diff --git a/include/gui/DisplayEventReceiver.h b/include/gui/DisplayEventReceiver.h
index a281377..7bca8d6 100644
--- a/include/gui/DisplayEventReceiver.h
+++ b/include/gui/DisplayEventReceiver.h
@@ -95,6 +95,8 @@
      * should be destroyed and getEvents() shouldn't be called again.
      */
     ssize_t getEvents(Event* events, size_t count);
+    static ssize_t getEvents(const sp<BitTube>& dataChannel,
+            Event* events, size_t count);
 
     /*
      * setVsyncRate() sets the Event::VSync delivery rate. A value of
diff --git a/include/utils/threads.h b/include/utils/threads.h
index ab3e8cd..b4a8b7c 100644
--- a/include/utils/threads.h
+++ b/include/utils/threads.h
@@ -526,6 +526,12 @@
     // Do not call from this object's thread; will return WOULD_BLOCK in that case.
             status_t    join();
 
+#ifdef HAVE_ANDROID_OS
+    // Return the thread's kernel ID, same as the thread itself calling gettid() or
+    // androidGetTid(), or -1 if the thread is not running.
+            pid_t       getTid() const;
+#endif
+
 protected:
     // exitPending() returns true if requestExit() has been called.
             bool        exitPending() const;
@@ -551,8 +557,10 @@
     volatile bool           mExitPending;
     volatile bool           mRunning;
             sp<Thread>      mHoldSelf;
-#if HAVE_ANDROID_OS
-            int             mTid;
+#ifdef HAVE_ANDROID_OS
+    // legacy for debugging, not used by getTid() as it is set by the child thread
+    // and so is not initialized until the child reaches that point
+            pid_t           mTid;
 #endif
 };
 
diff --git a/libs/gui/DisplayEventReceiver.cpp b/libs/gui/DisplayEventReceiver.cpp
index 3b3ccaa..6a4763d 100644
--- a/libs/gui/DisplayEventReceiver.cpp
+++ b/libs/gui/DisplayEventReceiver.cpp
@@ -80,7 +80,13 @@
 
 ssize_t DisplayEventReceiver::getEvents(DisplayEventReceiver::Event* events,
         size_t count) {
-    ssize_t size = mDataChannel->read(events, sizeof(events[0])*count);
+    return DisplayEventReceiver::getEvents(mDataChannel, events, count);
+}
+
+ssize_t DisplayEventReceiver::getEvents(const sp<BitTube>& dataChannel,
+        Event* events, size_t count)
+{
+    ssize_t size = dataChannel->read(events, sizeof(events[0])*count);
     ALOGE_IF(size<0,
             "DisplayEventReceiver::getEvents error (%s)",
             strerror(-size));
diff --git a/libs/utils/Android.mk b/libs/utils/Android.mk
index 544ab74..24cf504 100644
--- a/libs/utils/Android.mk
+++ b/libs/utils/Android.mk
@@ -98,7 +98,8 @@
 
 LOCAL_C_INCLUDES += \
 		external/zlib \
-		external/icu4c/common
+		external/icu4c/common \
+		bionic/libc/private
 
 LOCAL_LDLIBS += -lpthread
 
@@ -114,7 +115,10 @@
 
 ifeq ($(TARGET_OS),linux)
 include $(CLEAR_VARS)
-LOCAL_C_INCLUDES += external/zlib external/icu4c/common
+LOCAL_C_INCLUDES += \
+		external/zlib \
+		external/icu4c/common \
+		bionic/libc/private
 LOCAL_LDLIBS := -lrt -ldl -lpthread
 LOCAL_MODULE := libutils
 LOCAL_SRC_FILES := $(commonSources) BackupData.cpp BackupHelpers.cpp
diff --git a/libs/utils/Threads.cpp b/libs/utils/Threads.cpp
index e343c62..ab207f5 100644
--- a/libs/utils/Threads.cpp
+++ b/libs/utils/Threads.cpp
@@ -34,6 +34,9 @@
 # include <pthread.h>
 # include <sched.h>
 # include <sys/resource.h>
+#ifdef HAVE_ANDROID_OS
+# include <bionic_pthread.h>
+#endif
 #elif defined(HAVE_WIN32_THREADS)
 # include <windows.h>
 # include <stdint.h>
@@ -86,7 +89,7 @@
     char *          threadName;
 
     // we use this trampoline when we need to set the priority with
-    // nice/setpriority.
+    // nice/setpriority, and name with prctl.
     static int trampoline(const thread_data_t* t) {
         thread_func_t f = t->entryFunction;
         void* u = t->userData;
@@ -141,8 +144,13 @@
 
 #ifdef HAVE_ANDROID_OS  /* valgrind is rejecting RT-priority create reqs */
     if (threadPriority != PRIORITY_DEFAULT || threadName != NULL) {
-        // We could avoid the trampoline if there was a way to get to the
-        // android_thread_id_t (pid) from pthread_t
+        // Now that the pthread_t has a method to find the associated
+        // android_thread_id_t (pid) from pthread_t, it would be possible to avoid
+        // this trampoline in some cases as the parent could set the properties
+        // for the child.  However, there would be a race condition because the
+        // child becomes ready immediately, and it doesn't work for the name.
+        // prctl(PR_SET_NAME) only works for self; prctl(PR_SET_THREAD_NAME) was
+        // proposed but not yet accepted.
         thread_data_t* t = new thread_data_t;
         t->priority = threadPriority;
         t->threadName = threadName ? strdup(threadName) : NULL;
@@ -178,6 +186,13 @@
     return 1;
 }
 
+#ifdef HAVE_ANDROID_OS
+static pthread_t android_thread_id_t_to_pthread(android_thread_id_t thread)
+{
+    return (pthread_t) thread;
+}
+#endif
+
 android_thread_id_t androidGetThreadId()
 {
     return (android_thread_id_t)pthread_self();
@@ -909,6 +924,23 @@
     return mStatus;
 }
 
+#ifdef HAVE_ANDROID_OS
+pid_t Thread::getTid() const
+{
+    // mTid is not defined until the child initializes it, and the caller may need it earlier
+    Mutex::Autolock _l(mLock);
+    pid_t tid;
+    if (mRunning) {
+        pthread_t pthread = android_thread_id_t_to_pthread(mThread);
+        tid = __pthread_gettid(pthread);
+    } else {
+        ALOGW("Thread (this=%p): getTid() is undefined before run()", this);
+        tid = -1;
+    }
+    return tid;
+}
+#endif
+
 bool Thread::exitPending() const
 {
     Mutex::Autolock _l(mLock);
diff --git a/services/surfaceflinger/Android.mk b/services/surfaceflinger/Android.mk
index fc211e5..8b4c074 100644
--- a/services/surfaceflinger/Android.mk
+++ b/services/surfaceflinger/Android.mk
@@ -32,7 +32,6 @@
 endif
 ifeq ($(TARGET_BOARD_PLATFORM), omap4)
 	LOCAL_CFLAGS += -DHAS_CONTEXT_PRIORITY
-	LOCAL_CFLAGS += -DUSE_TRIPLE_BUFFERING=1
 endif
 ifeq ($(TARGET_BOARD_PLATFORM), s5pc110)
 	LOCAL_CFLAGS += -DHAS_CONTEXT_PRIORITY -DNEVER_DEFAULT_TO_ASYNC_MODE
diff --git a/services/surfaceflinger/DisplayHardware/DisplayHardwareBase.cpp b/services/surfaceflinger/DisplayHardware/DisplayHardwareBase.cpp
index f4afeea..09f1906 100644
--- a/services/surfaceflinger/DisplayHardware/DisplayHardwareBase.cpp
+++ b/services/surfaceflinger/DisplayHardware/DisplayHardwareBase.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2007 The Android Open Source Project
+ * Copyright (C) 2012 The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -14,7 +14,6 @@
  * limitations under the License.
  */
 
-#include <assert.h>
 #include <errno.h>
 #include <stdlib.h>
 #include <stdio.h>
@@ -22,15 +21,6 @@
 
 #include <unistd.h>
 #include <fcntl.h>
-#include <signal.h>
-#include <termios.h>
-#include <sys/ioctl.h>
-#include <sys/mman.h>
-#include <sys/time.h>
-#include <sys/types.h>
-#include <sys/resource.h>
-
-#include <linux/unistd.h>
 
 #include <utils/Log.h>
 
@@ -45,39 +35,30 @@
 
 // ----------------------------------------------------------------------------
 
-DisplayHardwareBase::DisplayEventThreadBase::DisplayEventThreadBase(
+DisplayHardwareBase::DisplayEventThread::DisplayEventThread(
         const sp<SurfaceFlinger>& flinger)
     : Thread(false), mFlinger(flinger) {
 }
 
-DisplayHardwareBase::DisplayEventThreadBase::~DisplayEventThreadBase() {
+DisplayHardwareBase::DisplayEventThread::~DisplayEventThread() {
 }
 
-// ----------------------------------------------------------------------------
-
-DisplayHardwareBase::DisplayEventThread::DisplayEventThread(
-        const sp<SurfaceFlinger>& flinger)
-    : DisplayEventThreadBase(flinger)
-{
+void DisplayHardwareBase::DisplayEventThread::onFirstRef() {
+    if (initCheck() == NO_ERROR) {
+        run("DisplayEventThread", PRIORITY_URGENT_DISPLAY);
+    } else {
+        ALOGW("/sys/power/wait_for_fb_{wake|sleep} don't exist");
+    }
 }
 
-DisplayHardwareBase::DisplayEventThread::~DisplayEventThread()
-{
+status_t DisplayHardwareBase::DisplayEventThread::initCheck() const {
+    return ((access(kSleepFileName, R_OK) == 0 &&
+            access(kWakeFileName, R_OK) == 0)) ? NO_ERROR : NO_INIT;
 }
 
-bool DisplayHardwareBase::DisplayEventThread::threadLoop()
-{
-    int err = 0;
-    char buf;
-    int fd;
+bool DisplayHardwareBase::DisplayEventThread::threadLoop() {
 
-    fd = open(kSleepFileName, O_RDONLY, 0);
-    do {
-      err = read(fd, &buf, 1);
-    } while (err < 0 && errno == EINTR);
-    close(fd);
-    ALOGW_IF(err<0, "ANDROID_WAIT_FOR_FB_SLEEP failed (%s)", strerror(errno));
-    if (err >= 0) {
+    if (waitForFbSleep() == NO_ERROR) {
         sp<SurfaceFlinger> flinger = mFlinger.promote();
         ALOGD("About to give-up screen, flinger = %p", flinger.get());
         if (flinger != 0) {
@@ -85,39 +66,51 @@
             flinger->screenReleased(0);
             mBarrier.wait();
         }
+        if (waitForFbWake() == NO_ERROR) {
+            sp<SurfaceFlinger> flinger = mFlinger.promote();
+            ALOGD("Screen about to return, flinger = %p", flinger.get());
+            if (flinger != 0) {
+                flinger->screenAcquired(0);
+            }
+            return true;
+        }
     }
-    fd = open(kWakeFileName, O_RDONLY, 0);
+
+    // error, exit the thread
+    return false;
+}
+
+status_t DisplayHardwareBase::DisplayEventThread::waitForFbSleep() {
+    int err = 0;
+    char buf;
+    int fd = open(kSleepFileName, O_RDONLY, 0);
+    // if the file doesn't exist, the error will be caught in read() below
     do {
-      err = read(fd, &buf, 1);
+        err = read(fd, &buf, 1);
     } while (err < 0 && errno == EINTR);
     close(fd);
-    ALOGW_IF(err<0, "ANDROID_WAIT_FOR_FB_WAKE failed (%s)", strerror(errno));
-    if (err >= 0) {
-        sp<SurfaceFlinger> flinger = mFlinger.promote();
-        ALOGD("Screen about to return, flinger = %p", flinger.get());
-        if (flinger != 0)
-            flinger->screenAcquired(0);
-    }
-    return true;
+    ALOGE_IF(err<0, "*** ANDROID_WAIT_FOR_FB_SLEEP failed (%s)", strerror(errno));
+    return err < 0 ? -errno : int(NO_ERROR);
 }
 
-status_t DisplayHardwareBase::DisplayEventThread::releaseScreen() const
-{
+status_t DisplayHardwareBase::DisplayEventThread::waitForFbWake() {
+    int err = 0;
+    char buf;
+    int fd = open(kWakeFileName, O_RDONLY, 0);
+    // if the file doesn't exist, the error will be caught in read() below
+    do {
+        err = read(fd, &buf, 1);
+    } while (err < 0 && errno == EINTR);
+    close(fd);
+    ALOGE_IF(err<0, "*** ANDROID_WAIT_FOR_FB_WAKE failed (%s)", strerror(errno));
+    return err < 0 ? -errno : int(NO_ERROR);
+}
+
+status_t DisplayHardwareBase::DisplayEventThread::releaseScreen() const {
     mBarrier.open();
     return NO_ERROR;
 }
 
-status_t DisplayHardwareBase::DisplayEventThread::readyToRun()
-{
-    return NO_ERROR;
-}
-
-status_t DisplayHardwareBase::DisplayEventThread::initCheck() const
-{
-    return ((access(kSleepFileName, R_OK) == 0 &&
-            access(kWakeFileName, R_OK) == 0)) ? NO_ERROR : NO_INIT;
-}
-
 // ----------------------------------------------------------------------------
 
 DisplayHardwareBase::DisplayHardwareBase(const sp<SurfaceFlinger>& flinger,
@@ -127,35 +120,27 @@
     mDisplayEventThread = new DisplayEventThread(flinger);
 }
 
-DisplayHardwareBase::~DisplayHardwareBase()
-{
+DisplayHardwareBase::~DisplayHardwareBase() {
     // request exit
     mDisplayEventThread->requestExitAndWait();
 }
 
-bool DisplayHardwareBase::canDraw() const
-{
+bool DisplayHardwareBase::canDraw() const {
     return mScreenAcquired;
 }
 
-void DisplayHardwareBase::releaseScreen() const
-{
+void DisplayHardwareBase::releaseScreen() const {
     status_t err = mDisplayEventThread->releaseScreen();
     if (err >= 0) {
         mScreenAcquired = false;
     }
 }
 
-void DisplayHardwareBase::acquireScreen() const
-{
-    status_t err = mDisplayEventThread->acquireScreen();
-    if (err >= 0) {
-        mScreenAcquired = true;
-    }
+void DisplayHardwareBase::acquireScreen() const {
+    mScreenAcquired = true;
 }
 
-bool DisplayHardwareBase::isScreenAcquired() const
-{
+bool DisplayHardwareBase::isScreenAcquired() const {
     return mScreenAcquired;
 }
 
diff --git a/services/surfaceflinger/DisplayHardware/DisplayHardwareBase.h b/services/surfaceflinger/DisplayHardware/DisplayHardwareBase.h
index ef2df43..91ea602 100644
--- a/services/surfaceflinger/DisplayHardware/DisplayHardwareBase.h
+++ b/services/surfaceflinger/DisplayHardware/DisplayHardwareBase.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2007 The Android Open Source Project
+ * Copyright (C) 2012 The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -20,8 +20,6 @@
 #include <stdint.h>
 #include <utils/RefBase.h>
 #include <utils/threads.h>
-#include <linux/kd.h>
-#include <linux/vt.h>
 #include "Barrier.h"
 
 namespace android {
@@ -31,11 +29,11 @@
 class DisplayHardwareBase
 {
 public:
-                DisplayHardwareBase(
-                        const sp<SurfaceFlinger>& flinger,
-                        uint32_t displayIndex);
+    DisplayHardwareBase(
+            const sp<SurfaceFlinger>& flinger,
+            uint32_t displayIndex);
 
-                ~DisplayHardwareBase();
+    ~DisplayHardwareBase();
 
     // console management
     void releaseScreen() const;
@@ -46,34 +44,22 @@
 
 
 private:
-    class DisplayEventThreadBase : public Thread {
-    protected:
+    class DisplayEventThread : public Thread {
         wp<SurfaceFlinger> mFlinger;
-    public:
-        DisplayEventThreadBase(const sp<SurfaceFlinger>& flinger);
-        virtual ~DisplayEventThreadBase();
-        virtual void onFirstRef() {
-            run("DisplayEventThread", PRIORITY_URGENT_DISPLAY);
-        }
-        virtual status_t acquireScreen() const { return NO_ERROR; };
-        virtual status_t releaseScreen() const { return NO_ERROR; };
-        virtual status_t initCheck() const = 0;
-    };
-
-    class DisplayEventThread : public DisplayEventThreadBase 
-    {
         mutable Barrier mBarrier;
+        status_t waitForFbSleep();
+        status_t waitForFbWake();
     public:
-                DisplayEventThread(const sp<SurfaceFlinger>& flinger);
+        DisplayEventThread(const sp<SurfaceFlinger>& flinger);
         virtual ~DisplayEventThread();
+        virtual void onFirstRef();
         virtual bool threadLoop();
-        virtual status_t readyToRun();
-        virtual status_t releaseScreen() const;
-        virtual status_t initCheck() const;
+        status_t releaseScreen() const;
+        status_t initCheck() const;
     };
 
-    sp<DisplayEventThreadBase>  mDisplayEventThread;
-    mutable int                 mScreenAcquired;
+    sp<DisplayEventThread>  mDisplayEventThread;
+    mutable int             mScreenAcquired;
 };
 
 }; // namespace android
diff --git a/services/surfaceflinger/Layer.cpp b/services/surfaceflinger/Layer.cpp
index 9c04d59..64f72d5 100644
--- a/services/surfaceflinger/Layer.cpp
+++ b/services/surfaceflinger/Layer.cpp
@@ -55,6 +55,7 @@
         mCurrentTransform(0),
         mCurrentScalingMode(NATIVE_WINDOW_SCALING_MODE_FREEZE),
         mCurrentOpacity(true),
+        mRefreshPending(0),
         mFrameLatencyNeeded(false),
         mFrameLatencyOffset(0),
         mFormat(PIXEL_FORMAT_NONE),
@@ -97,12 +98,7 @@
     mSurfaceTexture = new SurfaceTextureLayer(mTextureName, this);
     mSurfaceTexture->setFrameAvailableListener(new FrameQueuedListener(this));
     mSurfaceTexture->setSynchronousMode(true);
-#ifdef USE_TRIPLE_BUFFERING
-#warning "using triple buffering"
-    mSurfaceTexture->setBufferCountServer(3);
-#else
     mSurfaceTexture->setBufferCountServer(2);
-#endif
 }
 
 Layer::~Layer()
@@ -113,7 +109,7 @@
 
 void Layer::onFrameQueued() {
     android_atomic_inc(&mQueuedFrames);
-    mFlinger->signalEvent();
+    mFlinger->signalLayerUpdate();
 }
 
 // called with SurfaceFlinger::mStateLock as soon as the layer is entered
@@ -407,16 +403,37 @@
 // pageflip handling...
 // ----------------------------------------------------------------------------
 
+bool Layer::onPreComposition()
+{
+    // if there was more than one pending update, request a refresh
+    if (mRefreshPending >= 2) {
+        mRefreshPending = 0;
+        return true;
+    }
+    mRefreshPending = 0;
+    return false;
+}
+
 void Layer::lockPageFlip(bool& recomputeVisibleRegions)
 {
     if (mQueuedFrames > 0) {
+
+        // if we've already called updateTexImage() without going through
+        // a composition step, we have to skip this layer at this point
+        // because we cannot call updateTeximage() without a corresponding
+        // compositionComplete() call.
+        // we'll trigger an update in onPreComposition().
+        if (mRefreshPending++) {
+            return;
+        }
+
         // Capture the old state of the layer for comparisons later
         const bool oldOpacity = isOpaque();
         sp<GraphicBuffer> oldActiveBuffer = mActiveBuffer;
 
         // signal another event if we have more frames pending
         if (android_atomic_dec(&mQueuedFrames) > 1) {
-            mFlinger->signalEvent();
+            mFlinger->signalLayerUpdate();
         }
 
         if (mSurfaceTexture->updateTexImage() < NO_ERROR) {
@@ -519,6 +536,10 @@
 void Layer::unlockPageFlip(
         const Transform& planeTransform, Region& outDirtyRegion)
 {
+    if (mRefreshPending >= 2) {
+        return;
+    }
+
     Region dirtyRegion(mPostedDirtyRegion);
     if (!dirtyRegion.isEmpty()) {
         mPostedDirtyRegion.clear();
@@ -552,9 +573,9 @@
     snprintf(buffer, SIZE,
             "      "
             "format=%2d, activeBuffer=[%4ux%4u:%4u,%3X],"
-            " transform-hint=0x%02x, queued-frames=%d\n",
+            " transform-hint=0x%02x, queued-frames=%d, mRefreshPending=%d\n",
             mFormat, w0, h0, s0,f0,
-            getTransformHint(), mQueuedFrames);
+            getTransformHint(), mQueuedFrames, mRefreshPending);
 
     result.append(buffer);
 
diff --git a/services/surfaceflinger/Layer.h b/services/surfaceflinger/Layer.h
index 2dd4da1..bf30608 100644
--- a/services/surfaceflinger/Layer.h
+++ b/services/surfaceflinger/Layer.h
@@ -80,6 +80,7 @@
     virtual wp<IBinder> getSurfaceTextureBinder() const;
 
     virtual void onLayerDisplayed();
+    virtual bool onPreComposition();
 
     // only for debugging
     inline const sp<GraphicBuffer>& getActiveBuffer() const { return mActiveBuffer; }
@@ -115,14 +116,17 @@
     uint32_t mCurrentTransform;
     uint32_t mCurrentScalingMode;
     bool mCurrentOpacity;
+    size_t mRefreshPending;
     bool mFrameLatencyNeeded;
     int mFrameLatencyOffset;
+
     struct Statistics {
         Statistics() : timestamp(0), set(0), vsync(0) { }
         nsecs_t timestamp;  // buffer timestamp
         nsecs_t set;        // buffer displayed timestamp
         nsecs_t vsync;      // vsync immediately before set
     };
+
     // protected by mLock
     Statistics mFrameStats[128];
 
diff --git a/services/surfaceflinger/LayerBase.cpp b/services/surfaceflinger/LayerBase.cpp
index d32fcdd..44aafdf 100644
--- a/services/surfaceflinger/LayerBase.cpp
+++ b/services/surfaceflinger/LayerBase.cpp
@@ -47,8 +47,7 @@
       mOrientation(0),
       mPlaneOrientation(0),
       mTransactionFlags(0),
-      mPremultipliedAlpha(true), mName("unnamed"), mDebug(false),
-      mInvalidate(0)
+      mPremultipliedAlpha(true), mName("unnamed"), mDebug(false)
 {
     const DisplayHardware& hw(flinger->graphicPlane(0).displayHardware());
     mFlags = hw.getFlags();
@@ -262,23 +261,11 @@
     mTransformedBounds = tr.makeBounds(w, h);
 }
 
-void LayerBase::lockPageFlip(bool& recomputeVisibleRegions)
-{
+void LayerBase::lockPageFlip(bool& recomputeVisibleRegions) {
 }
 
 void LayerBase::unlockPageFlip(
-        const Transform& planeTransform, Region& outDirtyRegion)
-{
-    if ((android_atomic_and(~1, &mInvalidate)&1) == 1) {
-        outDirtyRegion.orSelf(visibleRegionScreen);
-    }
-}
-
-void LayerBase::invalidate()
-{
-    if ((android_atomic_or(1, &mInvalidate)&1) == 0) {
-        mFlinger->signalEvent();
-    }
+        const Transform& planeTransform, Region& outDirtyRegion) {
 }
 
 void LayerBase::drawRegion(const Region& reg) const
diff --git a/services/surfaceflinger/LayerBase.h b/services/surfaceflinger/LayerBase.h
index 6b62c9d..b8f7680 100644
--- a/services/surfaceflinger/LayerBase.h
+++ b/services/surfaceflinger/LayerBase.h
@@ -103,8 +103,6 @@
             Rect visibleBounds() const;
             void drawRegion(const Region& reg) const;
 
-            void invalidate();
-
     virtual sp<LayerBaseClient> getLayerBaseClient() const { return 0; }
     virtual sp<Layer> getLayer() const { return 0; }
 
@@ -204,9 +202,16 @@
 
     /** called with the state lock when the surface is removed from the
      *  current list */
-    virtual void onRemoved() { };
+    virtual void onRemoved() { }
 
-    virtual void onLayerDisplayed() { };
+    /** called after page-flip
+     */
+    virtual void onLayerDisplayed() { }
+
+    /** called before composition.
+     * returns true if the layer has pending updates.
+     */
+    virtual bool onPreComposition() { return false; }
 
     /** always call base class first */
     virtual void dump(String8& result, char* scratch, size_t size) const;
@@ -275,10 +280,6 @@
     mutable     bool            mDebug;
 
 
-                // atomic
-    volatile    int32_t         mInvalidate;
-                
-
 public:
     // called from class SurfaceFlinger
     virtual ~LayerBase();
diff --git a/services/surfaceflinger/MessageQueue.cpp b/services/surfaceflinger/MessageQueue.cpp
index 70711e7..1ff3567 100644
--- a/services/surfaceflinger/MessageQueue.cpp
+++ b/services/surfaceflinger/MessageQueue.cpp
@@ -29,6 +29,7 @@
 
 #include "MessageQueue.h"
 #include "EventThread.h"
+#include "SurfaceFlinger.h"
 
 namespace android {
 
@@ -48,14 +49,47 @@
 
 // ---------------------------------------------------------------------------
 
+void MessageQueue::Handler::signalRefresh() {
+    if ((android_atomic_or(eventMaskRefresh, &mEventMask) & eventMaskRefresh) == 0) {
+        mQueue.mLooper->sendMessage(this, Message(MessageQueue::REFRESH));
+    }
+}
+
+void MessageQueue::Handler::signalInvalidate() {
+    if ((android_atomic_or(eventMaskInvalidate, &mEventMask) & eventMaskInvalidate) == 0) {
+        mQueue.mLooper->sendMessage(this, Message(MessageQueue::INVALIDATE));
+    }
+}
+
+void MessageQueue::Handler::handleMessage(const Message& message) {
+    switch (message.what) {
+        case INVALIDATE:
+            android_atomic_and(~eventMaskInvalidate, &mEventMask);
+            mQueue.mFlinger->onMessageReceived(message.what);
+            break;
+        case REFRESH:
+            android_atomic_and(~eventMaskRefresh, &mEventMask);
+            mQueue.mFlinger->onMessageReceived(message.what);
+            break;
+    }
+}
+
+// ---------------------------------------------------------------------------
+
 MessageQueue::MessageQueue()
-    : mLooper(new Looper(true)), mWorkPending(0)
 {
 }
 
 MessageQueue::~MessageQueue() {
 }
 
+void MessageQueue::init(const sp<SurfaceFlinger>& flinger)
+{
+    mFlinger = flinger;
+    mLooper = new Looper(true);
+    mHandler = new Handler(*this);
+}
+
 void MessageQueue::setEventThread(const sp<EventThread>& eventThread)
 {
     mEventThread = eventThread;
@@ -68,25 +102,16 @@
 void MessageQueue::waitMessage() {
     do {
         IPCThreadState::self()->flushCommands();
-
         int32_t ret = mLooper->pollOnce(-1);
         switch (ret) {
             case ALOOPER_POLL_WAKE:
             case ALOOPER_POLL_CALLBACK:
-                // callback and/or wake
-                if (android_atomic_and(0, &mWorkPending)) {
-                    return;
-                }
                 continue;
-
+            case ALOOPER_POLL_ERROR:
+                ALOGE("ALOOPER_POLL_ERROR");
             case ALOOPER_POLL_TIMEOUT:
                 // timeout (should not happen)
                 continue;
-
-            case ALOOPER_POLL_ERROR:
-                ALOGE("ALOOPER_POLL_ERROR");
-                continue;
-
             default:
                 // should not happen
                 ALOGE("Looper::pollOnce() returned unknown status %d", ret);
@@ -107,15 +132,12 @@
     return NO_ERROR;
 }
 
-void MessageQueue::scheduleWorkASAP() {
-    if (android_atomic_or(1, &mWorkPending) == 0) {
-        mLooper->wake();
-   }
+void MessageQueue::invalidate() {
+    mHandler->signalInvalidate();
 }
 
-status_t MessageQueue::invalidate() {
+void MessageQueue::refresh() {
     mEvents->requestNextVsync();
-    return NO_ERROR;
 }
 
 int MessageQueue::cb_eventReceiver(int fd, int events, void* data) {
@@ -126,10 +148,10 @@
 int MessageQueue::eventReceiver(int fd, int events) {
     ssize_t n;
     DisplayEventReceiver::Event buffer[8];
-    while ((n = getEvents(buffer, 8)) > 0) {
+    while ((n = DisplayEventReceiver::getEvents(mEventTube, buffer, 8)) > 0) {
         for (int i=0 ; i<n ; i++) {
             if (buffer[i].header.type == DisplayEventReceiver::DISPLAY_EVENT_VSYNC) {
-                scheduleWorkASAP();
+                mHandler->signalRefresh();
                 break;
             }
         }
@@ -137,24 +159,6 @@
     return 1;
 }
 
-ssize_t MessageQueue::getEvents(
-        DisplayEventReceiver::Event* events, size_t count)
-{
-    ssize_t size = mEventTube->read(events, sizeof(events[0])*count);
-    ALOGE_IF(size<0, "MessageQueue::getEvents error (%s)", strerror(-size));
-    if (size >= 0) {
-        // Note: if (size % sizeof(events[0])) != 0, we've got a
-        // partial read. This can happen if the queue filed up (ie: if we
-        // didn't pull from it fast enough).
-        // We discard the partial event and rely on the sender to
-        // re-send the event if appropriate (some events, like VSYNC
-        // can be lost forever).
-        // returns number of events read
-        size /= sizeof(events[0]);
-    }
-    return size;
-}
-
 // ---------------------------------------------------------------------------
 
 }; // namespace android
diff --git a/services/surfaceflinger/MessageQueue.h b/services/surfaceflinger/MessageQueue.h
index 5ea197d..ea29e7e 100644
--- a/services/surfaceflinger/MessageQueue.h
+++ b/services/surfaceflinger/MessageQueue.h
@@ -33,6 +33,7 @@
 
 class IDisplayEventConnection;
 class EventThread;
+class SurfaceFlinger;
 
 // ---------------------------------------------------------------------------
 
@@ -59,25 +60,48 @@
 // ---------------------------------------------------------------------------
 
 class MessageQueue {
+    class Handler : public MessageHandler {
+        enum {
+            eventMaskInvalidate = 0x1,
+            eventMaskRefresh    = 0x2
+        };
+        MessageQueue& mQueue;
+        int32_t mEventMask;
+    public:
+        Handler(MessageQueue& queue) : mQueue(queue), mEventMask(0) { }
+        virtual void handleMessage(const Message& message);
+        void signalRefresh();
+        void signalInvalidate();
+    };
+
+    friend class Handler;
+
+    sp<SurfaceFlinger> mFlinger;
     sp<Looper> mLooper;
     sp<EventThread> mEventThread;
     sp<IDisplayEventConnection> mEvents;
     sp<BitTube> mEventTube;
-    int32_t mWorkPending;
+    sp<Handler> mHandler;
+
 
     static int cb_eventReceiver(int fd, int events, void* data);
     int eventReceiver(int fd, int events);
-    ssize_t getEvents(DisplayEventReceiver::Event* events, size_t count);
-    void scheduleWorkASAP();
 
 public:
+    enum {
+        INVALIDATE = 0,
+        REFRESH    = 1,
+    };
+
     MessageQueue();
     ~MessageQueue();
+    void init(const sp<SurfaceFlinger>& flinger);
     void setEventThread(const sp<EventThread>& events);
 
     void waitMessage();
     status_t postMessage(const sp<MessageBase>& message, nsecs_t reltime=0);
-    status_t invalidate();
+    void invalidate();
+    void refresh();
 };
 
 // ---------------------------------------------------------------------------
diff --git a/services/surfaceflinger/SurfaceFlinger.cpp b/services/surfaceflinger/SurfaceFlinger.cpp
index ff70ec3..870235b 100644
--- a/services/surfaceflinger/SurfaceFlinger.cpp
+++ b/services/surfaceflinger/SurfaceFlinger.cpp
@@ -125,11 +125,34 @@
     ALOGI_IF(mDebugDDMS,         "DDMS debugging enabled");
 }
 
+void SurfaceFlinger::onFirstRef()
+{
+    mEventQueue.init(this);
+
+    run("SurfaceFlinger", PRIORITY_URGENT_DISPLAY);
+
+    // Wait for the main thread to be done with its initialization
+    mReadyToRunBarrier.wait();
+}
+
+
 SurfaceFlinger::~SurfaceFlinger()
 {
     glDeleteTextures(1, &mWormholeTexName);
 }
 
+void SurfaceFlinger::binderDied(const wp<IBinder>& who)
+{
+    // the window manager died on us. prepare its eulogy.
+
+    // reset screen orientation
+    Vector<ComposerState> state;
+    setTransactionState(state, eOrientationDefault, 0);
+
+    // restart the boot-animation
+    property_set("ctl.start", "bootanim");
+}
+
 sp<IMemoryHeap> SurfaceFlinger::getCblk() const
 {
     return mServerHeap;
@@ -183,26 +206,6 @@
     property_set("ctl.stop", "bootanim");
 }
 
-void SurfaceFlinger::binderDied(const wp<IBinder>& who)
-{
-    // the window manager died on us. prepare its eulogy.
-
-    // reset screen orientation
-    Vector<ComposerState> state;
-    setTransactionState(state, eOrientationDefault, 0);
-
-    // restart the boot-animation
-    property_set("ctl.start", "bootanim");
-}
-
-void SurfaceFlinger::onFirstRef()
-{
-    run("SurfaceFlinger", PRIORITY_URGENT_DISPLAY);
-
-    // Wait for the main thread to be done with its initialization
-    mReadyToRunBarrier.wait();
-}
-
 static inline uint16_t pack565(int r, int g, int b) {
     return (r<<11)|(g<<5)|b;
 }
@@ -311,34 +314,6 @@
 }
 
 // ----------------------------------------------------------------------------
-#if 0
-#pragma mark -
-#pragma mark Events Handler
-#endif
-
-void SurfaceFlinger::waitForEvent() {
-    mEventQueue.waitMessage();
-}
-
-void SurfaceFlinger::signalEvent() {
-    mEventQueue.invalidate();
-}
-
-status_t SurfaceFlinger::postMessageAsync(const sp<MessageBase>& msg,
-        nsecs_t reltime, uint32_t flags) {
-    return mEventQueue.postMessage(msg, reltime);
-}
-
-status_t SurfaceFlinger::postMessageSync(const sp<MessageBase>& msg,
-        nsecs_t reltime, uint32_t flags) {
-    status_t res = mEventQueue.postMessage(msg, reltime);
-    if (res == NO_ERROR) {
-        msg->wait();
-    }
-    return res;
-}
-
-// ----------------------------------------------------------------------------
 
 bool SurfaceFlinger::authenticateSurfaceTexture(
         const sp<ISurfaceTexture>& surfaceTexture) const {
@@ -388,54 +363,93 @@
 }
 
 // ----------------------------------------------------------------------------
-#if 0
-#pragma mark -
-#pragma mark Main loop
-#endif
+
+void SurfaceFlinger::waitForEvent() {
+    mEventQueue.waitMessage();
+}
+
+void SurfaceFlinger::signalTransaction() {
+    mEventQueue.invalidate();
+}
+
+void SurfaceFlinger::signalLayerUpdate() {
+    mEventQueue.invalidate();
+}
+
+void SurfaceFlinger::signalRefresh() {
+    mEventQueue.refresh();
+}
+
+status_t SurfaceFlinger::postMessageAsync(const sp<MessageBase>& msg,
+        nsecs_t reltime, uint32_t flags) {
+    return mEventQueue.postMessage(msg, reltime);
+}
+
+status_t SurfaceFlinger::postMessageSync(const sp<MessageBase>& msg,
+        nsecs_t reltime, uint32_t flags) {
+    status_t res = mEventQueue.postMessage(msg, reltime);
+    if (res == NO_ERROR) {
+        msg->wait();
+    }
+    return res;
+}
 
 bool SurfaceFlinger::threadLoop()
 {
     waitForEvent();
-
-    // check for transactions
-    if (CC_UNLIKELY(mConsoleSignals)) {
-        handleConsoleEvents();
-    }
-
-    // if we're in a global transaction, don't do anything.
-    const uint32_t mask = eTransactionNeeded | eTraversalNeeded;
-    uint32_t transactionFlags = peekTransactionFlags(mask);
-    if (CC_UNLIKELY(transactionFlags)) {
-        handleTransaction(transactionFlags);
-    }
-
-    // post surfaces (if needed)
-    handlePageFlip();
-
-    if (mDirtyRegion.isEmpty()) {
-        // nothing new to do.
-        return true;
-    }
-
-    if (CC_UNLIKELY(mHwWorkListDirty)) {
-        // build the h/w work list
-        handleWorkList();
-    }
-
-    const DisplayHardware& hw(graphicPlane(0).displayHardware());
-    if (CC_LIKELY(hw.canDraw())) {
-        // repaint the framebuffer (if needed)
-        handleRepaint();
-        // inform the h/w that we're done compositing
-        hw.compositionComplete();
-        postFramebuffer();
-    } else {
-        // pretend we did the post
-        hw.compositionComplete();
-    }
     return true;
 }
 
+void SurfaceFlinger::onMessageReceived(int32_t what)
+{
+    switch (what) {
+        case MessageQueue::INVALIDATE: {
+            // check for transactions
+            if (CC_UNLIKELY(mConsoleSignals)) {
+                handleConsoleEvents();
+            }
+
+            // if we're in a global transaction, don't do anything.
+            const uint32_t mask = eTransactionNeeded | eTraversalNeeded;
+            uint32_t transactionFlags = peekTransactionFlags(mask);
+            if (CC_UNLIKELY(transactionFlags)) {
+                handleTransaction(transactionFlags);
+            }
+
+            // post surfaces (if needed)
+            handlePageFlip();
+
+            if (!mDirtyRegion.isEmpty()) {
+                signalRefresh();
+            }
+        } break;
+
+        case MessageQueue::REFRESH: {
+            if (!mDirtyRegion.isEmpty()) {
+                // NOTE: it is mandatory to call hw.compositionComplete()
+                // after handleRefresh()
+                handleRefresh();
+
+                const DisplayHardware& hw(graphicPlane(0).displayHardware());
+                if (CC_UNLIKELY(mHwWorkListDirty)) {
+                    // build the h/w work list
+                    handleWorkList();
+                }
+                if (CC_LIKELY(hw.canDraw())) {
+                    // repaint the framebuffer (if needed)
+                    handleRepaint();
+                    // inform the h/w that we're done compositing
+                    hw.compositionComplete();
+                    postFramebuffer();
+                } else {
+                    // pretend we did the post
+                    hw.compositionComplete();
+                }
+            }
+        } break;
+    }
+}
+
 void SurfaceFlinger::postFramebuffer()
 {
     // this should never happen. we do the flip anyways so we don't
@@ -717,13 +731,13 @@
 
 void SurfaceFlinger::handlePageFlip()
 {
-    bool visibleRegions = mVisibleRegionsDirty;
-    const LayerVector& currentLayers(mDrawingState.layersSortedByZ);
-    visibleRegions |= lockPageFlip(currentLayers);
+    const DisplayHardware& hw = graphicPlane(0).displayHardware();
+    const Region screenRegion(hw.bounds());
 
-        const DisplayHardware& hw = graphicPlane(0).displayHardware();
-        const Region screenRegion(hw.bounds());
-        if (visibleRegions) {
+    const LayerVector& currentLayers(mDrawingState.layersSortedByZ);
+    const bool visibleRegions = lockPageFlip(currentLayers);
+
+        if (visibleRegions || mVisibleRegionsDirty) {
             Region opaqueRegion;
             computeVisibleRegions(currentLayers, mDirtyRegion, opaqueRegion);
 
@@ -770,7 +784,7 @@
 {
     const GraphicPlane& plane(graphicPlane(0));
     const Transform& planeTransform(plane.transform());
-    size_t count = currentLayers.size();
+    const size_t count = currentLayers.size();
     sp<LayerBase> const* layers = currentLayers.array();
     for (size_t i=0 ; i<count ; i++) {
         const sp<LayerBase>& layer(layers[i]);
@@ -778,6 +792,23 @@
     }
 }
 
+void SurfaceFlinger::handleRefresh()
+{
+    bool needInvalidate = false;
+    const LayerVector& currentLayers(mDrawingState.layersSortedByZ);
+    const size_t count = currentLayers.size();
+    for (size_t i=0 ; i<count ; i++) {
+        const sp<LayerBase>& layer(currentLayers[i]);
+        if (layer->onPreComposition()) {
+            needInvalidate = true;
+        }
+    }
+    if (needInvalidate) {
+        signalLayerUpdate();
+    }
+}
+
+
 void SurfaceFlinger::handleWorkList()
 {
     mHwWorkListDirty = false;
@@ -1175,7 +1206,7 @@
 {
     uint32_t old = android_atomic_or(flags, &mTransactionFlags);
     if ((old & flags)==0) { // wake the server up
-        signalEvent();
+        signalTransaction();
     }
     return old;
 }
@@ -1426,14 +1457,14 @@
 {
     // this may be called by a signal handler, we can't do too much in here
     android_atomic_or(eConsoleReleased, &mConsoleSignals);
-    signalEvent();
+    signalTransaction();
 }
 
 void SurfaceFlinger::screenAcquired(int dpy)
 {
     // this may be called by a signal handler, we can't do too much in here
     android_atomic_or(eConsoleAcquired, &mConsoleSignals);
-    signalEvent();
+    signalTransaction();
 }
 
 status_t SurfaceFlinger::dump(int fd, const Vector<String16>& args)
@@ -1769,7 +1800,7 @@
     const DisplayHardware& hw(graphicPlane(0).displayHardware());
     const Rect bounds(hw.getBounds());
     setInvalidateRegion(Region(bounds));
-    signalEvent();
+    signalTransaction();
 }
 
 void SurfaceFlinger::setInvalidateRegion(const Region& reg) {
@@ -2245,7 +2276,7 @@
 
     // make sure to redraw the whole screen when the animation is done
     mDirtyRegion.set(hw.bounds());
-    signalEvent();
+    signalTransaction();
 
     return NO_ERROR;
 }
diff --git a/services/surfaceflinger/SurfaceFlinger.h b/services/surfaceflinger/SurfaceFlinger.h
index c24a9de..fcd9361 100644
--- a/services/surfaceflinger/SurfaceFlinger.h
+++ b/services/surfaceflinger/SurfaceFlinger.h
@@ -190,6 +190,8 @@
             status_t renderScreenToTextureLocked(DisplayID dpy,
                     GLuint* textureName, GLfloat* uOut, GLfloat* vOut);
 
+            void onMessageReceived(int32_t what);
+
             status_t postMessageAsync(const sp<MessageBase>& msg,
                     nsecs_t reltime=0, uint32_t flags = 0);
 
@@ -283,7 +285,10 @@
 public:     // hack to work around gcc 4.0.3 bug
     const GraphicPlane&     graphicPlane(int dpy) const;
           GraphicPlane&     graphicPlane(int dpy);
-          void              signalEvent();
+
+          void              signalTransaction();
+          void              signalLayerUpdate();
+          void              signalRefresh();
           void              repaintEverything();
 
 private:
@@ -300,6 +305,7 @@
             void        handlePageFlip();
             bool        lockPageFlip(const LayerVector& currentLayers);
             void        unlockPageFlip(const LayerVector& currentLayers);
+            void        handleRefresh();
             void        handleWorkList();
             void        handleRepaint();
             void        postFramebuffer();