE & m_pHal3A->m_3ACtrlEnable) {
// AE init
err = (m_pHal3A->get3APreviewMode() == EPv_Normal)
? IAeMgr::getInstance().cameraPreviewInit(m_SensorDevId, i4SensorIdx, rParam)
: IAeMgr::getInstance().camcorderPreviewInit(m_SensorDevId, i4SensorIdx, rParam);
if (FAILED(err)) {
MY_ERR("IAeMgr::getInstance().PreviewInit() fail, PvMode = %d\\n", m_pHal3A->get3APreviewMode());
return err;
}
}
if (ENABLE_AF & m_pHal3A->m_3ACtrlEnable) {
// AF init
err = IAfMgr::getInstance().init(m_SensorDevId, i4SensorIdx);
if (FAILED(err)) {
MY_ERR("AfMgr::getInstance().init() fail\\n");
return err;
}
}
IspTuningMgr::getInstance().sendIspTuningIOCtrl(m_SensorDevId, IspTuningMgr::E_ISPTUNING_SET_GMA_SCENARIO, IspTuningMgr::E_GMA_SCENARIO_PREVIEW, 0);
IspTuningMgr::getInstance().sendIspTuningIOCtrl(m_SensorDevId, IspTuningMgr::E_ISPTUNING_NOTIFY_START, 0, 0);
// Reset frame count to -2
m_pStateMgr->resetFrameCount();
// State transition: eState_Init --> eState_CameraPreview
m_pStateMgr->transitState(eState_Init, eState_CameraPreview);
return S_3A_OK;
}包含了AWB、AE、AF在内的ISP相关的初始化，相关的初始化完成之后会调用m_pStateMgr->transitState函数将当前状态切换到CameraPreview状态。
代码太多，这里只关注AF的初始化
MRESULT AfMgr::init(MINT32 i4SensorIdx, MINT32 isInitMCU)
{
......
// --- init MCU ---
SensorStaticInfo rSensorStaticInfo;
if (m_i4EnableAF == -1)
{
IHalSensorList* const pIHalSensorList = IHalSensorList::get();
IHalSensor* pIHalSensor = pIHalSensorList->createSensor("af_mgr", m_i4SensorIdx);
SensorDynamicInfo rSensorDynamicInfo;
switch(m_i4CurrSensorDev)
{
case ESensorDev_Main:
pIHalSensorList->querySensorStaticInfo(NSCam::SENSOR_DEV_MAIN, &rSensorStaticInfo);
pIHalSensor->querySensorDynamicInfo(NSCam::SENSOR_DEV_MAIN, &rSensorDynamicInfo);
break;
case ESensorDev_Sub:
......
default:
MY_ERR("Invalid sensor device: %d", m_i4CurrSensorDev);
}
if(pIHalSensor) pIHalSensor->destroyInstance("af_mgr");
......
m_i4CurrSensorId=rSensorStaticInfo.sensorDevID;
MCUDrv::lensSearch(m_i4CurrSensorDev, m_i4CurrSensorId);
m_i4CurrLensId = MCUDrv::getCurrLensID(m_i4CurrSensorDev);
......
}
if(isInitMCU)
{
m_pMcuDrv = MCUDrv::createInstance(m_i4CurrLensId);
if (m_pMcuDrv->init(m_i4CurrSensorDev) < 0)
{
MY_ERR("m_pMcuDrv->init() fail");
m_i4EnableAF = 0;
}
else
{
m_pMcuDrv->moveMCU( 0, m_i4CurrSensorDev);
m_MoveLensTimeStamp = getTimeStamp();
}
}
// --- init ISP Drv/Reg ---
......
// --- checking PDAF is supported or not ---
......
// --- init af algo ---
......
// --- NVRAM ---
int err;
err = NvBufUtil::getInstance().getBufAndRead(CAMERA_NVRAM_DATA_LENS, m_i4CurrSensorDev, (void*&)g_pNVRAM_LENS);
if(err!=0)
MY_ERR("AfAlgo NvBufUtil get buf fail! \\n");
m_NVRAM_LENS.rFocusRange = g_pNVRAM_LENS->rFocusRange;
m_NVRAM_LENS.rAFNVRAM= g_pNVRAM_LENS->rAFNVRAM;
m_NVRAM_LENS.rPDNVRAM = g_pNVRAM_LENS->rPDNVRAM;
// --- Param ---
m_sAFParam = getAFParam();
m_sAFConfig = getAFConfig();
m_pIAfAlgo->setAFParam(m_sAFParam, m_sAFConfig, m_NVRAM_LENS.rAFNVRAM);
m_pIAfAlgo->initAF(m_sAFInput, m_sAFOutput);
......
m_pIAfAlgo->setAFMode(m_eLIB3A_AFMode);
//init pd mgr
......
return S_AF_OK;
}第30行，调用lensSearch函数匹配镜头驱动
第35-49行，将镜头移动到起始位置
第60-67行，获取af tuning参数
第69-73行，设置af tuning参数
3.3 匹配镜头驱动
MTK为多个镜头做了兼容，所以AF初始化的第一步就是找到当前对应镜头的型号。lensSearch函数实现了lens的匹配过程
int
MCUDrv::lensSearch( unsigned int a_u4CurrSensorDev, unsigned int a_u4CurrSensorId)
{
INT32 i;
LensCustomInit(a_u4CurrSensorDev);
if (a_u4CurrSensorDev == MCU_DEV_MAIN )
{
LensCustomGetInitFunc(&MCUDrv::m_LensInitFunc_main[0]);
MCUDrv::m_u4CurrLensIdx_main = 0;
for (i=0; i<MAX_NUM_OF_SUPPORT_LENS; i++)
{
if ((MCUDrv::m_LensInitFunc_main[i].LensId == DUMMY_LENS_ID) ||
(MCUDrv::m_LensInitFunc_main[i].LensId == SENSOR_DRIVE_LENS_ID) /*||
(MCUDrv::m_LensInitFunc_main[i].LensId == FM50AF_LENS_ID)*/
)
{
MCUDrv::m_u4CurrLensIdx_main = i;
}
}
// force assign LensIdx if SensorId != DUMMY_SENSOR_ID (to support backup lens/new lens driver)
for (i=0; i<MAX_NUM_OF_SUPPORT_LENS; i++)
{
if ((MCUDrv::m_LensInitFunc_main[i].SensorId == a_u4CurrSensorId) && (a_u4CurrSensorId!=0xFFFF) && (a_u4CurrSensorId!=0x0))
{
MCUDrv::m_u4CurrLensIdx_main = i;
MCU_DRV_DBG("[idx]%d [CurrSensorId]0x%04x,[CurrLensIdx]0x%04x\\n", i, a_u4CurrSensorId, MCUDrv::m_u4CurrLensIdx_main);
break;
}
}
LensCustomSetIndex(MCUDrv::m_u4CurrLensIdx_main);
MCU_DRV_DBG("[CurrLensIdx]%d", MCUDrv::m_u4CurrLensIdx_main);
}
else if( a_u4CurrSensorDev == MCU_DEV_SUB)
{
......
}
else
return MCU_INVALID_DRIVER;
return MCU_NO_ERROR;
}先看LensCustomInit函数，由它来获取拷贝整个lens列表
MUINT32 LensCustomInit(unsigned int a_u4CurrSensorDev)
{
GetLensInitFuncList(&LensInitFunc[0], a_u4CurrSensorDev);
return 0;
}UINT32 GetLensInitFuncList(PMSDK_LENS_INIT_FUNCTION_STRUCT pLensList, unsigned int a_u4CurrSensorDev)
{
if(a_u4CurrSensorDev==2) //sub
memcpy(pLensList, &LensList_sub[0], sizeof(MSDK_LENS_INIT_FUNCTION_STRUCT)* MAX_NUM_OF_SUPPORT_LENS);
else if(a_u4CurrSensorDev==4) //main 2
memcpy(pLensList, &LensList_main2[0], sizeof(MSDK_LENS_INIT_FUNCTION_STRUCT)* MAX_NUM_OF_SUPPORT_LENS);
else // main or others
memcpy(pLensList, &LensList_main[0], sizeof(MSDK_LENS_INIT_FUNCTION_STRUCT)* MAX_NUM_OF_SUPPORT_LENS);
return MHAL_NO_ERROR;
}根据前后摄像头拷贝不同的LensList，这里只看其中的LensList_main
MSDK_LENS_INIT_FUNCTION_STRUCT LensList_main[MAX_NUM_OF_SUPPORT_LENS] =
{
{DUMMY_SENSOR_ID, DUMMY_LENS_ID, "Dummy", pDummy_getDefaultData},
#if defined(SENSORDRIVE)
{OV3640_SENSOR_ID, SENSOR_DRIVE_LENS_ID, "kd_camera_hw", pSensorDrive_getDefaultData},
#endif
#if defined(FM50AF)
{DUMMY_SENSOR_ID, FM50AF_LENS_ID, "FM50AF", pFM50AF_getDefaultData},
#endif
#if defined(DW9714AF)
{IMX135_SENSOR_ID, DW9714AF_LENS_ID, "DW9714AF", pDW9714AF_getDefaultData},
#endif
......
};LensList_main包含了后摄所有可用的lens，如果要新增一个lens驱动，就需要往这个数组添加相关的信息，看下MSDK_LENS_INIT_FUNCTION_STRUCT结构体的定义
typedef struct
{
UINT32 SensorId;
UINT32 LensId;
UINT8 LensDrvName[32];
UINT32 (*getLensDefault)(VOID *pDataBuf, UINT32 size);
} MSDK_LENS_INIT_FUNCTION_STRUCT, *PMSDK_LENS_INIT_FUNCTION_STRUCT;SensorId：表示这个lens driver配置给对应的sensor使用，如果配置成DUMMY_SENSOR_ID则表示这个lens driver适合所有sensor使用
LensId：Lens driver的唯一标识
LensDrvName：是实现AF功能的驱动对应的设备驱动节点名。例如FM20AF，实现AF功能的是内核驱动里面的fm20af.c，这个驱动会生成一个驱动节点”/dev/fm20af”
getLensDefault：这个函数指针指向了获取AF tuning参数表的一个函数
回到lensSearch函数，现在lens列表已经保存在LensInitFunc数组中了，接下来调用LensCustomGetInitFunc函数把它拷贝到m_LensInitFunc_main数组中
MUINT32 LensCustomGetInitFunc(MSDK_LENS_INIT_FUNCTION_STRUCT *a_pLensInitFunc)
{
if (a_pLensInitFunc != NULL) {
memcpy(a_pLensInitFunc, &LensInitFunc[0], sizeof(MSDK_LENS_INIT_FUNCTION_STRUCT) * MAX_NUM_OF_SUPPORT_LENS);
return 0;
}
return -1;
}lensSearch函数再接下来就是两个for循环，从m_LensInitFunc_main数组中搜索符合要求的lens驱动
第一个for循环：m_u4CurrLensIdx_main指向m_LensInitFunc_main数组里lensId配置为DUMMY_LENS_ID或SENSOR_DRIVE_LENS_ID的最后一个元素
第二个for循环：查找m_LensInitFunc_main数组中是否有SensorId和当前使用的sensor的ID相匹配的lens driver。如果有则为符合条件的第一个元素，没有的话则为第一个for循环搜索到的结果
最后调用LensCustomSetIndex把匹配到的lens driver的index保存下来
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