diff --git a/include/gui/ISensorEventConnection.h b/include/gui/ISensorEventConnection.h
index 00eecc4..f64c6b8 100644
--- a/include/gui/ISensorEventConnection.h
+++ b/include/gui/ISensorEventConnection.h
@@ -39,7 +39,7 @@
     virtual status_t enableDisable(int handle, bool enabled, nsecs_t samplingPeriodNs,
                                    nsecs_t maxBatchReportLatencyNs, int reservedFlags) = 0;
     virtual status_t setEventRate(int handle, nsecs_t ns) = 0;
-    virtual status_t flushSensor(int handle) = 0;
+    virtual status_t flush() = 0;
 };
 
 // ----------------------------------------------------------------------------
diff --git a/include/gui/SensorEventQueue.h b/include/gui/SensorEventQueue.h
index a3a9daa..0bfc7a0 100644
--- a/include/gui/SensorEventQueue.h
+++ b/include/gui/SensorEventQueue.h
@@ -74,7 +74,7 @@
     status_t enableSensor(int32_t handle, int32_t samplingPeriodUs, int maxBatchReportLatencyUs,
                           int reservedFlags) const;
     status_t disableSensor(int32_t handle) const;
-    status_t flushSensor(int32_t handle) const;
+    status_t flush() const;
 
 private:
     sp<Looper> getLooper() const;
diff --git a/libs/gui/ISensorEventConnection.cpp b/libs/gui/ISensorEventConnection.cpp
index a80c661..28fcb53 100644
--- a/libs/gui/ISensorEventConnection.cpp
+++ b/libs/gui/ISensorEventConnection.cpp
@@ -77,10 +77,9 @@
         return reply.readInt32();
     }
 
-    virtual status_t flushSensor(int handle) {
+    virtual status_t flush() {
         Parcel data, reply;
         data.writeInterfaceToken(ISensorEventConnection::getInterfaceDescriptor());
-        data.writeInt32(handle);
         remote()->transact(FLUSH_SENSOR, data, &reply);
         return reply.readInt32();
     }
@@ -122,8 +121,7 @@
         } break;
         case FLUSH_SENSOR: {
             CHECK_INTERFACE(ISensorEventConnection, data, reply);
-            int handle = data.readInt32();
-            status_t result = flushSensor(handle);
+            status_t result = flush();
             reply->writeInt32(result);
             return NO_ERROR;
         } break;
diff --git a/libs/gui/SensorEventQueue.cpp b/libs/gui/SensorEventQueue.cpp
index ab50c1d..c365671 100644
--- a/libs/gui/SensorEventQueue.cpp
+++ b/libs/gui/SensorEventQueue.cpp
@@ -132,8 +132,8 @@
                                                  us2ns(maxBatchReportLatencyUs), reservedFlags);
 }
 
-status_t SensorEventQueue::flushSensor(int32_t handle) const {
-    return mSensorEventConnection->flushSensor(handle);
+status_t SensorEventQueue::flush() const {
+    return mSensorEventConnection->flush();
 }
 
 status_t SensorEventQueue::disableSensor(int32_t handle) const {
diff --git a/services/sensorservice/SensorService.cpp b/services/sensorservice/SensorService.cpp
index b26e572..af605de 100644
--- a/services/sensorservice/SensorService.cpp
+++ b/services/sensorservice/SensorService.cpp
@@ -679,8 +679,12 @@
                                     int handle) {
   if (mInitCheck != NO_ERROR) return mInitCheck;
   SensorInterface* sensor = mSensorMap.valueFor(handle);
-   if (sensor == NULL) {
-       return BAD_VALUE;
+  if (sensor == NULL) {
+      return BAD_VALUE;
+  }
+  if (sensor->getSensor().getType() == SENSOR_TYPE_SIGNIFICANT_MOTION) {
+      ALOGE("flush called on Significant Motion sensor");
+      return INVALID_OPERATION;
   }
   SensorDevice& dev(SensorDevice::getInstance());
 
@@ -934,8 +938,18 @@
     return mService->setEventRate(this, handle, samplingPeriodNs);
 }
 
-status_t  SensorService::SensorEventConnection::flushSensor(int handle) {
-    return mService->flushSensor(this, handle);
+status_t  SensorService::SensorEventConnection::flush() {
+    Mutex::Autolock _l(mConnectionLock);
+    status_t err(NO_ERROR);
+    for (size_t i = 0; i < mSensorInfo.size(); ++i) {
+        const int handle = mSensorInfo.keyAt(i);
+        status_t err_flush = mService->flushSensor(this, handle);
+        if (err_flush != NO_ERROR) {
+            ALOGE("Flush error handle=%d %s", handle, strerror(-err_flush));
+        }
+        err = (err_flush != NO_ERROR) ? err_flush : err;
+    }
+    return err;
 }
 
 // ---------------------------------------------------------------------------
diff --git a/services/sensorservice/SensorService.h b/services/sensorservice/SensorService.h
index 2311bff..2d40071 100644
--- a/services/sensorservice/SensorService.h
+++ b/services/sensorservice/SensorService.h
@@ -79,7 +79,7 @@
         virtual status_t enableDisable(int handle, bool enabled, nsecs_t samplingPeriodNs,
                                        nsecs_t maxBatchReportLatencyNs, int reservedFlags);
         virtual status_t setEventRate(int handle, nsecs_t samplingPeriodNs);
-        virtual status_t flushSensor(int handle);
+        virtual status_t flush();
         // Count the number of flush complete events which are about to be dropped in the buffer.
         // Increment mPendingFlushEventsToSend in mSensorInfo. These flush complete events will be
         // sent separately before the next batch of events.
diff --git a/services/surfaceflinger/DispSync.cpp b/services/surfaceflinger/DispSync.cpp
index 7e67138..b2a604c 100644
--- a/services/surfaceflinger/DispSync.cpp
+++ b/services/surfaceflinger/DispSync.cpp
@@ -397,6 +397,7 @@
     Mutex::Autolock lock(mMutex);
     mPeriod = period;
     mPhase = 0;
+    mThread->updateModel(mPeriod, mPhase);
 }
 
 void DispSync::updateModelLocked() {
diff --git a/services/surfaceflinger/SurfaceFlinger.cpp b/services/surfaceflinger/SurfaceFlinger.cpp
index 3733ede..4a1373e 100644
--- a/services/surfaceflinger/SurfaceFlinger.cpp
+++ b/services/surfaceflinger/SurfaceFlinger.cpp
@@ -2982,6 +2982,27 @@
                         renderScreenImplLocked(hw, reqWidth, reqHeight,
                                 minLayerZ, maxLayerZ, true);
 
+                        // Create a sync point and wait on it, so we know the buffer is
+                        // ready before we pass it along.  We can't trivially call glFlush(),
+                        // so we use a wait flag instead.
+                        // TODO: pass a sync fd to queueBuffer() and let the consumer wait.
+                        EGLSyncKHR sync = eglCreateSyncKHR(mEGLDisplay, EGL_SYNC_FENCE_KHR, NULL);
+                        if (sync != EGL_NO_SYNC_KHR) {
+                            EGLint result = eglClientWaitSyncKHR(mEGLDisplay, sync,
+                                    EGL_SYNC_FLUSH_COMMANDS_BIT_KHR, 2000000000 /*2 sec*/);
+                            EGLint eglErr = eglGetError();
+                            eglDestroySyncKHR(mEGLDisplay, sync);
+                            if (result == EGL_TIMEOUT_EXPIRED_KHR) {
+                                ALOGW("captureScreen: fence wait timed out");
+                            } else {
+                                ALOGW_IF(eglErr != EGL_SUCCESS,
+                                        "captureScreen: error waiting on EGL fence: %#x", eglErr);
+                            }
+                        } else {
+                            ALOGW("captureScreen: error creating EGL fence: %#x", eglGetError());
+                            // not fatal
+                        }
+
                         if (DEBUG_SCREENSHOTS) {
                             uint32_t* pixels = new uint32_t[reqWidth*reqHeight];
                             getRenderEngine().readPixels(0, 0, reqWidth, reqHeight, pixels);