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内存泄漏系列专题分析之三十二：高通相机CamX ION/dmabuf内存管理机制CmdBuffer

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上一篇我们讲了：

这一篇我们开始讲： 内存泄漏系列专题分析之三十二：高通相机CamX ION/dmabuf内存管理机制CmdBuffer

一、背景

二、：CmdBufferManager管理单元

2.1：CmdBufferManager初始化

2.2：CmdBufferManager获取buffer

三、：Camx CmdBuffer模块

3.1：CmdBuffer初始化

3.2 ：CmdBuffer核心接口

3.3 ：CmdBuffer核心接口使用方式

3.4 ：CmdBuffer中sensor上电命令形式

四、：总结

一、背景

Camx HAL层ION Buffer可以分为两类：ImageBuffer和CmdBuffer。这篇博文就CmdBuffer模块进行分析介绍。

了解过高通Camx架构，一般知道bringup的开发并非都在kernel层，chi-cdk用户态也存在大量bringup开发工作，而用户态sensor等xml配置类似内核态dts配置一样，chi-cdk用户态存在大量sensor、马达等硬件bringup代码，需要讲xml配置通过CmdBuffer的方式下发到kernel去执行最终的驱动代码。

二、：CmdBufferManager管理单元

2.1：CmdBufferManager初始化

CmdBufferManager::Initialize是对CmdBufferManager进行初始化，可以看到核心代码只有一行：可以知道最终还是同ImageBuffer一样由CSLAlloc分配ION内存。

X:\bruce\SI\camx\src\core\camxcmdbuffermanager.cppCamxResult CmdBufferManager::Initialize(const CHAR*             pBufferManagerName,const ResourceParams*   pParams)
{{CAMX_ASSERT(NULL != pBufferManagerName);OsUtils::StrLCpy(m_pBufferManagerName, pBufferManagerName, sizeof(m_pBufferManagerName));m_params         = *pParams;result = InitializePool();}m_pLock = Mutex::Create("CmdBufferManager");return result;
}CamxResult CmdBufferManager::InitializePool()
{CamxResult result = CamxResultSuccess;CAMX_ASSERT((0 != m_params.resourceSize) && (0 == (m_params.poolSize % m_params.resourceSize)));if ((0 == m_params.resourceSize) || (0 != (m_params.poolSize % m_params.resourceSize))){result = CamxResultEInvalidArg;}else{SIZE_T  allocationSize  = 0;UINT32  flags           = m_params.memFlags;m_numResources          = m_params.poolSize / m_params.resourceSize;CSLBufferInfo*  pBufferInfo = static_cast<CSLBufferInfo*>(CAMX_CALLOC(sizeof(CSLBufferInfo)));if (NULL == m_pParentBufferManager){if (NULL != pBufferInfo){result = CSLAlloc(m_pBufferManagerName,pBufferInfo,allocationSize,m_params.alignment,flags,m_params.pDeviceIndices,m_params.numDevices);}}
}

2.2：CmdBufferManager获取buffer

CmdBufferManager获取buffer主要通过GetBuffer和GetBufferForRequest两个接口，返回都是PacketResource，它对应的就是CmdBuffer中CSLBufferInfo，本质就是xml的命令配置。
CmdBufferManager是管理 CmdBuffer的，CmdBufferManager中有2条链表 m_busyPool和m_freePool，其中：m_freePool中存放着空闲的Buffer，m_busyPool中存放着正在被client 使用的Buffer。

CamxResult CmdBufferManager::GetBuffer(PacketResource** ppBuffer)
{LDLLNode* pNode = m_freePool.RemoveFromHead();if (NULL != pNode){*ppBuffer = static_cast<PacketResource*>(pNode->pData);if (NULL == *ppBuffer){result = CamxResultEInvalidState;}else{// Check canaryif (TRUE == (*ppBuffer)->GetUsageFlags().batchedPacket){BatchedPacket* pBatchedPacket = static_cast<BatchedPacket*>(*ppBuffer);pBatchedPacket->CheckCanary();}(*ppBuffer)->Reset();(*ppBuffer)->SetRequestId(CamxInvalidRequestId);}CAMX_FREE(pNode);}m_pLock->Unlock();return result;
}////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
/// CmdBufferManager::GetBufferForRequest
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
CamxResult CmdBufferManager::GetBufferForRequest(UINT64           requestId,PacketResource** ppBuffer)
{CamxResult result = GetBuffer(ppBuffer);m_pLock->Lock();if (CamxResultSuccess == result){CAMX_ASSERT(NULL != *ppBuffer);(*ppBuffer)->SetRequestId(requestId);LDLLNode* pNode = static_cast<LDLLNode*>(CAMX_CALLOC(sizeof(LDLLNode)));if (NULL != pNode){pNode->pData = *ppBuffer;m_busyPool.InsertToTail(pNode);m_peakNumResourcesUsed = Utils::MaxUINT(m_peakNumResourcesUsed, m_busyPool.NumNodes());}else{result = CamxResultENoMemory;}}m_pLock->Unlock();return result;
}

三、：Camx CmdBuffer模块

3.1：CmdBuffer初始化

CmdBuffer初始化本质是对PacketResource进行初始化，再对CSLBufferInfo进行封装。

X:\bruce\SI\camx\src\core\camxcmdbuffer.cppCamxResult CmdBuffer::Initialize(const CmdParams*        pParams,const CSLBufferInfo*    pBufferInfo,SIZE_T                  offset,SIZE_T                  size)
{if (NULL == pParams){CAMX_LOG_ERROR(CamxLogGroupUtils, "Invalid input params");return CamxResultEInvalidPointer;}CamxResult result = PacketResource::Initialize(pBufferInfo, offset, size);return result;
}CamxResult PacketResource::Initialize(const CSLBufferInfo*    pBufferInfo,SIZE_T                  offset,SIZE_T                  size)
{CamxResult result = CamxResultSuccess;if ((NULL == pBufferInfo) || (CSLInvalidHandle == pBufferInfo->hHandle)){result = CamxResultEInvalidArg;CAMX_LOG_ERROR(CamxLogGroupUtils, "Invalid packet initialization args");}else{m_bufferInfo    = *pBufferInfo;m_offsetInBytes = offset;m_sizeInBytes   = size;m_pUserdata     = NULL;m_requestId     = CamxInvalidRequestId;}return result;
}

3.2 ：CmdBuffer核心接口

CmdBuffer核心接口主要是这三个：

CmdBuffer::BeginCommands：CSL开始准备下发命令到kernel
CmdBuffer::CommitCommands：CSL正式提交命令到kernel
CmdBuffer::CancelCommands：CSL取消下发命令到kernel

VOID* CmdBuffer::BeginCommands(UINT32 numDwordsToReserve)
{VOID* pDwords = NULL;if ((GetNumDwordsAvailable() >= numDwordsToReserve) && (0 != numDwordsToReserve)){pDwords = GetCurrentWriteAddr();m_pendingDwords = numDwordsToReserve;// Put a canary to check in commit for overrun// This requires that we allocate one extra dword for command buffers (in command buffer manager)*static_cast<UINT*>(Utils::VoidPtrInc(pDwords, numDwordsToReserve * sizeof(UINT32))) = CamxCanary;}else{CAMX_LOG_ERROR(CamxLogGroupUtils, "Failed to reserve words-Dwords needed:%d, Dwords Available:%d",numDwordsToReserve,GetNumDwordsAvailable());}return pDwords;
}////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
/// CmdBuffer::CommitCommands
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
CamxResult CmdBuffer::CommitCommands()
{CamxResult result = CamxResultSuccess;CAMX_ASSERT_MESSAGE(GetNumDwordsAvailable() >= m_pendingDwords,"Pending dwords: %d to commit is greater than available dwords: %d",m_pendingDwords, GetNumDwordsAvailable());if (0 >= m_pendingDwords){CAMX_LOG_ERROR(CamxLogGroupUtils, "Invalid Command buffer state pending dwords: %d",m_pendingDwords);result = CamxResultEInvalidState;}else{// check for overrunCAMX_ASSERT(CamxCanary == *static_cast<UINT*>(Utils::VoidPtrInc(GetCurrentWriteAddr(),m_pendingDwords * sizeof(UINT32))));m_resourceUsedDwords += m_pendingDwords;m_pendingDwords = 0;}return result;
}////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
/// CmdBuffer::CancelCommands
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
CamxResult CmdBuffer::CancelCommands()
{CamxResult result = CamxResultSuccess;m_pendingDwords = 0;return result;
}

3.3 ：CmdBuffer核心接口使用方式

下面就是OIS和马达bingup代码通过这些接口下发xml命令到kernel

camx/src/swl/sensor/camxois.cpp
result = m_pI2CInfoCmdBuffer->CommitCommands(); in CreateInitializePacket()
result = m_pPowerCmdBuffer->CommitCommands(); in CreateInitializePacket()
result = m_pPowerCmdBuffer->CommitCommands(); in CreateInitializePacket()
result = m_pInitializeCmdBuffer->CommitCommands(); in CreateInitializePacket()
result = pCalibrateCmdBuffer->CommitCommands(); in CreateInitializePacket()
result = pOisModeCmdBuffer->CommitCommands(); in ConfigureOISMode()camx/src/swl/sensor/camxactuator.cpp
result = pI2CInfoCmdBuffer->CommitCommands(); in CreateInitializePacket()
result = pPowerCmdBuffer->CommitCommands(); in CreateInitializePacket()
result = pPowerCmdBuffer->CommitCommands(); in CreateInitializePacket()
result = pInitializeCmdBuffer->CommitCommands(); in CreateInitializePacket()
result = pMoveFocusCmdBuffer->CommitCommands(); in MoveFocus()camx/src/swl/sensor/camxactuator.cpp
CmdBuffer* pInitializeCmdBuffer = NULL; in CreateInitializePacket() local
pInitializeCmdBuffer = m_pParentNode->GetCmdBuffer(m_pInitializeCmdManager); in CreateInitializePacket()
(NULL == pInitializeCmdBuffer)) in CreateInitializePacket()
pInitializeCmdBuffer); in CreateInitializePacket()
pCmdBegin = pInitializeCmdBuffer->BeginCommands(initializeCmdSize / sizeof(UINT32)); in CreateInitializePacket()
result = pInitializeCmdBuffer->CommitCommands(); in CreateInitializePacket()
result = pPacket->AddCmdBufferReference(pInitializeCmdBuffer, NULL); in CreateInitializePacket()
m_pInitializeCmdManager->Recycle(pInitializeCmdBuffer); in CreateInitializePacket()

3.4 ：CmdBuffer中sensor上电命令形式

以下就是imxxxx_sensor.xml配置的sensor上电的时序，最终会通过代码读取并封装到PacketResource打包成CmdBuffer，再下发大kernel。【camx chi bringup解析xml并下发kernel后面单独介绍，流程漫长】

    <powerUpSequence><!--Power setting configurationContains: configType, configValue and delay in milli seconds --><powerSetting><!--Power configuration typeSupported types are: MCLK, VANA, VDIG, VIO, VAF, RESET, STANDBY --><configType>RESET</configType><!--Configuration value for the type of configuration --><configValue>0</configValue><!--Delay in milli seconds --><delayMs>1</delayMs></powerSetting><!--Power setting configurationContains: configType, configValue and delay in milli seconds --><powerSetting><configType>VANA</configType><configValue>0</configValue><delayMs>1</delayMs></powerSetting><powerSetting><configType>VDIG</configType><configValue>0</configValue><delayMs>1</delayMs></powerSetting><powerSetting><configType>VIO</configType><configValue>0</configValue><delayMs>0</delayMs></powerSetting><powerSetting><configType>MCLK</configType><configValue>24000000</configValue><delayMs>1</delayMs></powerSetting><powerSetting><configType>RESET</configType><configValue>1</configValue><delayMs>18</delayMs></powerSetting></powerUpSequence>

四、：总结

Camx CmdBufferManager和CmdBuffer之间的核心关系如上所述：CmdBufferManager通过GetBuffer的有2条链表 m_busyPool和m_freePool拿到CmdBuffer。

CmdBuffer核心接口主要是这三个：

CmdBuffer::BeginCommands：CSL开始准备下发命令到kernel
CmdBuffer::CommitCommands：CSL正式提交命令到kernel
CmdBuffer::CancelCommands：CSL取消下发命令到kernel

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