Merge "Camera3Device: Support batch requests" into mnc-dr-dev

8 files changed, 387 insertions, 199 deletions

diff --git a/services/camera/libcameraservice/device3/Camera3Device.cpp b/services/camera/libcameraservice/device3/Camera3Device.cpp
index ec3591f..98d0a41 100644
--- a/services/camera/libcameraservice/device3/Camera3Device.cpp
+++ b/services/camera/libcameraservice/device3/Camera3Device.cpp
@@ -565,6 +565,18 @@ status_t Camera3Device::convertMetadataListToRequestListLocked(
 
         ALOGV("%s: requestId = %" PRId32, __FUNCTION__, newRequest->mResultExtras.requestId);
     }
+
+    // Setup batch size if this is a high speed video recording request.
+    if (mIsConstrainedHighSpeedConfiguration && requestList->size() > 0) {
+        auto firstRequest = requestList->begin();
+        for (auto& outputStream : (*firstRequest)->mOutputStreams) {
+            if (outputStream->isVideoStream()) {
+                (*firstRequest)->mBatchSize = requestList->size();
+                break;
+            }
+        }
+    }
+
     return OK;
 }
 
@@ -1406,7 +1418,7 @@ status_t Camera3Device::flush(int64_t *frameNumber) {
 
     status_t res;
     if (mHal3Device->common.version >= CAMERA_DEVICE_API_VERSION_3_1) {
-        res = mHal3Device->ops->flush(mHal3Device);
+        res = mRequestThread->flush();
     } else {
         Mutex::Autolock l(mLock);
         res = waitUntilDrainedLocked();
@@ -1595,6 +1607,7 @@ sp<Camera3Device::CaptureRequest> Camera3Device::createCaptureRequest(
         newRequest->mOutputStreams.push(stream);
     }
     newRequest->mSettings.erase(ANDROID_REQUEST_OUTPUT_STREAMS);
+    newRequest->mBatchSize = 1;
 
     return newRequest;
 }
@@ -2766,6 +2779,17 @@ status_t Camera3Device::RequestThread::clear(
     return OK;
 }
 
+status_t Camera3Device::RequestThread::flush() {
+    ATRACE_CALL();
+    Mutex::Autolock l(mFlushLock);
+
+    if (mHal3Device->common.version >= CAMERA_DEVICE_API_VERSION_3_1) {
+        return mHal3Device->ops->flush(mHal3Device);
+    }
+
+    return -ENOTSUP;
+}
+
 void Camera3Device::RequestThread::setPaused(bool paused) {
     Mutex::Autolock l(mPauseLock);
     mDoPause = paused;
@@ -2856,7 +2880,7 @@ void Camera3Device::overrideResultForPrecaptureCancel(
 }
 
 bool Camera3Device::RequestThread::threadLoop() {
-
+    ATRACE_CALL();
     status_t res;
 
     // Handle paused state.
@@ -2864,203 +2888,246 @@ bool Camera3Device::RequestThread::threadLoop() {
         return true;
     }
 
-    // Get work to do
-
-    sp<CaptureRequest> nextRequest = waitForNextRequest();
-    if (nextRequest == NULL) {
+    // Get next batch of requests.
+    Vector<NextRequest> nextRequests;
+    waitForNextRequestBatch(&nextRequests);
+    const size_t numRequests = nextRequests.size();
+    if (numRequests == 0) {
         return true;
     }
 
-    // Create request to HAL
-    camera3_capture_request_t request = camera3_capture_request_t();
-    request.frame_number = nextRequest->mResultExtras.frameNumber;
-    Vector<camera3_stream_buffer_t> outputBuffers;
-
-    // Get the request ID, if any
-    int requestId;
-    camera_metadata_entry_t requestIdEntry =
-            nextRequest->mSettings.find(ANDROID_REQUEST_ID);
+    // Get the latest request ID, if any
+    int latestRequestId;
+    camera_metadata_entry_t requestIdEntry = nextRequests[nextRequests.size() - 1].
+            captureRequest->mSettings.find(ANDROID_REQUEST_ID);
     if (requestIdEntry.count > 0) {
-        requestId = requestIdEntry.data.i32[0];
+        latestRequestId = requestIdEntry.data.i32[0];
     } else {
-        ALOGW("%s: Did not have android.request.id set in the request",
-                __FUNCTION__);
-        requestId = NAME_NOT_FOUND;
+        ALOGW("%s: Did not have android.request.id set in the request.", __FUNCTION__);
+        latestRequestId = NAME_NOT_FOUND;
     }
 
-    // Insert any queued triggers (before metadata is locked)
-    int32_t triggerCount;
-    res = insertTriggers(nextRequest);
-    if (res < 0) {
-        SET_ERR("RequestThread: Unable to insert triggers "
-                "(capture request %d, HAL device: %s (%d)",
-                request.frame_number, strerror(-res), res);
-        cleanUpFailedRequest(request, nextRequest, outputBuffers);
+    // Prepare a batch of HAL requests and output buffers.
+    res = prepareHalRequests(&nextRequests);
+    if (res == TIMED_OUT) {
+        // Not a fatal error if getting output buffers time out.
+        cleanUpFailedRequests(&nextRequests, /*sendRequestError*/ true);
+        return true;
+    } else if (res != OK) {
+        cleanUpFailedRequests(&nextRequests, /*sendRequestError*/ false);
         return false;
     }
-    triggerCount = res;
 
-    bool triggersMixedIn = (triggerCount > 0 || mPrevTriggers > 0);
+    // Inform waitUntilRequestProcessed thread of a new request ID
+    {
+        Mutex::Autolock al(mLatestRequestMutex);
+
+        mLatestRequestId = latestRequestId;
+        mLatestRequestSignal.signal();
+    }
+
+    // Submit a batch of requests to HAL.
+    // Use flush lock only when submitting multilple requests in a batch.
+    // TODO: The problem with flush lock is flush() will be blocked by process_capture_request()
+    // which may take a long time to finish so synchronizing flush() and
+    // process_capture_request() defeats the purpose of cancelling requests ASAP with flush().
+    // For now, only synchronize for high speed recording and we should figure something out for
+    // removing the synchronization.
+    bool useFlushLock = nextRequests.size() > 1;
+
+    if (useFlushLock) {
+        mFlushLock.lock();
+    }
+
+    ALOGVV("%s: %d: submitting %d requests in a batch.", __FUNCTION__, __LINE__,
+            nextRequests.size());
+    for (auto& nextRequest : nextRequests) {
+        // Submit request and block until ready for next one
+        ATRACE_ASYNC_BEGIN("frame capture", nextRequest.halRequest.frame_number);
+        ATRACE_BEGIN("camera3->process_capture_request");
+        res = mHal3Device->ops->process_capture_request(mHal3Device, &nextRequest.halRequest);
+        ATRACE_END();
 
-    // If the request is the same as last, or we had triggers last time
-    if (mPrevRequest != nextRequest || triggersMixedIn) {
-        /**
-         * HAL workaround:
-         * Insert a dummy trigger ID if a trigger is set but no trigger ID is
-         */
-        res = addDummyTriggerIds(nextRequest);
         if (res != OK) {
-            SET_ERR("RequestThread: Unable to insert dummy trigger IDs "
-                    "(capture request %d, HAL device: %s (%d)",
-                    request.frame_number, strerror(-res), res);
-            cleanUpFailedRequest(request, nextRequest, outputBuffers);
+            // Should only get a failure here for malformed requests or device-level
+            // errors, so consider all errors fatal.  Bad metadata failures should
+            // come through notify.
+            SET_ERR("RequestThread: Unable to submit capture request %d to HAL"
+                    " device: %s (%d)", nextRequest.halRequest.frame_number, strerror(-res),
+                    res);
+            cleanUpFailedRequests(&nextRequests, /*sendRequestError*/ false);
+            if (useFlushLock) {
+                mFlushLock.unlock();
+            }
             return false;
         }
 
-        /**
-         * The request should be presorted so accesses in HAL
-         *   are O(logn). Sidenote, sorting a sorted metadata is nop.
-         */
-        nextRequest->mSettings.sort();
-        request.settings = nextRequest->mSettings.getAndLock();
-        mPrevRequest = nextRequest;
-        ALOGVV("%s: Request settings are NEW", __FUNCTION__);
-
-        IF_ALOGV() {
-            camera_metadata_ro_entry_t e = camera_metadata_ro_entry_t();
-            find_camera_metadata_ro_entry(
-                    request.settings,
-                    ANDROID_CONTROL_AF_TRIGGER,
-                    &e
-            );
-            if (e.count > 0) {
-                ALOGV("%s: Request (frame num %d) had AF trigger 0x%x",
-                      __FUNCTION__,
-                      request.frame_number,
-                      e.data.u8[0]);
-            }
-        }
-    } else {
-        // leave request.settings NULL to indicate 'reuse latest given'
-        ALOGVV("%s: Request settings are REUSED",
-               __FUNCTION__);
-    }
+        // Mark that the request has be submitted successfully.
+        nextRequest.submitted = true;
 
-    uint32_t totalNumBuffers = 0;
+        // Update the latest request sent to HAL
+        if (nextRequest.halRequest.settings != NULL) { // Don't update if they were unchanged
+            Mutex::Autolock al(mLatestRequestMutex);
 
-    // Fill in buffers
-    if (nextRequest->mInputStream != NULL) {
-        request.input_buffer = &nextRequest->mInputBuffer;
-        totalNumBuffers += 1;
-    } else {
-        request.input_buffer = NULL;
-    }
+            camera_metadata_t* cloned = clone_camera_metadata(nextRequest.halRequest.settings);
+            mLatestRequest.acquire(cloned);
+        }
+
+        if (nextRequest.halRequest.settings != NULL) {
+            nextRequest.captureRequest->mSettings.unlock(nextRequest.halRequest.settings);
+        }
 
-    outputBuffers.insertAt(camera3_stream_buffer_t(), 0,
-            nextRequest->mOutputStreams.size());
-    request.output_buffers = outputBuffers.array();
-    for (size_t i = 0; i < nextRequest->mOutputStreams.size(); i++) {
-        res = nextRequest->mOutputStreams.editItemAt(i)->
-                getBuffer(&outputBuffers.editItemAt(i));
+        // Remove any previously queued triggers (after unlock)
+        res = removeTriggers(mPrevRequest);
         if (res != OK) {
-            // Can't get output buffer from gralloc queue - this could be due to
-            // abandoned queue or other consumer misbehavior, so not a fatal
-            // error
-            ALOGE("RequestThread: Can't get output buffer, skipping request:"
-                    " %s (%d)", strerror(-res), res);
-            {
-                Mutex::Autolock l(mRequestLock);
-                if (mListener != NULL) {
-                    mListener->notifyError(
-                            ICameraDeviceCallbacks::ERROR_CAMERA_REQUEST,
-                            nextRequest->mResultExtras);
-                }
+            SET_ERR("RequestThread: Unable to remove triggers "
+                  "(capture request %d, HAL device: %s (%d)",
+                  nextRequest.halRequest.frame_number, strerror(-res), res);
+            cleanUpFailedRequests(&nextRequests, /*sendRequestError*/ false);
+            if (useFlushLock) {
+                mFlushLock.unlock();
             }
-            cleanUpFailedRequest(request, nextRequest, outputBuffers);
-            return true;
+            return false;
         }
-        request.num_output_buffers++;
     }
-    totalNumBuffers += request.num_output_buffers;
 
-    // Log request in the in-flight queue
-    sp<Camera3Device> parent = mParent.promote();
-    if (parent == NULL) {
-        // Should not happen, and nowhere to send errors to, so just log it
-        CLOGE("RequestThread: Parent is gone");
-        cleanUpFailedRequest(request, nextRequest, outputBuffers);
-        return false;
+    if (useFlushLock) {
+        mFlushLock.unlock();
     }
 
-    res = parent->registerInFlight(request.frame_number,
-            totalNumBuffers, nextRequest->mResultExtras,
-            /*hasInput*/request.input_buffer != NULL,
-            nextRequest->mAeTriggerCancelOverride);
-    ALOGVV("%s: registered in flight requestId = %" PRId32 ", frameNumber = %" PRId64
-           ", burstId = %" PRId32 ".",
-            __FUNCTION__,
-            nextRequest->mResultExtras.requestId, nextRequest->mResultExtras.frameNumber,
-            nextRequest->mResultExtras.burstId);
-    if (res != OK) {
-        SET_ERR("RequestThread: Unable to register new in-flight request:"
-                " %s (%d)", strerror(-res), res);
-        cleanUpFailedRequest(request, nextRequest, outputBuffers);
-        return false;
+    // Unset as current request
+    {
+        Mutex::Autolock l(mRequestLock);
+        mNextRequests.clear();
     }
 
-    // Inform waitUntilRequestProcessed thread of a new request ID
-    {
-        Mutex::Autolock al(mLatestRequestMutex);
+    return true;
+}
 
-        mLatestRequestId = requestId;
-        mLatestRequestSignal.signal();
+status_t Camera3Device::RequestThread::prepareHalRequests(Vector<NextRequest> *nextRequests) {
+    ATRACE_CALL();
+
+    if (nextRequests == nullptr) {
+        return BAD_VALUE;
     }
 
-    // Submit request and block until ready for next one
-    ATRACE_ASYNC_BEGIN("frame capture", request.frame_number);
-    ATRACE_BEGIN("camera3->process_capture_request");
-    res = mHal3Device->ops->process_capture_request(mHal3Device, &request);
-    ATRACE_END();
+    for (auto& nextRequest : *nextRequests) {
+        sp<CaptureRequest> captureRequest = nextRequest.captureRequest;
+        camera3_capture_request_t* halRequest = &nextRequest.halRequest;
+        Vector<camera3_stream_buffer_t>* outputBuffers = &nextRequest.outputBuffers;
 
-    if (res != OK) {
-        // Should only get a failure here for malformed requests or device-level
-        // errors, so consider all errors fatal.  Bad metadata failures should
-        // come through notify.
-        SET_ERR("RequestThread: Unable to submit capture request %d to HAL"
-                " device: %s (%d)", request.frame_number, strerror(-res), res);
-        cleanUpFailedRequest(request, nextRequest, outputBuffers);
-        return false;
-    }
+        // Prepare a request to HAL
+        halRequest->frame_number = captureRequest->mResultExtras.frameNumber;
 
-    // Update the latest request sent to HAL
-    if (request.settings != NULL) { // Don't update them if they were unchanged
-        Mutex::Autolock al(mLatestRequestMutex);
+        // Insert any queued triggers (before metadata is locked)
+        status_t res = insertTriggers(captureRequest);
 
-        camera_metadata_t* cloned = clone_camera_metadata(request.settings);
-        mLatestRequest.acquire(cloned);
-    }
+        if (res < 0) {
+            SET_ERR("RequestThread: Unable to insert triggers "
+                    "(capture request %d, HAL device: %s (%d)",
+                    halRequest->frame_number, strerror(-res), res);
+            return INVALID_OPERATION;
+        }
+        int triggerCount = res;
+        bool triggersMixedIn = (triggerCount > 0 || mPrevTriggers > 0);
+        mPrevTriggers = triggerCount;
 
-    if (request.settings != NULL) {
-        nextRequest->mSettings.unlock(request.settings);
-    }
+        // If the request is the same as last, or we had triggers last time
+        if (mPrevRequest != captureRequest || triggersMixedIn) {
+            /**
+             * HAL workaround:
+             * Insert a dummy trigger ID if a trigger is set but no trigger ID is
+             */
+            res = addDummyTriggerIds(captureRequest);
+            if (res != OK) {
+                SET_ERR("RequestThread: Unable to insert dummy trigger IDs "
+                        "(capture request %d, HAL device: %s (%d)",
+                        halRequest->frame_number, strerror(-res), res);
+                return INVALID_OPERATION;
+            }
 
-    // Unset as current request
-    {
-        Mutex::Autolock l(mRequestLock);
-        mNextRequest.clear();
-    }
+            /**
+             * The request should be presorted so accesses in HAL
+             *   are O(logn). Sidenote, sorting a sorted metadata is nop.
+             */
+            captureRequest->mSettings.sort();
+            halRequest->settings = captureRequest->mSettings.getAndLock();
+            mPrevRequest = captureRequest;
+            ALOGVV("%s: Request settings are NEW", __FUNCTION__);
+
+            IF_ALOGV() {
+                camera_metadata_ro_entry_t e = camera_metadata_ro_entry_t();
+                find_camera_metadata_ro_entry(
+                        halRequest->settings,
+                        ANDROID_CONTROL_AF_TRIGGER,
+                        &e
+                );
+                if (e.count > 0) {
+                    ALOGV("%s: Request (frame num %d) had AF trigger 0x%x",
+                          __FUNCTION__,
+                          halRequest->frame_number,
+                          e.data.u8[0]);
+                }
+            }
+        } else {
+            // leave request.settings NULL to indicate 'reuse latest given'
+            ALOGVV("%s: Request settings are REUSED",
+                   __FUNCTION__);
+        }
 
-    // Remove any previously queued triggers (after unlock)
-    res = removeTriggers(mPrevRequest);
-    if (res != OK) {
-        SET_ERR("RequestThread: Unable to remove triggers "
-              "(capture request %d, HAL device: %s (%d)",
-              request.frame_number, strerror(-res), res);
-        return false;
+        uint32_t totalNumBuffers = 0;
+
+        // Fill in buffers
+        if (captureRequest->mInputStream != NULL) {
+            halRequest->input_buffer = &captureRequest->mInputBuffer;
+            totalNumBuffers += 1;
+        } else {
+            halRequest->input_buffer = NULL;
+        }
+
+        outputBuffers->insertAt(camera3_stream_buffer_t(), 0,
+                captureRequest->mOutputStreams.size());
+        halRequest->output_buffers = outputBuffers->array();
+        for (size_t i = 0; i < captureRequest->mOutputStreams.size(); i++) {
+            res = captureRequest->mOutputStreams.editItemAt(i)->
+                    getBuffer(&outputBuffers->editItemAt(i));
+            if (res != OK) {
+                // Can't get output buffer from gralloc queue - this could be due to
+                // abandoned queue or other consumer misbehavior, so not a fatal
+                // error
+                ALOGE("RequestThread: Can't get output buffer, skipping request:"
+                        " %s (%d)", strerror(-res), res);
+
+                return TIMED_OUT;
+            }
+            halRequest->num_output_buffers++;
+        }
+        totalNumBuffers += halRequest->num_output_buffers;
+
+        // Log request in the in-flight queue
+        sp<Camera3Device> parent = mParent.promote();
+        if (parent == NULL) {
+            // Should not happen, and nowhere to send errors to, so just log it
+            CLOGE("RequestThread: Parent is gone");
+            return INVALID_OPERATION;
+        }
+        res = parent->registerInFlight(halRequest->frame_number,
+                totalNumBuffers, captureRequest->mResultExtras,
+                /*hasInput*/halRequest->input_buffer != NULL,
+                captureRequest->mAeTriggerCancelOverride);
+        ALOGVV("%s: registered in flight requestId = %" PRId32 ", frameNumber = %" PRId64
+               ", burstId = %" PRId32 ".",
+                __FUNCTION__,
+                captureRequest->mResultExtras.requestId, captureRequest->mResultExtras.frameNumber,
+                captureRequest->mResultExtras.burstId);
+        if (res != OK) {
+            SET_ERR("RequestThread: Unable to register new in-flight request:"
+                    " %s (%d)", strerror(-res), res);
+            return INVALID_OPERATION;
+        }
     }
-    mPrevTriggers = triggerCount;
 
-    return true;
+    return OK;
 }
 
 CameraMetadata Camera3Device::RequestThread::getLatestRequest() const {
@@ -3075,11 +3142,11 @@ bool Camera3Device::RequestThread::isStreamPending(
         sp<Camera3StreamInterface>& stream) {
     Mutex::Autolock l(mRequestLock);
 
-    if (mNextRequest != nullptr) {
-        for (const auto& s : mNextRequest->mOutputStreams) {
+    for (const auto& nextRequest : mNextRequests) {
+        for (const auto& s : nextRequest->mOutputStreams) {
             if (stream == s) return true;
         }
-        if (stream == mNextRequest->mInputStream) return true;
+        if (stream == nextRequest->mInputStream) return true;
     }
 
     for (const auto& request : mRequestQueue) {
@@ -3099,37 +3166,104 @@ bool Camera3Device::RequestThread::isStreamPending(
     return false;
 }
 
-void Camera3Device::RequestThread::cleanUpFailedRequest(
-        camera3_capture_request_t &request,
-        sp<CaptureRequest> &nextRequest,
-        Vector<camera3_stream_buffer_t> &outputBuffers) {
-
-    if (request.settings != NULL) {
-        nextRequest->mSettings.unlock(request.settings);
-    }
-    if (nextRequest->mInputStream != NULL) {
-        nextRequest->mInputBuffer.status = CAMERA3_BUFFER_STATUS_ERROR;
-        nextRequest->mInputStream->returnInputBuffer(nextRequest->mInputBuffer);
+void Camera3Device::RequestThread::cleanUpFailedRequests(Vector<NextRequest> *nextRequests,
+        bool sendRequestError) {
+    if (nextRequests == nullptr) {
+        return;
     }
-    for (size_t i = 0; i < request.num_output_buffers; i++) {
-        outputBuffers.editItemAt(i).status = CAMERA3_BUFFER_STATUS_ERROR;
-        nextRequest->mOutputStreams.editItemAt(i)->returnBuffer(
-            outputBuffers[i], 0);
+
+    for (auto& nextRequest : *nextRequests) {
+        // Skip the ones that have been submitted successfully.
+        if (nextRequest.submitted) {
+            continue;
+        }
+
+        sp<CaptureRequest> captureRequest = nextRequest.captureRequest;
+        camera3_capture_request_t* halRequest = &nextRequest.halRequest;
+        Vector<camera3_stream_buffer_t>* outputBuffers = &nextRequest.outputBuffers;
+
+        if (halRequest->settings != NULL) {
+            captureRequest->mSettings.unlock(halRequest->settings);
+        }
+
+        if (captureRequest->mInputStream != NULL) {
+            captureRequest->mInputBuffer.status = CAMERA3_BUFFER_STATUS_ERROR;
+            captureRequest->mInputStream->returnInputBuffer(captureRequest->mInputBuffer);
+        }
+
+        for (size_t i = 0; i < halRequest->num_output_buffers; i++) {
+            outputBuffers->editItemAt(i).status = CAMERA3_BUFFER_STATUS_ERROR;
+            captureRequest->mOutputStreams.editItemAt(i)->returnBuffer((*outputBuffers)[i], 0);
+        }
+
+        if (sendRequestError) {
+            Mutex::Autolock l(mRequestLock);
+            if (mListener != NULL) {
+                mListener->notifyError(
+                        ICameraDeviceCallbacks::ERROR_CAMERA_REQUEST,
+                        captureRequest->mResultExtras);
+            }
+        }
     }
 
     Mutex::Autolock l(mRequestLock);
-    mNextRequest.clear();
+    mNextRequests.clear();
+    nextRequests->clear();
 }
 
-sp<Camera3Device::CaptureRequest>
-        Camera3Device::RequestThread::waitForNextRequest() {
-    status_t res;
-    sp<CaptureRequest> nextRequest;
+void Camera3Device::RequestThread::waitForNextRequestBatch(Vector<NextRequest> *nextRequests) {
+    if (nextRequests == nullptr) {
+        return;
+    }
 
     // Optimized a bit for the simple steady-state case (single repeating
     // request), to avoid putting that request in the queue temporarily.
     Mutex::Autolock l(mRequestLock);
 
+    nextRequests->clear();
+    assert(mNextRequests.empty());
+
+    NextRequest nextRequest;
+    nextRequest.captureRequest = waitForNextRequestLocked();
+    if (nextRequest.captureRequest == nullptr) {
+        return;
+    }
+
+    nextRequest.halRequest = camera3_capture_request_t();
+    nextRequest.submitted = false;
+    nextRequests->add(nextRequest);
+    mNextRequests.push_back(nextRequest.captureRequest);
+
+    // Wait for additional requests
+    const size_t batchSize = nextRequest.captureRequest->mBatchSize;
+
+    for (size_t i = 1; i < batchSize; i++) {
+        NextRequest additionalRequest;
+        additionalRequest.captureRequest = waitForNextRequestLocked();
+        if (additionalRequest.captureRequest == nullptr) {
+            break;
+        }
+
+        additionalRequest.halRequest = camera3_capture_request_t();
+        additionalRequest.submitted = false;
+        nextRequests->add(additionalRequest);
+        mNextRequests.push_back(additionalRequest.captureRequest);
+    }
+
+    if (nextRequests->size() < batchSize) {
+        ALOGE("RequestThread: only get %d out of %d requests. Skipping requests.",
+                nextRequests->size(), batchSize);
+        cleanUpFailedRequests(nextRequests, /*sendRequestError*/true);
+    }
+
+    return;
+}
+
+sp<Camera3Device::CaptureRequest>
+        Camera3Device::RequestThread::waitForNextRequestLocked() {
+    status_t res;
+    sp<CaptureRequest> nextRequest;
+
     while (mRequestQueue.empty()) {
         if (!mRepeatingRequests.empty()) {
             // Always atomically enqueue all requests in a repeating request
@@ -3224,8 +3358,6 @@ sp<Camera3Device::CaptureRequest>
 
     handleAePrecaptureCancelRequest(nextRequest);
 
-    mNextRequest = nextRequest;
-
     return nextRequest;
 }
 
diff --git a/services/camera/libcameraservice/device3/Camera3Device.h b/services/camera/libcameraservice/device3/Camera3Device.h
index 1f39940..a3abbaf 100644
--- a/services/camera/libcameraservice/device3/Camera3Device.h
+++ b/services/camera/libcameraservice/device3/Camera3Device.h
@@ -264,6 +264,11 @@ class Camera3Device :
         // Used to cancel AE precapture trigger for devices doesn't support
         // CONTROL_AE_PRECAPTURE_TRIGGER_CANCEL
         AeTriggerCancelOverride_t           mAeTriggerCancelOverride;
+        // The number of requests that should be submitted to HAL at a time.
+        // For example, if batch size is 8, this request and the following 7
+        // requests will be submitted to HAL at a time. The batch size for
+        // the following 7 requests will be ignored by the request thread.
+        int                                 mBatchSize;
     };
     typedef List<sp<CaptureRequest> > RequestList;
 
@@ -441,6 +446,11 @@ class Camera3Device :
                        int64_t *lastFrameNumber = NULL);
 
         /**
+         * Flush all pending requests in HAL.
+         */
+        status_t flush();
+
+        /**
          * Queue a trigger to be dispatched with the next outgoing
          * process_capture_request. The settings for that request only
          * will be temporarily rewritten to add the trigger tag/value.
@@ -501,16 +511,28 @@ class Camera3Device :
 
         static const nsecs_t kRequestTimeout = 50e6; // 50 ms
 
-        // Waits for a request, or returns NULL if times out.
-        sp<CaptureRequest> waitForNextRequest();
+        // Used to prepare a batch of requests.
+        struct NextRequest {
+            sp<CaptureRequest>              captureRequest;
+            camera3_capture_request_t       halRequest;
+            Vector<camera3_stream_buffer_t> outputBuffers;
+            bool                            submitted;
+        };
+
+        // Wait for the next batch of requests.
+        void waitForNextRequestBatch(Vector<NextRequest> *nextRequests);
 
-        // Return buffers, etc, for a request that couldn't be fully
-        // constructed. The buffers will be returned in the ERROR state
-        // to mark them as not having valid data.
-        // All arguments will be modified.
-        void cleanUpFailedRequest(camera3_capture_request_t &request,
-                sp<CaptureRequest> &nextRequest,
-                Vector<camera3_stream_buffer_t> &outputBuffers);
+        // Waits for a request, or returns NULL if times out. Must be called with mRequestLock hold.
+        sp<CaptureRequest> waitForNextRequestLocked();
+
+        // Prepare a HAL request and output buffers. Return TIMED_OUT if getting any output buffer
+        // timed out. If an error is returned, the caller should clean up the pending request batch.
+        status_t prepareHalRequests(Vector<NextRequest> *nextRequests);
+
+        // Return buffers, etc, for a request that couldn't be fully constructed and send request
+        // errors if sendRequestError is true. The buffers will be returned in the ERROR state
+        // to mark them as not having valid data. nextRequests will be modified.
+        void cleanUpFailedRequests(Vector<NextRequest> *nextRequests, bool sendRequestError);
 
         // Pause handling
         bool               waitIfPaused();
@@ -539,10 +561,13 @@ class Camera3Device :
         Condition          mRequestSignal;
         RequestList        mRequestQueue;
         RequestList        mRepeatingRequests;
-        // The next request being prepped for submission to the HAL, no longer
+        // The next requests being prepped for submission to the HAL, no longer
         // on the request queue. Read-only even with mRequestLock held, outside
         // of threadLoop
-        sp<const CaptureRequest> mNextRequest;
+        RequestList        mNextRequests;
+
+        // To protect flush() and sending a request batch to HAL.
+        Mutex              mFlushLock;
 
         bool               mReconfigured;
 
diff --git a/services/camera/libcameraservice/device3/Camera3DummyStream.cpp b/services/camera/libcameraservice/device3/Camera3DummyStream.cpp
index ecb8ac8..1d9d04f 100644
--- a/services/camera/libcameraservice/device3/Camera3DummyStream.cpp
+++ b/services/camera/libcameraservice/device3/Camera3DummyStream.cpp
@@ -92,6 +92,10 @@ status_t Camera3DummyStream::getEndpointUsage(uint32_t *usage) const {
     return OK;
 }
 
+bool Camera3DummyStream::isVideoStream() const {
+    return false;
+}
+
 }; // namespace camera3
 
 }; // namespace android
diff --git a/services/camera/libcameraservice/device3/Camera3DummyStream.h b/services/camera/libcameraservice/device3/Camera3DummyStream.h
index 3a3dbf4..97c0c96 100644
--- a/services/camera/libcameraservice/device3/Camera3DummyStream.h
+++ b/services/camera/libcameraservice/device3/Camera3DummyStream.h
@@ -54,6 +54,11 @@ class Camera3DummyStream :
 
     status_t         setTransform(int transform);
 
+    /**
+     * Return if this output stream is for video encoding.
+     */
+    bool isVideoStream() const;
+
   protected:
 
     /**
diff --git a/services/camera/libcameraservice/device3/Camera3OutputStream.cpp b/services/camera/libcameraservice/device3/Camera3OutputStream.cpp
index 8c611d5..3f0a736 100644
--- a/services/camera/libcameraservice/device3/Camera3OutputStream.cpp
+++ b/services/camera/libcameraservice/device3/Camera3OutputStream.cpp
@@ -426,6 +426,17 @@ status_t Camera3OutputStream::getEndpointUsage(uint32_t *usage) const {
     return res;
 }
 
+bool Camera3OutputStream::isVideoStream() const {
+    uint32_t usage = 0;
+    status_t res = getEndpointUsage(&usage);
+    if (res != OK) {
+        ALOGE("%s: getting end point usage failed: %s (%d).", __FUNCTION__, strerror(-res), res);
+        return false;
+    }
+
+    return (usage & GRALLOC_USAGE_HW_VIDEO_ENCODER) != 0;
+}
+
 }; // namespace camera3
 
 }; // namespace android
diff --git a/services/camera/libcameraservice/device3/Camera3OutputStream.h b/services/camera/libcameraservice/device3/Camera3OutputStream.h
index 941d693..3c083ec 100644
--- a/services/camera/libcameraservice/device3/Camera3OutputStream.h
+++ b/services/camera/libcameraservice/device3/Camera3OutputStream.h
@@ -64,6 +64,11 @@ class Camera3OutputStream :
      */
     status_t         setTransform(int transform);
 
+    /**
+     * Return if this output stream is for video encoding.
+     */
+    bool isVideoStream() const;
+
   protected:
     Camera3OutputStream(int id, camera3_stream_type_t type,
             uint32_t width, uint32_t height, int format,
diff --git a/services/camera/libcameraservice/device3/Camera3OutputStreamInterface.h b/services/camera/libcameraservice/device3/Camera3OutputStreamInterface.h
index aae72cf..df89b34 100644
--- a/services/camera/libcameraservice/device3/Camera3OutputStreamInterface.h
+++ b/services/camera/libcameraservice/device3/Camera3OutputStreamInterface.h
@@ -34,6 +34,11 @@ class Camera3OutputStreamInterface : public virtual Camera3StreamInterface {
      * HAL_TRANSFORM_* / NATIVE_WINDOW_TRANSFORM_* constants.
      */
     virtual status_t setTransform(int transform) = 0;
+
+    /**
+     * Return if this output stream is for video encoding.
+     */
+    virtual bool isVideoStream() const = 0;
 };
 
 } // namespace camera3
diff --git a/services/camera/libcameraservice/device3/Camera3Stream.cpp b/services/camera/libcameraservice/device3/Camera3Stream.cpp
index 7163d62..691764f 100644
--- a/services/camera/libcameraservice/device3/Camera3Stream.cpp
+++ b/services/camera/libcameraservice/device3/Camera3Stream.cpp
@@ -455,8 +455,9 @@ status_t Camera3Stream::getBuffer(camera3_stream_buffer *buffer) {
         res = mOutputBufferReturnedSignal.waitRelative(mLock, kWaitForBufferDuration);
         if (res != OK) {
             if (res == TIMED_OUT) {
-                ALOGE("%s: wait for output buffer return timed out after %lldms", __FUNCTION__,
-                        kWaitForBufferDuration / 1000000LL);
+                ALOGE("%s: wait for output buffer return timed out after %lldms (max_buffers %d)",
+                        __FUNCTION__, kWaitForBufferDuration / 1000000LL,
+                        camera3_stream::max_buffers);
             }
             return res;
         }