8 files changed, 60 insertions, 6 deletions
diff --git a/libs/gui/BufferQueueConsumer.cpp b/libs/gui/BufferQueueConsumer.cpp
index e2261360b6..528bfb194e 100644
--- a/libs/gui/BufferQueueConsumer.cpp
+++ b/libs/gui/BufferQueueConsumer.cpp
@@ -94,8 +94,6 @@ status_t BufferQueueConsumer::acquireBuffer(BufferItem* outBuffer,
         // Skip this if we're in shared buffer mode and the queue is empty,
         // since in that case we'll just return the shared buffer.
         if (expectedPresent != 0 && !mCore->mQueue.empty()) {
-            const int MAX_REASONABLE_NSEC = 1000000000ULL; // 1 second
-
             // The 'expectedPresent' argument indicates when the buffer is expected
             // to be presented on-screen. If the buffer's desired present time is
             // earlier (less) than expectedPresent -- meaning it will be displayed
diff --git a/libs/gui/include/gui/BufferQueueConsumer.h b/libs/gui/include/gui/BufferQueueConsumer.h
index aa13c0cf13..7db69eca9d 100644
--- a/libs/gui/include/gui/BufferQueueConsumer.h
+++ b/libs/gui/include/gui/BufferQueueConsumer.h
@@ -171,6 +171,9 @@ public:
 
     // End functions required for backwards compatibility
 
+    // Value used to determine if present time is valid.
+    constexpr static int MAX_REASONABLE_NSEC = 1'000'000'000ULL; // 1 second
+
 private:
     sp<BufferQueueCore> mCore;
 
diff --git a/services/surfaceflinger/BufferLayer.cpp b/services/surfaceflinger/BufferLayer.cpp
index 4ea587dbba..06caf1e2dc 100644
--- a/services/surfaceflinger/BufferLayer.cpp
+++ b/services/surfaceflinger/BufferLayer.cpp
@@ -534,11 +534,13 @@ bool BufferLayer::latchBuffer(bool& recomputeVisibleRegions, nsecs_t latchTime)
 
 // transaction
 void BufferLayer::notifyAvailableFrames() {
-    auto headFrameNumber = getHeadFrameNumber();
-    bool headFenceSignaled = fenceHasSignaled();
+    const auto headFrameNumber = getHeadFrameNumber();
+    const bool headFenceSignaled = fenceHasSignaled();
+    const bool presentTimeIsCurrent = framePresentTimeIsCurrent();
     Mutex::Autolock lock(mLocalSyncPointMutex);
     for (auto& point : mLocalSyncPoints) {
-        if (headFrameNumber >= point->getFrameNumber() && headFenceSignaled) {
+        if (headFrameNumber >= point->getFrameNumber() && headFenceSignaled &&
+            presentTimeIsCurrent) {
             point->setFrameAvailable();
         }
     }
diff --git a/services/surfaceflinger/BufferLayer.h b/services/surfaceflinger/BufferLayer.h
index dc103cbada..b679380b79 100644
--- a/services/surfaceflinger/BufferLayer.h
+++ b/services/surfaceflinger/BufferLayer.h
@@ -114,6 +114,7 @@ public:
     // -----------------------------------------------------------------------
 private:
     virtual bool fenceHasSignaled() const = 0;
+    virtual bool framePresentTimeIsCurrent() const = 0;
 
     virtual nsecs_t getDesiredPresentTime() = 0;
     virtual std::shared_ptr<FenceTime> getCurrentFenceTime() const = 0;
diff --git a/services/surfaceflinger/BufferQueueLayer.cpp b/services/surfaceflinger/BufferQueueLayer.cpp
index ff5f271960..5d729f5b4f 100644
--- a/services/surfaceflinger/BufferQueueLayer.cpp
+++ b/services/surfaceflinger/BufferQueueLayer.cpp
@@ -19,6 +19,7 @@
 #include <compositionengine/OutputLayer.h>
 #include <compositionengine/impl/LayerCompositionState.h>
 #include <compositionengine/impl/OutputLayerCompositionState.h>
+#include <gui/BufferQueueConsumer.h>
 #include <system/window.h>
 
 #include "BufferQueueLayer.h"
@@ -133,6 +134,15 @@ bool BufferQueueLayer::fenceHasSignaled() const {
     return mQueueItems[0].mFenceTime->getSignalTime() != Fence::SIGNAL_TIME_PENDING;
 }
 
+bool BufferQueueLayer::framePresentTimeIsCurrent() const {
+    if (!hasFrameUpdate() || isRemovedFromCurrentState()) {
+        return true;
+    }
+
+    Mutex::Autolock lock(mQueueItemLock);
+    return mQueueItems[0].mTimestamp <= mFlinger->mScheduler->expectedPresentTime();
+}
+
 nsecs_t BufferQueueLayer::getDesiredPresentTime() {
     return mConsumer->getTimestamp();
 }
@@ -185,7 +195,37 @@ PixelFormat BufferQueueLayer::getPixelFormat() const {
 
 uint64_t BufferQueueLayer::getFrameNumber() const {
     Mutex::Autolock lock(mQueueItemLock);
-    return mQueueItems[0].mFrameNumber;
+    uint64_t frameNumber = mQueueItems[0].mFrameNumber;
+
+    // The head of the queue will be dropped if there are signaled and timely frames behind it
+    nsecs_t expectedPresentTime = mFlinger->mScheduler->expectedPresentTime();
+
+    if (isRemovedFromCurrentState()) {
+        expectedPresentTime = 0;
+    }
+
+    for (int i = 1; i < mQueueItems.size(); i++) {
+        const bool fenceSignaled =
+                mQueueItems[i].mFenceTime->getSignalTime() != Fence::SIGNAL_TIME_PENDING;
+        if (!fenceSignaled) {
+            break;
+        }
+
+        // We don't drop frames without explicit timestamps
+        if (mQueueItems[i].mIsAutoTimestamp) {
+            break;
+        }
+
+        const nsecs_t desiredPresent = mQueueItems[i].mTimestamp;
+        if (desiredPresent < expectedPresentTime - BufferQueueConsumer::MAX_REASONABLE_NSEC ||
+            desiredPresent > expectedPresentTime) {
+            break;
+        }
+
+        frameNumber = mQueueItems[i].mFrameNumber;
+    }
+
+    return frameNumber;
 }
 
 bool BufferQueueLayer::getAutoRefresh() const {
diff --git a/services/surfaceflinger/BufferQueueLayer.h b/services/surfaceflinger/BufferQueueLayer.h
index a2aad17497..7def33ad78 100644
--- a/services/surfaceflinger/BufferQueueLayer.h
+++ b/services/surfaceflinger/BufferQueueLayer.h
@@ -61,6 +61,7 @@ public:
     // -----------------------------------------------------------------------
 public:
     bool fenceHasSignaled() const override;
+    bool framePresentTimeIsCurrent() const override;
 
 private:
     nsecs_t getDesiredPresentTime() override;
diff --git a/services/surfaceflinger/BufferStateLayer.cpp b/services/surfaceflinger/BufferStateLayer.cpp
index dabc683aa9..30848d6eb5 100644
--- a/services/surfaceflinger/BufferStateLayer.cpp
+++ b/services/surfaceflinger/BufferStateLayer.cpp
@@ -374,6 +374,14 @@ bool BufferStateLayer::fenceHasSignaled() const {
     return getDrawingState().acquireFence->getStatus() == Fence::Status::Signaled;
 }
 
+bool BufferStateLayer::framePresentTimeIsCurrent() const {
+    if (!hasFrameUpdate() || isRemovedFromCurrentState()) {
+        return true;
+    }
+
+    return mDesiredPresentTime <= mFlinger->mScheduler->expectedPresentTime();
+}
+
 nsecs_t BufferStateLayer::getDesiredPresentTime() {
     return mDesiredPresentTime;
 }
diff --git a/services/surfaceflinger/BufferStateLayer.h b/services/surfaceflinger/BufferStateLayer.h
index 13186dd343..4e2bc45287 100644
--- a/services/surfaceflinger/BufferStateLayer.h
+++ b/services/surfaceflinger/BufferStateLayer.h
@@ -101,6 +101,7 @@ public:
     // Interface implementation for BufferLayer
     // -----------------------------------------------------------------------
     bool fenceHasSignaled() const override;
+    bool framePresentTimeIsCurrent() const override;
 
 private:
     nsecs_t getDesiredPresentTime() override;