目錄
- Camera.open() 流程筆記
- Camera.setPreviewDisplay() 流程筆記
- Camera.startPreview() 流程
-
- m_stateMachine 狀态機分析
- VIDIOC_DQBUF 分析
- 總結
Camera.open() 流程筆記
《Camera.open() 流程》
frameworks/base/core/java/android/hardware/Camera.java
open()
--->return new Camera(cameraId);
--->cameraInitNormal(cameraId);
--->cameraInitVersion(cameraId, CAMERA_HAL_API_VERSION_NORMAL_CONNECT);
--->looper = Looper.myLooper()
--->String packageName = ActivityThread.currentOpPackageName();
--->return native_setup(new WeakReference<Camera>(this), cameraId, halVersion, packageName); //JNI 調用 frameworks/base/core/jni/android_hardware_Camera.cpp 檔案中的 android_hardware_Camera_native_setup 函數
--->const char16_t *rawClientName = reinterpret_cast<const char16_t*>(env->GetStringChars(clientPackageName, NULL));
--->if (halVersion == CAMERA_HAL_API_VERSION_NORMAL_CONNECT)
--->camera = Camera::connect(cameraId, clientName, Camera::USE_CALLING_UID, Camera::USE_CALLING_PID);
--->return CameraBaseT::connect(cameraId, clientPackageName, clientUid, clientPid); //調用到 CameraBase.cpp
--->sp<TCam> c = new TCam(cameraId); // TCam = Camera
--->sp<TCamCallbacks> cl = c;
--->const sp<::android::hardware::ICameraService> cs = getCameraService(); //得到 CameraService
--->TCamConnectService fnConnectService = TCamTraits::fnConnectService; //TCamTraits = CameraTraits<Camera> 在 Camera.cpp 中定義 fnConnectService = &::android::hardware::ICameraService::connect;
--->(cs.get()->*fnConnectService)(cl, cameraId, clientPackageName, clientUid, clientPid, /*out*/ &c->mCamera); //就是調用 CameraService::connect()
--->connectHelper<ICameraClient,Client>(cameraClient, id, CAMERA_HAL_API_VERSION_UNSPECIFIED, clientPackageName, clientUid, clientPid, API_1, false, false,/*out*/client);
--->makeClient(&client, ...)
--->sp<ICameraClient> tmp = static_cast<ICameraClient*>(cameraCb.get());
--->*client = new CameraClient(cameraService, tmp, packageName, cameraIdToInt(cameraId), facing, clientPid, clientUid, getpid(), legacyMode);
--->Client(cameraService, cameraClient, clientPackageName, String8::format("%d", cameraId), cameraFacing, clientPid, clientUid, servicePid)
--->mRemoteCallback = cameraClient;
--->client->initialize(mCameraProviderManager); // mCameraProviderManager 很關鍵，在CameraService::enumerateProviders()中設定
--->CameraClient::initialize(providerPtr)
--->mHardware = new CameraHardwareInterface(camera_device_name);
--->mHardware->initialize(manager);
--->return manager->openSession(mName.string(), this, &mHidlDevice); // manager = CameraProviderManager, this = CameraHardwareInterface , mHidlDevice = CameraDevice
--->CameraProviderManager::openSession(id, callback, session)
--->auto deviceInfo = findDeviceInfoLocked(id, /*minVersion*/ {1,0}, /*maxVersion*/ {2,0});
--->for (auto& provider : mProviders) //輪循 mProviders, 這個很關鍵，看下面 mProviders 相關
--->for (auto& deviceInfo : provider->mDevices) //mDevices 在 addDevice 中設定
--->return deviceInfo.get();
--->auto *deviceInfo1 = static_cast<ProviderInfo::DeviceInfo1*>(deviceInfo);
--->deviceInfo1->mInterface->open(callback); //mInterface 它實際上是 CameraDevice 對象，參考 module 與 CameraDevice 相關
--->CameraDevice::open(callback)
--->mModule->getCameraInfo(mCameraIdInt, &info); //調用hal的get_camera_info函數
--->mModule->open(mCameraId.c_str(), (hw_device_t **)&mDevice); //調用hal的open函數,得到 device 參考《hal 層分析》mDevice = mCameraDevice
--->initHalPreviewWindow(); //填充 preview 相關函數
--->mHalPreviewWindow.cancel_buffer = sCancelBuffer;
--->mHalPreviewWindow.lock_buffer = sLockBuffer;
--->mHalPreviewWindow.dequeue_buffer = sDequeueBuffer;
--->mHalPreviewWindow.enqueue_buffer = sEnqueueBuffer;
--->mHalPreviewWindow.set_buffer_count = sSetBufferCount;
--->mHalPreviewWindow.set_buffers_geometry = sSetBuffersGeometry;
--->mHalPreviewWindow.set_crop = sSetCrop;
--->mHalPreviewWindow.set_timestamp = sSetTimestamp;
--->mHalPreviewWindow.set_usage = sSetUsage;
--->mHalPreviewWindow.set_swap_interval = sSetSwapInterval;
--->mHalPreviewWindow.get_min_undequeued_buffer_count = sGetMinUndequeuedBufferCount;
--->mDeviceCallback = callback;
--->mQDeviceCallback = vendor::qti::hardware::camera::device::V1_0::IQCameraDeviceCallback::castFrom(callback); //vendor 層回調
--->mDevice->ops->set_callbacks(mDevice, sNotifyCb, sDataCb, sDataCbTimestamp, sGetMemory, this); //mDevice 就是由 open HAL 層得到的
--->*session = deviceInfo1->mInterface; // mInterface 就是 CameraDevice 對象
--->mHardware->setCallbacks(notifyCallback, dataCallback, dataCallbackTimestamp, handleCallbackTimestampBatch, (void *)(uintptr_t)mCameraId);
--->mNotifyCb = notify_cb;
--->mDataCb = data_cb;
--->mDataCbTimestamp = data_cb_timestamp;
--->mDataCbTimestampBatch = data_cb_timestamp_batch;
--->mCbUser = user;
--->*device = client;
--->IInterface::asBinder(c->mCamera)->linkToDeath(c); //連接配接死亡通知
--->return c; // c = Camera 對象
--->jclass clazz = env->GetObjectClass(thiz);
--->sp<JNICameraContext> context = new JNICameraContext(env, weak_this, clazz, camera);
--->mCameraJObjectWeak = env->NewGlobalRef(weak_this);
--->mCameraJClass = (jclass)env->NewGlobalRef(clazz);
--->mCamera = camera;
--->context->incStrong((void*)android_hardware_Camera_native_setup);
--->camera->setListener(context);
--->env->SetLongField(thiz, fields.context, (jlong)context.get());
--->CameraInfo cameraInfo;
--->status_t rc = Camera::getCameraInfo(cameraId, &cameraInfo);
--->switch (cameraInfo.orientation) { //Update default display orientation in case the sensor is reverse-landscape
--->case 180:
--->defaultOrientation = 180;
--->camera->sendCommand(CAMERA_CMD_SET_DISPLAY_ORIENTATION, defaultOrientation, 0); //Camera::sendCommand(int32_t cmd, int32_t arg1, int32_t arg2)
--->sp <::android::hardware::ICamera> c = mCamera; // mCamera 就是在 CameraService::connect() 時得到的 CameraClient
--->c->sendCommand(cmd, arg1, arg2); //就是調用 CameraClient::sendCommand(int32_t cmd, int32_t arg1, int32_t arg2)
--->orientation = getOrientation(arg1, mCameraFacing == CAMERA_FACING_FRONT);
--->mOrientation = orientation;
--->if (mPreviewWindow != 0)
--->mHardware->setPreviewTransform(mOrientation); //就是調用 CameraHardwareInterface::setPreviewTransform(int transform)
--->mPreviewTransform = transform;
--->if (mPreviewWindow != nullptr)
--->native_window_set_buffers_transform(mPreviewWindow.get(), mPreviewTransform);
--->window->perform(window, NATIVE_WINDOW_SET_BUFFERS_TRANSFORM, transform);
Camera.setPreviewDisplay() 流程筆記
frameworks/base/core/java/android/hardware/Camera.java
setPreviewDisplay(SurfaceHolder holder)
--->setPreviewSurface(holder.getSurface()); // Jni 調用 android_hardware_Camera_setPreviewSurface(JNIEnv *env, jobject thiz, jobject jSurface)
--->sp<Camera> camera = get_native_camera(env, thiz, NULL);
--->JNICameraContext* context = reinterpret_cast<JNICameraContext*>(env->GetLongField(thiz, fields.context)); //獲得 open 的時候建立的上下文
--->camera = context->getCamera(); //獲得 open 的時候設定的 camera
--->return camera;
--->sp<IGraphicBufferProducer> gbp;
--->sp<Surface> surface;
--->surface = android_view_Surface_getSurface(env, jSurface);
--->sp<Surface> sur;
--->sur = reinterpret_cast<Surface *>(env->GetLongField(surfaceObj, gSurfaceClassInfo.mNativeObject));
--->return sur;
--->gbp = surface->getIGraphicBufferProducer();
--->return mGraphicBufferProducer;
--->camera->setPreviewTarget(gbp)
--->sp <::android::hardware::ICamera> c = mCamera; //mCamera 就是在 CameraService::connect(&mCamera) 時得到的 CameraClient
--->c->setPreviewTarget(bufferProducer); //CameraClient::setPreviewTarget(const sp<IGraphicBufferProducer>& bufferProducer)
--->sp<IBinder> binder;
--->binder = IInterface::asBinder(bufferProducer);
--->window = new Surface(bufferProducer, /*controlledByApp*/ true);
--->return setPreviewWindow(binder, window);
--->native_window_api_connect(window.get(), NATIVE_WINDOW_API_CAMERA);
--->return window->perform(window, NATIVE_WINDOW_API_CONNECT, api); // api = NATIVE_WINDOW_API_CAMERA, 顯示相關的了，不分析
--->disconnectWindow(mPreviewWindow); //斷開舊 mPreviewWindow
--->mSurface = binder;
--->mPreviewWindow = window; //使用新的 mPreviewWindow
Camera.startPreview() 流程
frameworks/base/core/java/android/hardware/Camera.java
startPreview()
--->android_hardware_Camera_startPreview(JNIEnv *env, jobject thiz)
--->sp<Camera> camera = get_native_camera(env, thiz, NULL);
--->JNICameraContext* context = reinterpret_cast<JNICameraContext*>(env->GetLongField(thiz, fields.context)); //獲得 open 的時候建立的上下文
--->camera = context->getCamera(); //獲得 open 的時候設定的 camera
--->return camera;
--->camera->startPreview() //Camera::startPreview()
--->sp <::android::hardware::ICamera> c = mCamera; // mCamera 就是在 CameraService::connect(&mCamera) 時得到的。是以 mCamera = CameraClient(代理類對象)
--->c->startPreview(); // 就是調用 CameraClient::startPreview()
--->return startCameraMode(CAMERA_PREVIEW_MODE);
--->return startPreviewMode();
--->mHardware->setPreviewScalingMode(NATIVE_WINDOW_SCALING_MODE_SCALE_TO_WINDOW); //适配視窗大小
--->mHardware->setPreviewTransform(mOrientation); //設定旋轉方向
--->mHardware->setPreviewWindow(mPreviewWindow); //就是調用 CameraHardwareInterface::setPreviewWindow()
--->mPreviewWindow = buf; // 注意: mPreviewWindow 存在的作用域不一樣。 這裡的是 CameraHardwareInterface::mPreviewWindow 上面是 CameraClient::mPreviewWindow
--->return mHidlDevice->setPreviewWindow(buf.get() ? this : nullptr); //mHidlDevice 是 CameraDevice
--->mHalPreviewWindow.mPreviewCallback = window;
--->mDevice->ops->set_preview_window(mDevice, (window == nullptr) ? nullptr : &mHalPreviewWindow) //mDevice 就是由 open HAL 層得到的 就是調用 QCamera2HardwareInterface::set_preview_window()
--->QCamera2HardwareInterface *hw = reinterpret_cast<QCamera2HardwareInterface *>(device->priv);
--->hw->processAPI(QCAMERA_SM_EVT_SET_PREVIEW_WINDOW, (void *)window);
--->m_stateMachine.procAPI(api, api_payload); //更新狀态機 參考《m_stateMachine 狀态機分析》
--->qcamera_sm_cmd_t *node = (qcamera_sm_cmd_t *)malloc(sizeof(qcamera_sm_cmd_t));
--->node->cmd = QCAMERA_SM_CMD_TYPE_API;
--->node->evt = evt;
--->node->evt_payload = api_payload;
--->api_queue.enqueue((void *)node) //加入隊列
--->cam_sem_post(&cmd_sem); //通知處理線程
--->mHardware->startPreview(); //就是調用 CameraHardwareInterface::startPreview()
--->return mHidlDevice->startPreview(); //mHidlDevice 是 CameraDevice
--->mDevice->ops->start_preview(mDevice) //mDevice 就是由 open HAL 層得到的 就是調用 QCamera2HardwareInterface::start_preview()
--->QCamera2HardwareInterface *hw = reinterpret_cast<QCamera2HardwareInterface *>(device->priv);
--->qcamera_sm_evt_enum_t evt = QCAMERA_SM_EVT_START_PREVIEW;
--->hw->processAPI(evt, NULL);
--->m_stateMachine.procAPI(api, api_payload); //更新狀态機 參考《m_stateMachine 狀态機分析》
--->pme->stateMachine(node->evt, node->evt_payload); //注意：這裡是另一個線程執行的了。 QCameraStateMachine::stateMachine()
--->switch (m_state) {
--->case QCAMERA_SM_STATE_PREVIEW_STOPPED: //這是最初始狀态
--->procEvtPreviewStoppedState(evt, payload);
--->switch (evt) {
--->case QCAMERA_SM_EVT_START_PREVIEW:
--->m_parent->preparePreview(); // m_parent = QCamera2HardwareInterface 對象
--->addChannel(QCAMERA_CH_TYPE_PREVIEW);
--->addPreviewChannel();
--->QCameraChannel *pChannel = NULL;
--->pChannel = new QCameraChannel(handle, mCameraHandle->ops);// mCameraHandle->ops = mm_camera_ops 參考 《hal 層分析》
--->m_camHandle = cam_handle;
--->m_camOps = cam_ops; //m_camOps = mm_camera_ops
--->pChannel->init(NULL, NULL, NULL);
--->m_handle = m_camOps->add_channel(m_camHandle, attr, dataCB, userData); // m_camOps = mm_camera_ops 是以是調用 mm_camera_intf_add_channel()
--->mm_camera_add_channel(my_obj, attr, channel_cb, userdata);
--->ch_obj = &my_obj->ch[ch_idx];
--->mm_channel_init(ch_obj, attr, channel_cb, userdata);
--->mm_camera_poll_thread_launch(&my_obj->poll_thread[0], MM_CAMERA_POLL_TYPE_DATA); //開啟線程，這個線程其中一個作用就是當camera有資料時調用回調
--->poll_cb->pfds[0] = -1;
--->poll_cb->pfds[1] = -1;
--->pipe(poll_cb->pfds);
--->pthread_create(&poll_cb->pid, NULL, mm_camera_poll_thread, (void *)poll_cb); //建立線程
--->return mm_camera_poll_fn(poll_cb);
--->do {
--->poll(poll_cb->poll_fds, poll_cb->num_fds, poll_cb->timeoutms); //poll 等待
--->if ((poll_cb->poll_fds[0].revents & POLLIN) {
--->mm_camera_poll_proc_pipe(poll_cb); //添加 poll fd 走這個分支
--->read(poll_cb->pfds[0], &cmd_evt, sizeof(cmd_evt));
--->poll_cb->poll_fds[poll_cb->num_fds].fd = poll_cb->pfds[0];
--->poll_cb->poll_fds[poll_cb->num_fds].events = POLLIN|POLLRDNORM|POLLPRI;
--->poll_cb->num_fds++;
--->}
--->if ((MM_CAMERA_POLL_TYPE_DATA == poll_cb->poll_type) && (poll_cb->poll_fds[i].revents & POLLIN)) {
--->poll_cb->poll_entries[i-1].notify_cb(poll_cb->poll_entries[i-1].user_data); //camera 有資料走這個分支。參考 《VIDIOC_DQBUF 分析》
--->}
--->addStreamToChannel(pChannel, CAM_STREAM_TYPE_METADATA, metadata_stream_cb_routine, this);
--->addStreamToChannel(pChannel, CAM_STREAM_TYPE_PREVIEW, preview_stream_cb_routine, this);
--->pChannel->addStream(*this, pStreamInfo, NULL, &padding_info, main_cb, userData, bDynAllocBuf, deferAllocation, ROTATE_0, cam_type);
--->QCameraStream *pStream = new QCameraStream(allocator, m_camHandle, ch_handle, m_camOps, paddingInfo, bDeffAlloc, online_rotation);
--->mCamOps(camOps) //mCamOps = mm_camera_ops
--->mMemVtbl.user_data = this;
--->mMemVtbl.get_bufs = get_bufs;
--->mMemVtbl.put_bufs = put_bufs;
--->pStream->init(streamInfoBuf, miscBuf, stream_cb, userdata, bDynAllocBuf); // stream_cb = preview_stream_cb_routine
--->mHandle = mCamOps->add_stream(mCamHandle, mChannelHandle);
--->configStream()
--->stream_config.mem_vtbl = mMemVtbl;
--->stream_config.stream_cb = dataNotifyCB;
--->stream_config.userdata = this;
--->mCamOps->config_stream(mCamHandle, mChannelHandle, mHandle, &stream_config); //mCamOps = mm_camera_ops 是以調用 mm_camera_intf_config_stream
--->my_obj = mm_camera_util_get_camera_by_handler(handle);
--->mm_camera_config_stream(my_obj, chid, strid, config);
--->mm_channel_t * ch_obj = mm_camera_util_get_channel_by_handler(my_obj, ch_id);
--->payload.stream_id = stream_id;
--->payload.config = config;
--->mm_channel_fsm_fn(ch_obj, MM_CHANNEL_EVT_CONFIG_STREAM, (void *)&payload, NULL);
--->mm_channel_fsm_fn_stopped(my_obj, evt, in_val, out_val);
--->mm_evt_paylod_config_stream_t *payload = (mm_evt_paylod_config_stream_t *)in_val;
--->mm_channel_config_stream(my_obj, payload->stream_id, payload->config);
--->mm_stream_t *stream_obj = mm_channel_util_get_stream_by_handler(my_obj, stream_id);
--->mm_stream_fsm_fn(stream_obj, MM_STREAM_EVT_SET_FMT, (void *)config, NULL);
--->mm_stream_fsm_acquired(my_obj, evt, in_val, out_val);
--->mm_camera_stream_config_t *config = (mm_camera_stream_config_t *)in_val;
--->mm_stream_config(my_obj, config);
--->my_obj->buf_cb[cb_index].cb = config->stream_cb; // stream_cb = dataNotifyCB
--->my_obj->buf_cb[cb_index].user_data = config->userdata; // userdata = this
--->my_obj->mem_vtbl = config->mem_vtbl; //mem_vtbl = mMemVtbl
--->mm_stream_set_fmt(my_obj);
--->struct msm_v4l2_format_data msm_fmt;
--->msm_fmt.width = (unsigned int)my_obj->stream_info->dim.width; //設定圖像寬度
--->msm_fmt.height = (unsigned int)my_obj->stream_info->dim.height; //設定圖像高度
--->msm_fmt.pixelformat = mm_stream_get_v4l2_fmt(my_obj->stream_info->fmt); //得到Bpp
--->memcpy(fmt.fmt.raw_data, &msm_fmt, sizeof(msm_fmt));
--->ioctl(my_obj->fd, VIDIOC_S_FMT, &fmt); //設定格式
--->mDataCB = stream_cb; // mDataCB = QCamera2HardwareInterface::preview_stream_cb_routine()
--->mStreams.add(pStream);
--->m_channels[QCAMERA_CH_TYPE_PREVIEW] = pChannel;
--->addChannel(QCAMERA_CH_TYPE_ZSL); //跟上面類似， 不分析
--->m_parent->startPreview(); // m_parent = QCamera2HardwareInterface 對象
--->startChannel(QCAMERA_CH_TYPE_PREVIEW);
--->m_channels[ch_type]->start(); // ch_type = QCAMERA_CH_TYPE_PREVIEW
--->mStreams[i]->start(); //啟動Stream
--->mDataQ.init();
--->mProcTh.launch(dataProcRoutine, this); //開啟線程
--->QCameraStream *pme = (QCameraStream *)data;
--->QCameraCmdThread *cmdThread = &pme->mProcTh;
--->do {
--->cam_sem_wait(&cmdThread->cmd_sem); //等待消息 參考 《VIDIOC_DQBUF 分析》
--->camera_cmd_type_t cmd = cmdThread->getCmd(); //取出消息
--->case CAMERA_CMD_TYPE_DO_NEXT_JOB:
--->mm_camera_super_buf_t *frame = (mm_camera_super_buf_t *)pme->mDataQ.dequeue(); //從隊列中取出一幀
--->pme->mDataCB(frame, pme, pme->mUserData); //就是調用 QCamera2HardwareInterface::preview_stream_cb_routine()
--->QCamera2HardwareInterface *pme = (QCamera2HardwareInterface *)userdata; //userdata = pme->mUserData
--->QCameraGrallocMemory *memory = (QCameraGrallocMemory *)super_frame->bufs[0]->mem_info; //super_frame = frame
--->mm_camera_buf_def_t *dumpBuffer = NULL;
--->mm_camera_buf_def_t *frame = super_frame->bufs[0];
--->uint32_t idx = frame->buf_idx; //取出 buf 索引
--->memory->setBufferStatus(frame->buf_idx, STATUS_ACTIVE);
--->memory->enqueueBuffer(idx); //根據 buf 索引,将buf加入隊列, 這裡就是顯示了
--->mWindow->enqueue_buffer(mWindow, (buffer_handle_t *)mBufferHandle[index]); //mWindow = mHalPreviewWindow 顯示相關不分析
--->stream->bufDone((uint32_t)dequeuedIdx); //釋放buf Return dequeued buffer back to driver
--->mCamOps->qbuf(mCamHandle, mChannelHandle, &mBufDefs[index]); // mCamOps = mm_camera_ops 是以調用 mm_camera_intf_qbuf()
--->strid = get_main_camera_handle(buf->stream_id);
--->my_obj = mm_camera_util_get_camera_by_handler(handle);
--->mm_camera_qbuf(my_obj, chid, buf);
--->ch_obj = mm_camera_util_get_channel_by_handler(my_obj, ch_id);
--->mm_channel_qbuf(ch_obj, buf);
--->mm_stream_t* s_obj = mm_channel_util_get_stream_by_handler(my_obj, buf->stream_id); //後面的 my_obj 是這裡得到的
--->mm_stream_fsm_fn(s_obj, MM_STREAM_EVT_QBUF, (void *)buf, NULL);
--->mm_stream_fsm_active(my_obj, evt, in_val, out_val);
--->mm_stream_buf_done(my_obj, (mm_camera_buf_def_t *)in_val);
--->mm_stream_qbuf(my_obj, frame);
--->struct v4l2_buffer buffer;
--->buffer.type = V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE;
--->buffer.memory = V4L2_MEMORY_USERPTR;
--->buffer.index = (__u32)buf->buf_idx;
--->buffer.length = (__u32)length;
--->ioctl(my_obj->fd, VIDIOC_QBUF, &buffer); //最終調用到ioctl(VIDIOC_QBUF)
--->m_camOps->start_channel(m_camHandle, m_handle); //m_camOps = mm_camera_ops 就是調用 mm_camera_intf_start_channel()
--->uint32_t handle = get_main_camera_handle(camera_handle);
--->my_obj = mm_camera_util_get_camera_by_handler(handle);
--->mm_camera_start_channel(my_obj, chid);
--->mm_channel_t * ch_obj = mm_camera_util_get_channel_by_handler(my_obj, ch_id);
--->mm_channel_fsm_fn(ch_obj, MM_CHANNEL_EVT_START, NULL, NULL);
--->mm_channel_fsm_fn_stopped(my_obj, evt, in_val, out_val); //因為還沒啟動，是以狀态是 MM_CHANNEL_STATE_STOPPED
--->mm_channel_start(my_obj);
--->mm_stream_fsm_fn(s_objs[i], MM_STREAM_EVT_GET_BUF, NULL, NULL); //配置設定buf, 這裡隻是設定buf的大小等資訊
--->mm_stream_init_bufs(my_obj);
--->mm_stream_fsm_fn(s_objs[i], MM_STREAM_EVT_REG_BUF, NULL, NULL); //注冊buf
--->mm_stream_fsm_buffed(my_obj, evt, in_val, out_val);
--->mm_stream_reg_buf(my_obj);
--->mm_stream_request_buf(my_obj);
--->struct v4l2_requestbuffers bufreq;
--->bufreq.count = buf_num;
--->bufreq.type = V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE;
--->bufreq.memory = V4L2_MEMORY_USERPTR;
--->ioctl(my_obj->fd, VIDIOC_REQBUFS, &bufreq); //調用 ioctl(VIDIOC_REQBUFS) 在核心空間配置設定記憶體， 之後用mmap映射出來
--->mm_stream_qbuf(my_obj, &my_obj->buf[i]); //第一次的時候參考 《VIDIOC_DQBUF 分析》
--->buffer.type = V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE;
--->buffer.memory = V4L2_MEMORY_USERPTR;
--->buffer.index = (__u32)buf->buf_idx;
--->ioctl(my_obj->fd, VIDIOC_QBUF, &buffer); //調用 ioctl(VIDIOC_QBUF) 将 buf 挂入驅動隊列
--->mm_stream_fsm_fn(s_objs[i], MM_STREAM_EVT_START, NULL, NULL); //啟動
--->mm_stream_fsm_reg(my_obj, evt, in_val, out_val);
--->my_obj->state = MM_STREAM_STATE_ACTIVE;
--->mm_camera_cmd_thread_launch(&my_obj->cmd_thread, mm_stream_dispatch_app_data, (void *)my_obj); //開啟線程
--->my_obj->buf_cb[i].cb(&super_buf, my_obj->buf_cb[i].user_data); //就是調用 dataNotifyCB
--->QCameraStream* stream = (QCameraStream *)userdata;
--->mm_camera_super_buf_t *frame = (mm_camera_super_buf_t *)malloc(sizeof(mm_camera_super_buf_t));
--->*frame = *recvd_frame;
--->stream->processDataNotify(frame);
--->mDataQ.enqueue((void *)frame)
--->mProcTh.sendCmd(CAMERA_CMD_TYPE_DO_NEXT_JOB, FALSE, FALSE); //喚醒 dataProcRoutine 線程
--->mm_stream_streamon(my_obj);
--->enum v4l2_buf_type buf_type = V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE;
--->ioctl(my_obj->fd, VIDIOC_STREAMON, &buf_type); //調用 ioctl(VIDIOC_STREAMON) 啟動傳輸
m_stateMachine 狀态機分析
QCamera2HardwareInterface *hw = new QCamera2HardwareInterface((uint32_t)camera_id);
--->m_stateMachine(this) //m_stateMachine = QCamera2HardwareInterface
--->api_queue()
--->evt_queue()
--->m_parent = ctrl; //ctrl = QCamera2HardwareInterface 對象
--->cam_sem_init(&cmd_sem, 0);
--->pthread_create(&cmd_pid, NULL, smEvtProcRoutine, this); // this = QCameraStateMachine 對象
--->QCameraStateMachine *pme = (QCameraStateMachine *)data;
--->cam_sem_wait(&pme->cmd_sem);
--->qcamera_sm_cmd_t *node = (qcamera_sm_cmd_t *)pme->api_queue.dequeue(); //從隊裡中取出資料
--->do {
--->pme->stateMachine(node->evt, node->evt_payload); //最終會調用這個函數
--->}while (1)
--->
VIDIOC_DQBUF 分析
mm_stream_qbuf() //向kernel層配置設定完buf之後需要循環調用 VIDIOC_QBUF 将buf挂入驅動的連結清單上，這裡是第一次執行的情況
--->mm_camera_poll_thread_add_poll_fd(&my_obj->ch_obj->poll_thread[0], idx, my_obj->my_hdl, my_obj->fd, mm_stream_data_notify, (void*)my_obj, mm_camera_async_call); //将 my_obj->fd 注冊進 poll
--->poll_cb->poll_entries[idx].fd = fd;
--->poll_cb->poll_entries[idx].handler = handler;
--->poll_cb->poll_entries[idx].notify_cb = notify_cb;
--->poll_cb->poll_entries[idx].user_data = userdata;
--->mm_camera_poll_sig_async(poll_cb, MM_CAMERA_PIPE_CMD_POLL_ENTRIES_UPDATED_ASYNC );
--->write(poll_cb->pfds[1], &cmd_evt, sizeof(cmd_evt));
調用 notify_cb 回調函數
mm_stream_data_notify(void* user_data) //當驅動有資料時調用這個回調 注意：有一個線程專門調用回調
--->mm_stream_t *my_obj = (mm_stream_t*)user_data;
--->mm_stream_read_msm_frame(my_obj, &buf_info, (uint8_t)length); //讀取一幀的資料
--->struct v4l2_buffer vb;
--->vb.type = V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE;
--->vb.memory = V4L2_MEMORY_USERPTR;
--->vb.length = num_planes;
--->ioctl(my_obj->fd, VIDIOC_DQBUF, &vb); //調用 VIDIOC_DQBUF 從驅動隊列上取出buf
--->buf_info->buf = &my_obj->buf[idx];
--->buf_info->frame_idx = vb.sequence;
--->buf_info->buf->buf_idx = idx;
--->buf_info->buf->frame_idx = vb.sequence;
--->mm_stream_handle_rcvd_buf(my_obj, &buf_info, has_cb);
--->node = (mm_camera_cmdcb_t *)malloc(sizeof(mm_camera_cmdcb_t));
--->node->cmd_type = MM_CAMERA_CMD_TYPE_DATA_CB;
--->node->u.buf = *buf_info;
--->cam_queue_enq(&(my_obj->cmd_thread.cmd_queue), node); //插入隊列
--->cam_sem_post(&(my_obj->cmd_thread.cmd_sem)); //喚醒 mm_stream_dispatch_app_data 線程
總結
這些流程的代碼量實在是太巨大了，是以就沒有貼代碼上來。而是貼筆記，筆記裡面已經寫得非常完善了。
其實對比API1和API2，很明顯的發現API1的代碼簡單很多，流程也更加清晰
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