7 files changed, 28 insertions, 27 deletions

diff --git a/services/surfaceflinger/BufferLayer.cpp b/services/surfaceflinger/BufferLayer.cpp
index 13c748f24c..e9af9e292b 100644
--- a/services/surfaceflinger/BufferLayer.cpp
+++ b/services/surfaceflinger/BufferLayer.cpp
@@ -668,6 +668,15 @@ FloatRect BufferLayer::computeSourceBounds(const FloatRect& parentBounds) const
     return FloatRect(0, 0, bufWidth, bufHeight);
 }
 
+void BufferLayer::latchAndReleaseBuffer() {
+    mRefreshPending = false;
+    if (hasReadyFrame()) {
+        bool ignored = false;
+        latchBuffer(ignored, systemTime(), 0 /* expectedPresentTime */);
+    }
+    releasePendingBuffer(systemTime());
+}
+
 } // namespace android
 
 #if defined(__gl_h_)
diff --git a/services/surfaceflinger/BufferLayer.h b/services/surfaceflinger/BufferLayer.h
index 7a0f82b5c0..fb8d7d027f 100644
--- a/services/surfaceflinger/BufferLayer.h
+++ b/services/surfaceflinger/BufferLayer.h
@@ -103,6 +103,13 @@ public:
     // Returns the current scaling mode, unless mOverrideScalingMode
     // is set, in which case, it returns mOverrideScalingMode
     uint32_t getEffectiveScalingMode() const override;
+
+    // Calls latchBuffer if the buffer has a frame queued and then releases the buffer.
+    // This is used if the buffer is just latched and releases to free up the buffer
+    // and will not be shown on screen.
+    // Should only be called on the main thread.
+    void latchAndReleaseBuffer() override;
+
     // -----------------------------------------------------------------------
 
     // -----------------------------------------------------------------------
diff --git a/services/surfaceflinger/BufferQueueLayer.cpp b/services/surfaceflinger/BufferQueueLayer.cpp
index 12be00f116..5f494ff3d5 100644
--- a/services/surfaceflinger/BufferQueueLayer.cpp
+++ b/services/surfaceflinger/BufferQueueLayer.cpp
@@ -412,14 +412,6 @@ void BufferQueueLayer::latchPerFrameState(
 // Interface implementation for BufferLayerConsumer::ContentsChangedListener
 // -----------------------------------------------------------------------
 
-void BufferQueueLayer::fakeVsync() {
-    mRefreshPending = false;
-    bool ignored = false;
-    latchBuffer(ignored, systemTime(), 0 /* expectedPresentTime */);
-    usleep(16000);
-    releasePendingBuffer(systemTime());
-}
-
 void BufferQueueLayer::onFrameAvailable(const BufferItem& item) {
     ATRACE_CALL();
     // Add this buffer from our internal queue tracker
@@ -456,13 +448,7 @@ void BufferQueueLayer::onFrameAvailable(const BufferItem& item) {
     mFlinger->mInterceptor->saveBufferUpdate(this, item.mGraphicBuffer->getWidth(),
                                              item.mGraphicBuffer->getHeight(), item.mFrameNumber);
 
-    // If this layer is orphaned, then we run a fake vsync pulse so that
-    // dequeueBuffer doesn't block indefinitely.
-    if (isRemovedFromCurrentState()) {
-        fakeVsync();
-    } else {
-        mFlinger->signalLayerUpdate();
-    }
+    mFlinger->signalLayerUpdate();
     mConsumer->onBufferAvailable(item);
 }
 
diff --git a/services/surfaceflinger/BufferQueueLayer.h b/services/surfaceflinger/BufferQueueLayer.h
index 231a531f58..392b706416 100644
--- a/services/surfaceflinger/BufferQueueLayer.h
+++ b/services/surfaceflinger/BufferQueueLayer.h
@@ -138,8 +138,6 @@ private:
     // thread-safe
     std::atomic<int32_t> mQueuedFrames{0};
     std::atomic<bool> mSidebandStreamChanged{false};
-
-    void fakeVsync();
 };
 
 } // namespace android
diff --git a/services/surfaceflinger/Layer.h b/services/surfaceflinger/Layer.h
index 87a5896c6a..2a1564a440 100644
--- a/services/surfaceflinger/Layer.h
+++ b/services/surfaceflinger/Layer.h
@@ -544,6 +544,8 @@ public:
 
     virtual bool isBufferLatched() const { return false; }
 
+    virtual void latchAndReleaseBuffer() {}
+
     /*
      * Remove relative z for the layer if its relative parent is not part of the
      * provided layer tree.
diff --git a/services/surfaceflinger/SurfaceFlinger.cpp b/services/surfaceflinger/SurfaceFlinger.cpp
index 16b19e8350..7a8eb6b2da 100644
--- a/services/surfaceflinger/SurfaceFlinger.cpp
+++ b/services/surfaceflinger/SurfaceFlinger.cpp
@@ -2870,14 +2870,6 @@ void SurfaceFlinger::updateCursorAsync()
     }
 }
 
-void SurfaceFlinger::latchAndReleaseBuffer(const sp<Layer>& layer) {
-    if (layer->hasReadyFrame()) {
-        bool ignored = false;
-        layer->latchBuffer(ignored, systemTime(), 0 /* expectedPresentTime */);
-    }
-    layer->releasePendingBuffer(systemTime());
-}
-
 void SurfaceFlinger::commitTransaction()
 {
     if (!mLayersPendingRemoval.isEmpty()) {
@@ -2888,7 +2880,7 @@ void SurfaceFlinger::commitTransaction()
 
             // Ensure any buffers set to display on any children are released.
             if (l->isRemovedFromCurrentState()) {
-                latchAndReleaseBuffer(l);
+                l->latchAndReleaseBuffer();
             }
 
             // If the layer has been removed and has no parent, then it will not be reachable
@@ -3146,6 +3138,14 @@ bool SurfaceFlinger::handlePageFlip()
         }
     });
 
+    // The client can continue submitting buffers for offscreen layers, but they will not
+    // be shown on screen. Therefore, we need to latch and release buffers of offscreen
+    // layers to ensure dequeueBuffer doesn't block indefinitely.
+    for (Layer* offscreenLayer : mOffscreenLayers) {
+        offscreenLayer->traverseInZOrder(LayerVector::StateSet::Drawing,
+                                         [&](Layer* l) { l->latchAndReleaseBuffer(); });
+    }
+
     if (!mLayersWithQueuedFrames.empty()) {
         // mStateLock is needed for latchBuffer as LayerRejecter::reject()
         // writes to Layer current state. See also b/119481871
diff --git a/services/surfaceflinger/SurfaceFlinger.h b/services/surfaceflinger/SurfaceFlinger.h
index e199ad55f8..27a0f6bbaf 100644
--- a/services/surfaceflinger/SurfaceFlinger.h
+++ b/services/surfaceflinger/SurfaceFlinger.h
@@ -576,7 +576,6 @@ private:
     // Can only be called from the main thread or with mStateLock held
     uint32_t setTransactionFlags(uint32_t flags);
     uint32_t setTransactionFlags(uint32_t flags, Scheduler::TransactionStart transactionStart);
-    void latchAndReleaseBuffer(const sp<Layer>& layer);
     void commitTransaction() REQUIRES(mStateLock);
     void commitOffscreenLayers();
     bool transactionIsReadyToBeApplied(int64_t desiredPresentTime,