Merge "Omit DISPLAY_DECORATION layers from CachedSets"
diff --git a/services/surfaceflinger/CompositionEngine/src/planner/Flattener.cpp b/services/surfaceflinger/CompositionEngine/src/planner/Flattener.cpp
index 0918510..8d26747 100644
--- a/services/surfaceflinger/CompositionEngine/src/planner/Flattener.cpp
+++ b/services/surfaceflinger/CompositionEngine/src/planner/Flattener.cpp
@@ -401,6 +401,19 @@
     return true;
 }
 
+namespace {
+bool isDisplayDecoration(const CachedSet& cachedSet) {
+    return cachedSet.getLayerCount() == 1 &&
+            cachedSet.getFirstLayer()
+                    .getState()
+                    ->getOutputLayer()
+                    ->getLayerFE()
+                    .getCompositionState()
+                    ->compositionType ==
+            aidl::android::hardware::graphics::composer3::Composition::DISPLAY_DECORATION;
+}
+} // namespace
+
 std::vector<Flattener::Run> Flattener::findCandidateRuns(time_point now) const {
     ATRACE_CALL();
     std::vector<Run> runs;
@@ -424,7 +437,7 @@
         }
 
         if (layerIsInactive && (firstLayer || runHasFirstLayer || !layerHasBlur) &&
-            !currentSet->hasUnsupportedDataspace()) {
+            !currentSet->hasUnsupportedDataspace() && !isDisplayDecoration(*currentSet)) {
             if (isPartOfRun) {
                 builder.increment();
             } else {
diff --git a/services/surfaceflinger/CompositionEngine/tests/planner/FlattenerTest.cpp b/services/surfaceflinger/CompositionEngine/tests/planner/FlattenerTest.cpp
index 58dc244..656ef9a 100644
--- a/services/surfaceflinger/CompositionEngine/tests/planner/FlattenerTest.cpp
+++ b/services/surfaceflinger/CompositionEngine/tests/planner/FlattenerTest.cpp
@@ -1337,5 +1337,56 @@
     EXPECT_NE(nullptr, overrideBuffer4);
 }
 
+TEST_F(FlattenerTest, flattenLayers_skips_DISPLAY_DECORATION) {
+    auto& layerState1 = mTestLayers[0]->layerState;
+    const auto& overrideBuffer1 = layerState1->getOutputLayer()->getState().overrideInfo.buffer;
+
+    auto& layerState2 = mTestLayers[1]->layerState;
+    const auto& overrideBuffer2 = layerState2->getOutputLayer()->getState().overrideInfo.buffer;
+
+    // The third layer uses DISPLAY_DECORATION, which should never be cached.
+    auto& layerState3 = mTestLayers[2]->layerState;
+    const auto& overrideBuffer3 = layerState3->getOutputLayer()->getState().overrideInfo.buffer;
+    mTestLayers[2]->layerFECompositionState.compositionType =
+            aidl::android::hardware::graphics::composer3::Composition::DISPLAY_DECORATION;
+    mTestLayers[2]->layerState->update(&mTestLayers[2]->outputLayer);
+
+    const std::vector<const LayerState*> layers = {
+            layerState1.get(),
+            layerState2.get(),
+            layerState3.get(),
+    };
+
+    initializeFlattener(layers);
+
+    mTime += 200ms;
+    initializeOverrideBuffer(layers);
+    EXPECT_EQ(getNonBufferHash(layers),
+              mFlattener->flattenLayers(layers, getNonBufferHash(layers), mTime));
+
+    // This will render a CachedSet.
+    EXPECT_CALL(mRenderEngine, drawLayers(_, _, _, _, _))
+            .WillOnce(Return(ByMove(
+                    futureOf<renderengine::RenderEngineResult>({NO_ERROR, base::unique_fd()}))));
+    mFlattener->renderCachedSets(mOutputState, std::nullopt);
+
+    // We've rendered a CachedSet, but we haven't merged it in.
+    EXPECT_EQ(nullptr, overrideBuffer1);
+    EXPECT_EQ(nullptr, overrideBuffer2);
+    EXPECT_EQ(nullptr, overrideBuffer3);
+
+    // This time we merge the CachedSet in, so we have a new hash, and we should
+    // only have two sets.
+    EXPECT_CALL(mRenderEngine, drawLayers(_, _, _, _, _)).Times(0);
+    initializeOverrideBuffer(layers);
+    EXPECT_NE(getNonBufferHash(layers),
+              mFlattener->flattenLayers(layers, getNonBufferHash(layers), mTime));
+    mFlattener->renderCachedSets(mOutputState, std::nullopt);
+
+    EXPECT_NE(nullptr, overrideBuffer1);
+    EXPECT_EQ(overrideBuffer1, overrideBuffer2);
+    EXPECT_EQ(nullptr, overrideBuffer3);
+}
+
 } // namespace
 } // namespace android::compositionengine