diff --git a/services/surfaceflinger/Android.bp b/services/surfaceflinger/Android.bp
index f1457bf..a8ba15f 100644
--- a/services/surfaceflinger/Android.bp
+++ b/services/surfaceflinger/Android.bp
@@ -163,6 +163,7 @@
         "FrameTracer/FrameTracer.cpp",
         "FrameTracker.cpp",
         "HdrLayerInfoReporter.cpp",
+        "HwcSlotGenerator.cpp",
         "WindowInfosListenerInvoker.cpp",
         "Layer.cpp",
         "LayerProtoHelper.cpp",
diff --git a/services/surfaceflinger/BufferStateLayer.cpp b/services/surfaceflinger/BufferStateLayer.cpp
index 59e2d18..5656e05 100644
--- a/services/surfaceflinger/BufferStateLayer.cpp
+++ b/services/surfaceflinger/BufferStateLayer.cpp
@@ -25,7 +25,6 @@
 
 #include <FrameTimeline/FrameTimeline.h>
 #include <compositionengine/CompositionEngine.h>
-#include <compositionengine/LayerFECompositionState.h>
 #include <gui/BufferQueue.h>
 #include <private/gui/SyncFeatures.h>
 #include <renderengine/Image.h>
@@ -71,22 +70,64 @@
 
 using PresentState = frametimeline::SurfaceFrame::PresentState;
 using gui::WindowInfo;
-void BufferStateLayer::callReleaseBufferCallback(const sp<ITransactionCompletedListener>& listener,
-                                                 const sp<GraphicBuffer>& buffer,
-                                                 uint64_t framenumber,
-                                                 const sp<Fence>& releaseFence,
-                                                 uint32_t currentMaxAcquiredBufferCount) {
-    if (!listener) {
-        return;
-    }
-    ATRACE_FORMAT_INSTANT("callReleaseBufferCallback %s - %" PRIu64, getDebugName(), framenumber);
-    listener->onReleaseBuffer({buffer->getId(), framenumber},
-                              releaseFence ? releaseFence : Fence::NO_FENCE,
-                              currentMaxAcquiredBufferCount);
-}
-
 namespace {
 static constexpr float defaultMaxLuminance = 1000.0;
+
+constexpr mat4 inverseOrientation(uint32_t transform) {
+    const mat4 flipH(-1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 1, 0, 0, 1);
+    const mat4 flipV(1, 0, 0, 0, 0, -1, 0, 0, 0, 0, 1, 0, 0, 1, 0, 1);
+    const mat4 rot90(0, 1, 0, 0, -1, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 1);
+    mat4 tr;
+
+    if (transform & NATIVE_WINDOW_TRANSFORM_ROT_90) {
+        tr = tr * rot90;
+    }
+    if (transform & NATIVE_WINDOW_TRANSFORM_FLIP_H) {
+        tr = tr * flipH;
+    }
+    if (transform & NATIVE_WINDOW_TRANSFORM_FLIP_V) {
+        tr = tr * flipV;
+    }
+    return inverse(tr);
+}
+
+bool assignTransform(ui::Transform* dst, ui::Transform& from) {
+    if (*dst == from) {
+        return false;
+    }
+    *dst = from;
+    return true;
+}
+
+TimeStats::SetFrameRateVote frameRateToSetFrameRateVotePayload(Layer::FrameRate frameRate) {
+    using FrameRateCompatibility = TimeStats::SetFrameRateVote::FrameRateCompatibility;
+    using Seamlessness = TimeStats::SetFrameRateVote::Seamlessness;
+    const auto frameRateCompatibility = [frameRate] {
+        switch (frameRate.type) {
+            case Layer::FrameRateCompatibility::Default:
+                return FrameRateCompatibility::Default;
+            case Layer::FrameRateCompatibility::ExactOrMultiple:
+                return FrameRateCompatibility::ExactOrMultiple;
+            default:
+                return FrameRateCompatibility::Undefined;
+        }
+    }();
+
+    const auto seamlessness = [frameRate] {
+        switch (frameRate.seamlessness) {
+            case scheduler::Seamlessness::OnlySeamless:
+                return Seamlessness::ShouldBeSeamless;
+            case scheduler::Seamlessness::SeamedAndSeamless:
+                return Seamlessness::NotRequired;
+            default:
+                return Seamlessness::Undefined;
+        }
+    }();
+
+    return TimeStats::SetFrameRateVote{.frameRate = frameRate.rate.getValue(),
+                                       .frameRateCompatibility = frameRateCompatibility,
+                                       .seamlessness = seamlessness};
+}
 } // namespace
 
 BufferStateLayer::BufferStateLayer(const LayerCreationArgs& args)
@@ -97,7 +138,6 @@
     ALOGV("Creating Layer %s", getDebugName());
 
     mPremultipliedAlpha = !(args.flags & ISurfaceComposerClient::eNonPremultiplied);
-
     mPotentialCursor = args.flags & ISurfaceComposerClient::eCursorWindow;
     mProtectedByApp = args.flags & ISurfaceComposerClient::eProtectedByApp;
     mDrawingState.dataspace = ui::Dataspace::V0_SRGB;
@@ -127,6 +167,20 @@
     mFlinger->mFrameTracer->onDestroy(layerId);
 }
 
+void BufferStateLayer::callReleaseBufferCallback(const sp<ITransactionCompletedListener>& listener,
+                                                 const sp<GraphicBuffer>& buffer,
+                                                 uint64_t framenumber,
+                                                 const sp<Fence>& releaseFence,
+                                                 uint32_t currentMaxAcquiredBufferCount) {
+    if (!listener) {
+        return;
+    }
+    ATRACE_FORMAT_INSTANT("callReleaseBufferCallback %s - %" PRIu64, getDebugName(), framenumber);
+    listener->onReleaseBuffer({buffer->getId(), framenumber},
+                              releaseFence ? releaseFence : Fence::NO_FENCE,
+                              currentMaxAcquiredBufferCount);
+}
+
 // -----------------------------------------------------------------------
 // Interface implementation for Layer
 // -----------------------------------------------------------------------
@@ -239,14 +293,6 @@
     mDrawingState.callbackHandles = {};
 }
 
-void BufferStateLayer::finalizeFrameEventHistory(const std::shared_ptr<FenceTime>& glDoneFence,
-                                                 const CompositorTiming& compositorTiming) {
-    for (const auto& handle : mDrawingState.callbackHandles) {
-        handle->gpuCompositionDoneFence = glDoneFence;
-        handle->compositorTiming = compositorTiming;
-    }
-}
-
 bool BufferStateLayer::willPresentCurrentTransaction() const {
     // Returns true if the most recent Transaction applied to CurrentState will be presented.
     return (getSidebandStreamChanged() || getAutoRefresh() ||
@@ -307,14 +353,6 @@
     return true;
 }
 
-static bool assignTransform(ui::Transform* dst, ui::Transform& from) {
-    if (*dst == from) {
-        return false;
-    }
-    *dst = from;
-    return true;
-}
-
 // Translate destination frame into scale and position. If a destination frame is not set, use the
 // provided scale and position
 bool BufferStateLayer::updateGeometry() {
@@ -641,14 +679,6 @@
     return fenceSignaled;
 }
 
-bool BufferStateLayer::framePresentTimeIsCurrent(nsecs_t expectedPresentTime) const {
-    if (!hasFrameUpdate() || isRemovedFromCurrentState()) {
-        return true;
-    }
-
-    return mDrawingState.isAutoTimestamp || mDrawingState.desiredPresentTime <= expectedPresentTime;
-}
-
 bool BufferStateLayer::onPreComposition(nsecs_t refreshStartTime) {
     for (const auto& handle : mDrawingState.callbackHandles) {
         handle->refreshStartTime = refreshStartTime;
@@ -685,8 +715,7 @@
     return (mDrawingStateModified || mDrawingState.modified) && (c.buffer != nullptr || c.bgColorLayer != nullptr);
 }
 
-status_t BufferStateLayer::updateTexImage(bool& /*recomputeVisibleRegions*/, nsecs_t latchTime,
-                                          nsecs_t /*expectedPresentTime*/) {
+void BufferStateLayer::updateTexImage(nsecs_t latchTime) {
     const State& s(getDrawingState());
 
     if (!s.buffer) {
@@ -695,7 +724,7 @@
                 handle->latchTime = latchTime;
             }
         }
-        return NO_ERROR;
+        return;
     }
 
     for (auto& handle : mDrawingState.callbackHandles) {
@@ -734,135 +763,36 @@
     mDrawingState.callbackHandles = remainingHandles;
 
     mDrawingStateModified = false;
-
-    return NO_ERROR;
 }
 
-status_t BufferStateLayer::updateActiveBuffer() {
-    const State& s(getDrawingState());
-
-    if (s.buffer == nullptr) {
-        return BAD_VALUE;
-    }
-
-    if (!mBufferInfo.mBuffer || !s.buffer->hasSameBuffer(*mBufferInfo.mBuffer)) {
+void BufferStateLayer::gatherBufferInfo() {
+    if (!mBufferInfo.mBuffer || !mDrawingState.buffer->hasSameBuffer(*mBufferInfo.mBuffer)) {
         decrementPendingBufferCount();
     }
 
     mPreviousReleaseCallbackId = {getCurrentBufferId(), mBufferInfo.mFrameNumber};
-    mBufferInfo.mBuffer = s.buffer;
-    mBufferInfo.mFence = s.acquireFence;
-    mBufferInfo.mFrameNumber = s.frameNumber;
-
-    return NO_ERROR;
-}
-
-status_t BufferStateLayer::updateFrameNumber() {
-    // TODO(marissaw): support frame history events
-    mPreviousFrameNumber = mCurrentFrameNumber;
-    mCurrentFrameNumber = mDrawingState.frameNumber;
-    return NO_ERROR;
-}
-
-void BufferStateLayer::HwcSlotGenerator::bufferErased(const client_cache_t& clientCacheId) {
-    std::lock_guard lock(mMutex);
-    if (!clientCacheId.isValid()) {
-        ALOGE("invalid process, failed to erase buffer");
-        return;
-    }
-    eraseBufferLocked(clientCacheId);
-}
-
-int BufferStateLayer::HwcSlotGenerator::getHwcCacheSlot(const client_cache_t& clientCacheId) {
-    std::lock_guard<std::mutex> lock(mMutex);
-    auto itr = mCachedBuffers.find(clientCacheId);
-    if (itr == mCachedBuffers.end()) {
-        return addCachedBuffer(clientCacheId);
-    }
-    auto& [hwcCacheSlot, counter] = itr->second;
-    counter = mCounter++;
-    return hwcCacheSlot;
-}
-
-int BufferStateLayer::HwcSlotGenerator::addCachedBuffer(const client_cache_t& clientCacheId)
-        REQUIRES(mMutex) {
-    if (!clientCacheId.isValid()) {
-        ALOGE("invalid process, returning invalid slot");
-        return BufferQueue::INVALID_BUFFER_SLOT;
-    }
-
-    ClientCache::getInstance().registerErasedRecipient(clientCacheId, wp<ErasedRecipient>(this));
-
-    int hwcCacheSlot = getFreeHwcCacheSlot();
-    mCachedBuffers[clientCacheId] = {hwcCacheSlot, mCounter++};
-    return hwcCacheSlot;
-}
-
-int BufferStateLayer::HwcSlotGenerator::getFreeHwcCacheSlot() REQUIRES(mMutex) {
-    if (mFreeHwcCacheSlots.empty()) {
-        evictLeastRecentlyUsed();
-    }
-
-    int hwcCacheSlot = mFreeHwcCacheSlots.top();
-    mFreeHwcCacheSlots.pop();
-    return hwcCacheSlot;
-}
-
-void BufferStateLayer::HwcSlotGenerator::evictLeastRecentlyUsed() REQUIRES(mMutex) {
-    uint64_t minCounter = UINT_MAX;
-    client_cache_t minClientCacheId = {};
-    for (const auto& [clientCacheId, slotCounter] : mCachedBuffers) {
-        const auto& [hwcCacheSlot, counter] = slotCounter;
-        if (counter < minCounter) {
-            minCounter = counter;
-            minClientCacheId = clientCacheId;
-        }
-    }
-    eraseBufferLocked(minClientCacheId);
-
-    ClientCache::getInstance().unregisterErasedRecipient(minClientCacheId, this);
-}
-
-void BufferStateLayer::HwcSlotGenerator::eraseBufferLocked(const client_cache_t& clientCacheId)
-        REQUIRES(mMutex) {
-    auto itr = mCachedBuffers.find(clientCacheId);
-    if (itr == mCachedBuffers.end()) {
-        return;
-    }
-    auto& [hwcCacheSlot, counter] = itr->second;
-
-    // TODO send to hwc cache and resources
-
-    mFreeHwcCacheSlots.push(hwcCacheSlot);
-    mCachedBuffers.erase(clientCacheId);
-}
-
-void BufferStateLayer::gatherBufferInfo() {
+    mBufferInfo.mBuffer = mDrawingState.buffer;
+    mBufferInfo.mFence = mDrawingState.acquireFence;
+    mBufferInfo.mFrameNumber = mDrawingState.frameNumber;
     mBufferInfo.mPixelFormat =
             !mBufferInfo.mBuffer ? PIXEL_FORMAT_NONE : mBufferInfo.mBuffer->getPixelFormat();
     mBufferInfo.mFrameLatencyNeeded = true;
-
-    const State& s(getDrawingState());
-    mBufferInfo.mDesiredPresentTime = s.desiredPresentTime;
-    mBufferInfo.mFenceTime = std::make_shared<FenceTime>(s.acquireFence);
-    mBufferInfo.mFence = s.acquireFence;
-    mBufferInfo.mTransform = s.bufferTransform;
+    mBufferInfo.mDesiredPresentTime = mDrawingState.desiredPresentTime;
+    mBufferInfo.mFenceTime = std::make_shared<FenceTime>(mDrawingState.acquireFence);
+    mBufferInfo.mFence = mDrawingState.acquireFence;
+    mBufferInfo.mTransform = mDrawingState.bufferTransform;
     auto lastDataspace = mBufferInfo.mDataspace;
-    mBufferInfo.mDataspace = translateDataspace(s.dataspace);
+    mBufferInfo.mDataspace = translateDataspace(mDrawingState.dataspace);
     if (lastDataspace != mBufferInfo.mDataspace) {
         mFlinger->mSomeDataspaceChanged = true;
     }
-    mBufferInfo.mCrop = computeBufferCrop(s);
+    mBufferInfo.mCrop = computeBufferCrop(mDrawingState);
     mBufferInfo.mScaleMode = NATIVE_WINDOW_SCALING_MODE_SCALE_TO_WINDOW;
-    mBufferInfo.mSurfaceDamage = s.surfaceDamageRegion;
-    mBufferInfo.mHdrMetadata = s.hdrMetadata;
-    mBufferInfo.mApi = s.api;
-    mBufferInfo.mTransformToDisplayInverse = s.transformToDisplayInverse;
-    mBufferInfo.mBufferSlot = mHwcSlotGenerator->getHwcCacheSlot(s.clientCacheId);
-}
-
-uint32_t BufferStateLayer::getEffectiveScalingMode() const {
-   return NATIVE_WINDOW_SCALING_MODE_SCALE_TO_WINDOW;
+    mBufferInfo.mSurfaceDamage = mDrawingState.surfaceDamageRegion;
+    mBufferInfo.mHdrMetadata = mDrawingState.hdrMetadata;
+    mBufferInfo.mApi = mDrawingState.api;
+    mBufferInfo.mTransformToDisplayInverse = mDrawingState.transformToDisplayInverse;
+    mBufferInfo.mBufferSlot = mHwcSlotGenerator->getHwcCacheSlot(mDrawingState.clientCacheId);
 }
 
 Rect BufferStateLayer::computeBufferCrop(const State& s) {
@@ -1178,32 +1108,6 @@
             (mBufferInfo.mBuffer != nullptr || mSidebandStream != nullptr);
 }
 
-bool BufferStateLayer::isFixedSize() const {
-    return true;
-}
-
-bool BufferStateLayer::usesSourceCrop() const {
-    return true;
-}
-
-static constexpr mat4 inverseOrientation(uint32_t transform) {
-    const mat4 flipH(-1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 1, 0, 0, 1);
-    const mat4 flipV(1, 0, 0, 0, 0, -1, 0, 0, 0, 0, 1, 0, 0, 1, 0, 1);
-    const mat4 rot90(0, 1, 0, 0, -1, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 1);
-    mat4 tr;
-
-    if (transform & NATIVE_WINDOW_TRANSFORM_ROT_90) {
-        tr = tr * rot90;
-    }
-    if (transform & NATIVE_WINDOW_TRANSFORM_FLIP_H) {
-        tr = tr * flipH;
-    }
-    if (transform & NATIVE_WINDOW_TRANSFORM_FLIP_V) {
-        tr = tr * flipV;
-    }
-    return inverse(tr);
-}
-
 std::optional<compositionengine::LayerFE::LayerSettings> BufferStateLayer::prepareClientComposition(
         compositionengine::LayerFE::ClientCompositionTargetSettings& targetSettings) {
     ATRACE_CALL();
@@ -1373,38 +1277,6 @@
     compositionState->sidebandStreamHasFrame = false;
 }
 
-namespace {
-TimeStats::SetFrameRateVote frameRateToSetFrameRateVotePayload(Layer::FrameRate frameRate) {
-    using FrameRateCompatibility = TimeStats::SetFrameRateVote::FrameRateCompatibility;
-    using Seamlessness = TimeStats::SetFrameRateVote::Seamlessness;
-    const auto frameRateCompatibility = [frameRate] {
-        switch (frameRate.type) {
-            case Layer::FrameRateCompatibility::Default:
-                return FrameRateCompatibility::Default;
-            case Layer::FrameRateCompatibility::ExactOrMultiple:
-                return FrameRateCompatibility::ExactOrMultiple;
-            default:
-                return FrameRateCompatibility::Undefined;
-        }
-    }();
-
-    const auto seamlessness = [frameRate] {
-        switch (frameRate.seamlessness) {
-            case scheduler::Seamlessness::OnlySeamless:
-                return Seamlessness::ShouldBeSeamless;
-            case scheduler::Seamlessness::SeamedAndSeamless:
-                return Seamlessness::NotRequired;
-            default:
-                return Seamlessness::Undefined;
-        }
-    }();
-
-    return TimeStats::SetFrameRateVote{.frameRate = frameRate.rate.getValue(),
-                                       .frameRateCompatibility = frameRateCompatibility,
-                                       .seamlessness = seamlessness};
-}
-} // namespace
-
 void BufferStateLayer::onPostComposition(const DisplayDevice* display,
                                          const std::shared_ptr<FenceTime>& glDoneFence,
                                          const std::shared_ptr<FenceTime>& presentFence,
@@ -1413,8 +1285,10 @@
     // composition.
     if (!mBufferInfo.mFrameLatencyNeeded) return;
 
-    // Update mFrameEventHistory.
-    finalizeFrameEventHistory(glDoneFence, compositorTiming);
+    for (const auto& handle : mDrawingState.callbackHandles) {
+        handle->gpuCompositionDoneFence = glDoneFence;
+        handle->compositorTiming = compositorTiming;
+    }
 
     // Update mFrameTracker.
     nsecs_t desiredPresentTime = mBufferInfo.mDesiredPresentTime;
@@ -1480,8 +1354,7 @@
     mBufferInfo.mFrameLatencyNeeded = false;
 }
 
-bool BufferStateLayer::latchBuffer(bool& recomputeVisibleRegions, nsecs_t latchTime,
-                                   nsecs_t expectedPresentTime) {
+bool BufferStateLayer::latchBuffer(bool& recomputeVisibleRegions, nsecs_t latchTime) {
     ATRACE_FORMAT_INSTANT("latchBuffer %s - %" PRIu64, getDebugName(),
                           getDrawingState().frameNumber);
 
@@ -1499,27 +1372,16 @@
         return false;
     }
 
+    updateTexImage(latchTime);
+    if (mDrawingState.buffer == nullptr) {
+        return false;
+    }
+
     // Capture the old state of the layer for comparisons later
-    const State& s(getDrawingState());
-    const bool oldOpacity = isOpaque(s);
-
     BufferInfo oldBufferInfo = mBufferInfo;
-
-    status_t err = updateTexImage(recomputeVisibleRegions, latchTime, expectedPresentTime);
-    if (err != NO_ERROR) {
-        return false;
-    }
-
-    err = updateActiveBuffer();
-    if (err != NO_ERROR) {
-        return false;
-    }
-
-    err = updateFrameNumber();
-    if (err != NO_ERROR) {
-        return false;
-    }
-
+    const bool oldOpacity = isOpaque(mDrawingState);
+    mPreviousFrameNumber = mCurrentFrameNumber;
+    mCurrentFrameNumber = mDrawingState.frameNumber;
     gatherBufferInfo();
 
     if (oldBufferInfo.mBuffer == nullptr) {
@@ -1544,7 +1406,7 @@
         }
     }
 
-    if (oldOpacity != isOpaque(s)) {
+    if (oldOpacity != isOpaque(mDrawingState)) {
         recomputeVisibleRegions = true;
     }
 
@@ -1628,7 +1490,7 @@
 void BufferStateLayer::latchAndReleaseBuffer() {
     if (hasReadyFrame()) {
         bool ignored = false;
-        latchBuffer(ignored, systemTime(), 0 /* expectedPresentTime */);
+        latchBuffer(ignored, systemTime());
     }
     releasePendingBuffer(systemTime());
 }
diff --git a/services/surfaceflinger/BufferStateLayer.h b/services/surfaceflinger/BufferStateLayer.h
index df7ae61..8bad3d2 100644
--- a/services/surfaceflinger/BufferStateLayer.h
+++ b/services/surfaceflinger/BufferStateLayer.h
@@ -40,6 +40,7 @@
 #include "DisplayHardware/HWComposer.h"
 #include "FrameTimeline.h"
 #include "FrameTracker.h"
+#include "HwcSlotGenerator.h"
 #include "Layer.h"
 #include "LayerVector.h"
 #include "SurfaceFlinger.h"
@@ -74,10 +75,7 @@
     // GRALLOC_USAGE_PROTECTED sense.
     bool isProtected() const override;
 
-    // isFixedSize - true if content has a fixed size
-    bool isFixedSize() const override;
-
-    bool usesSourceCrop() const override;
+    bool usesSourceCrop() const override { return true; }
 
     bool isHdrY410() const override;
 
@@ -89,13 +87,9 @@
     // the visible regions need to be recomputed (this is a fairly heavy
     // operation, so this should be set only if needed). Typically this is used
     // to figure out if the content or size of a surface has changed.
-    bool latchBuffer(bool& recomputeVisibleRegions, nsecs_t latchTime,
-                     nsecs_t expectedPresentTime) override;
+    bool latchBuffer(bool& recomputeVisibleRegions, nsecs_t latchTime) override;
     bool hasReadyFrame() const override;
 
-    // Returns the current scaling mode
-    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.
@@ -122,14 +116,6 @@
 
     void releasePendingBuffer(nsecs_t dequeueReadyTime) override;
 
-    void finalizeFrameEventHistory(const std::shared_ptr<FenceTime>& glDoneFence,
-                                   const CompositorTiming& compositorTiming) override;
-
-    // Returns true if the next buffer should be presented at the expected present time,
-    // overridden by BufferStateLayer and BufferQueueLayer for implementation
-    // specific logic
-    bool isBufferDue(nsecs_t /*expectedPresentTime*/) const { return true; }
-
     Region getActiveTransparentRegion(const Layer::State& s) const override {
         return s.transparentRegionHint;
     }
@@ -166,7 +152,6 @@
     bool updateGeometry() override;
 
     bool fenceHasSignaled() const;
-    bool framePresentTimeIsCurrent(nsecs_t expectedPresentTime) const;
     bool onPreComposition(nsecs_t) override;
 
     // See mPendingBufferTransactions
@@ -174,9 +159,6 @@
     std::atomic<int32_t>* getPendingBufferCounter() override { return &mPendingBufferTransactions; }
     std::string getPendingBufferCounterName() override { return mBlastTransactionName; }
 
-    // Returns true if the next buffer should be presented at the expected present time
-    bool shouldPresentNow(nsecs_t /*expectedPresentTime*/) const override { return true; }
-
 protected:
     void gatherBufferInfo();
     void onSurfaceFrameCreated(const std::shared_ptr<frametimeline::SurfaceFrame>& surfaceFrame);
@@ -268,11 +250,7 @@
 
     bool hasFrameUpdate() const;
 
-    status_t updateTexImage(bool& recomputeVisibleRegions, nsecs_t latchTime,
-                            nsecs_t expectedPresentTime);
-
-    status_t updateActiveBuffer();
-    status_t updateFrameNumber();
+    void updateTexImage(nsecs_t latchTime);
 
     sp<Layer> createClone() override;
 
@@ -323,45 +301,6 @@
     // not specify a destination frame.
     ui::Transform mRequestedTransform;
 
-    // TODO(marissaw): support sticky transform for LEGACY camera mode
-
-    class HwcSlotGenerator : public ClientCache::ErasedRecipient {
-    public:
-        HwcSlotGenerator() {
-            for (int i = 0; i < BufferQueue::NUM_BUFFER_SLOTS; i++) {
-                mFreeHwcCacheSlots.push(i);
-            }
-        }
-
-        void bufferErased(const client_cache_t& clientCacheId);
-
-        int getHwcCacheSlot(const client_cache_t& clientCacheId);
-
-    private:
-        friend class SlotGenerationTest;
-        int addCachedBuffer(const client_cache_t& clientCacheId) REQUIRES(mMutex);
-        int getFreeHwcCacheSlot() REQUIRES(mMutex);
-        void evictLeastRecentlyUsed() REQUIRES(mMutex);
-        void eraseBufferLocked(const client_cache_t& clientCacheId) REQUIRES(mMutex);
-
-        struct CachedBufferHash {
-            std::size_t operator()(const client_cache_t& clientCacheId) const {
-                return std::hash<uint64_t>{}(clientCacheId.id);
-            }
-        };
-
-        std::mutex mMutex;
-
-        std::unordered_map<client_cache_t, std::pair<int /*HwcCacheSlot*/, uint64_t /*counter*/>,
-                           CachedBufferHash>
-                mCachedBuffers GUARDED_BY(mMutex);
-        std::stack<int /*HwcCacheSlot*/> mFreeHwcCacheSlots GUARDED_BY(mMutex);
-
-        // The cache increments this counter value when a slot is updated or used.
-        // Used to track the least recently-used buffer
-        uint64_t mCounter = 0;
-    };
-
     sp<HwcSlotGenerator> mHwcSlotGenerator;
 };
 
diff --git a/services/surfaceflinger/HwcSlotGenerator.cpp b/services/surfaceflinger/HwcSlotGenerator.cpp
new file mode 100644
index 0000000..b7e9607
--- /dev/null
+++ b/services/surfaceflinger/HwcSlotGenerator.cpp
@@ -0,0 +1,104 @@
+/*
+ * Copyright 2022 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.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#undef LOG_TAG
+#define LOG_TAG "HwcSlotGenerator"
+#define ATRACE_TAG ATRACE_TAG_GRAPHICS
+
+#include <gui/BufferQueue.h>
+
+#include "HwcSlotGenerator.h"
+
+namespace android {
+
+HwcSlotGenerator::HwcSlotGenerator() {
+    for (int i = 0; i < BufferQueue::NUM_BUFFER_SLOTS; i++) {
+        mFreeHwcCacheSlots.push(i);
+    }
+}
+
+void HwcSlotGenerator::bufferErased(const client_cache_t& clientCacheId) {
+    std::lock_guard lock(mMutex);
+    if (!clientCacheId.isValid()) {
+        ALOGE("invalid process, failed to erase buffer");
+        return;
+    }
+    eraseBufferLocked(clientCacheId);
+}
+
+int HwcSlotGenerator::getHwcCacheSlot(const client_cache_t& clientCacheId) {
+    std::lock_guard<std::mutex> lock(mMutex);
+    auto itr = mCachedBuffers.find(clientCacheId);
+    if (itr == mCachedBuffers.end()) {
+        return addCachedBuffer(clientCacheId);
+    }
+    auto& [hwcCacheSlot, counter] = itr->second;
+    counter = mCounter++;
+    return hwcCacheSlot;
+}
+
+int HwcSlotGenerator::addCachedBuffer(const client_cache_t& clientCacheId) REQUIRES(mMutex) {
+    if (!clientCacheId.isValid()) {
+        ALOGE("invalid process, returning invalid slot");
+        return BufferQueue::INVALID_BUFFER_SLOT;
+    }
+
+    ClientCache::getInstance().registerErasedRecipient(clientCacheId, wp<ErasedRecipient>(this));
+
+    int hwcCacheSlot = getFreeHwcCacheSlot();
+    mCachedBuffers[clientCacheId] = {hwcCacheSlot, mCounter++};
+    return hwcCacheSlot;
+}
+
+int HwcSlotGenerator::getFreeHwcCacheSlot() REQUIRES(mMutex) {
+    if (mFreeHwcCacheSlots.empty()) {
+        evictLeastRecentlyUsed();
+    }
+
+    int hwcCacheSlot = mFreeHwcCacheSlots.top();
+    mFreeHwcCacheSlots.pop();
+    return hwcCacheSlot;
+}
+
+void HwcSlotGenerator::evictLeastRecentlyUsed() REQUIRES(mMutex) {
+    uint64_t minCounter = UINT_MAX;
+    client_cache_t minClientCacheId = {};
+    for (const auto& [clientCacheId, slotCounter] : mCachedBuffers) {
+        const auto& [hwcCacheSlot, counter] = slotCounter;
+        if (counter < minCounter) {
+            minCounter = counter;
+            minClientCacheId = clientCacheId;
+        }
+    }
+    eraseBufferLocked(minClientCacheId);
+
+    ClientCache::getInstance().unregisterErasedRecipient(minClientCacheId, this);
+}
+
+void HwcSlotGenerator::eraseBufferLocked(const client_cache_t& clientCacheId) REQUIRES(mMutex) {
+    auto itr = mCachedBuffers.find(clientCacheId);
+    if (itr == mCachedBuffers.end()) {
+        return;
+    }
+    auto& [hwcCacheSlot, counter] = itr->second;
+
+    // TODO send to hwc cache and resources
+
+    mFreeHwcCacheSlots.push(hwcCacheSlot);
+    mCachedBuffers.erase(clientCacheId);
+}
+
+} // namespace android
diff --git a/services/surfaceflinger/HwcSlotGenerator.h b/services/surfaceflinger/HwcSlotGenerator.h
new file mode 100644
index 0000000..5a1b6d7
--- /dev/null
+++ b/services/surfaceflinger/HwcSlotGenerator.h
@@ -0,0 +1,58 @@
+/*
+ * Copyright 2022 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.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <functional>
+#include <mutex>
+#include <stack>
+#include <unordered_map>
+
+#include "ClientCache.h"
+
+namespace android {
+
+class HwcSlotGenerator : public ClientCache::ErasedRecipient {
+public:
+    HwcSlotGenerator();
+    void bufferErased(const client_cache_t& clientCacheId);
+    int getHwcCacheSlot(const client_cache_t& clientCacheId);
+
+private:
+    friend class SlotGenerationTest;
+    int addCachedBuffer(const client_cache_t& clientCacheId) REQUIRES(mMutex);
+    int getFreeHwcCacheSlot() REQUIRES(mMutex);
+    void evictLeastRecentlyUsed() REQUIRES(mMutex);
+    void eraseBufferLocked(const client_cache_t& clientCacheId) REQUIRES(mMutex);
+
+    struct CachedBufferHash {
+        std::size_t operator()(const client_cache_t& clientCacheId) const {
+            return std::hash<uint64_t>{}(clientCacheId.id);
+        }
+    };
+
+    std::mutex mMutex;
+
+    std::unordered_map<client_cache_t, std::pair<int /*HwcCacheSlot*/, uint64_t /*counter*/>,
+                       CachedBufferHash>
+            mCachedBuffers GUARDED_BY(mMutex);
+    std::stack<int /*HwcCacheSlot*/> mFreeHwcCacheSlots GUARDED_BY(mMutex);
+
+    // The cache increments this counter value when a slot is updated or used.
+    // Used to track the least recently-used buffer
+    uint64_t mCounter = 0;
+};
+} // namespace android
diff --git a/services/surfaceflinger/Layer.cpp b/services/surfaceflinger/Layer.cpp
index ba3cb51..fe12a0b 100644
--- a/services/surfaceflinger/Layer.cpp
+++ b/services/surfaceflinger/Layer.cpp
@@ -2112,8 +2112,6 @@
     layerInfo->set_dataspace(dataspaceDetails(static_cast<android_dataspace>(getDataSpace())));
     layerInfo->set_queued_frames(getQueuedFrameCount());
     layerInfo->set_curr_frame(mCurrentFrameNumber);
-    layerInfo->set_effective_scaling_mode(getEffectiveScalingMode());
-
     layerInfo->set_requested_corner_radius(getDrawingState().cornerRadius);
     layerInfo->set_corner_radius(
             (getRoundedCornerState().radius.x + getRoundedCornerState().radius.y) / 2.0);
diff --git a/services/surfaceflinger/Layer.h b/services/surfaceflinger/Layer.h
index b809c8a..67e4e8f 100644
--- a/services/surfaceflinger/Layer.h
+++ b/services/surfaceflinger/Layer.h
@@ -528,8 +528,6 @@
 
     virtual bool isHdrY410() const { return false; }
 
-    virtual bool shouldPresentNow(nsecs_t /*expectedPresentTime*/) const { return false; }
-
     /*
      * called after composition.
      * returns true if the layer latched a new buffer this frame.
@@ -542,17 +540,13 @@
     // If a buffer was replaced this frame, release the former buffer
     virtual void releasePendingBuffer(nsecs_t /*dequeueReadyTime*/) { }
 
-    virtual void finalizeFrameEventHistory(const std::shared_ptr<FenceTime>& /*glDoneFence*/,
-                                           const CompositorTiming& /*compositorTiming*/) {}
-
     /*
      * latchBuffer - called each time the screen is redrawn and returns whether
      * the visible regions need to be recomputed (this is a fairly heavy
      * operation, so this should be set only if needed). Typically this is used
      * to figure out if the content or size of a surface has changed.
      */
-    virtual bool latchBuffer(bool& /*recomputeVisibleRegions*/, nsecs_t /*latchTime*/,
-                             nsecs_t /*expectedPresentTime*/) {
+    virtual bool latchBuffer(bool& /*recomputeVisibleRegions*/, nsecs_t /*latchTime*/) {
         return false;
     }
 
@@ -926,11 +920,6 @@
     virtual void commitTransaction(State& stateToCommit);
     virtual void onSurfaceFrameCreated(const std::shared_ptr<frametimeline::SurfaceFrame>&) {}
 
-    // Returns mCurrentScaling mode (originating from the
-    // Client) or mOverrideScalingMode mode (originating from
-    // the Surface Controller) if set.
-    virtual uint32_t getEffectiveScalingMode() const { return 0; }
-
     sp<compositionengine::LayerFE> asLayerFE() const;
     sp<Layer> getClonedFrom() { return mClonedFrom != nullptr ? mClonedFrom.promote() : nullptr; }
     bool isClone() { return mClonedFrom != nullptr; }
diff --git a/services/surfaceflinger/SurfaceFlinger.cpp b/services/surfaceflinger/SurfaceFlinger.cpp
index 9ef8e7b..e880bd4 100644
--- a/services/surfaceflinger/SurfaceFlinger.cpp
+++ b/services/surfaceflinger/SurfaceFlinger.cpp
@@ -3540,8 +3540,6 @@
     bool frameQueued = false;
     bool newDataLatched = false;
 
-    const nsecs_t expectedPresentTime = mExpectedPresentTime.load();
-
     // Store the set of layers that need updates. This set must not change as
     // buffers are being latched, as this could result in a deadlock.
     // Example: Two producers share the same command stream and:
@@ -3561,12 +3559,7 @@
 
         if (layer->hasReadyFrame()) {
             frameQueued = true;
-            if (layer->shouldPresentNow(expectedPresentTime)) {
-                mLayersWithQueuedFrames.emplace(layer);
-            } else {
-                ATRACE_NAME("!layer->shouldPresentNow()");
-                layer->useEmptyDamage();
-            }
+            mLayersWithQueuedFrames.emplace(layer);
         } else {
             layer->useEmptyDamage();
         }
@@ -3587,7 +3580,7 @@
         Mutex::Autolock lock(mStateLock);
 
         for (const auto& layer : mLayersWithQueuedFrames) {
-            if (layer->latchBuffer(visibleRegions, latchTime, expectedPresentTime)) {
+            if (layer->latchBuffer(visibleRegions, latchTime)) {
                 mLayersPendingRefresh.push_back(layer);
                 newDataLatched = true;
             }
diff --git a/services/surfaceflinger/fuzzer/surfaceflinger_layer_fuzzer.cpp b/services/surfaceflinger/fuzzer/surfaceflinger_layer_fuzzer.cpp
index 4d90b1e..ed94e76 100644
--- a/services/surfaceflinger/fuzzer/surfaceflinger_layer_fuzzer.cpp
+++ b/services/surfaceflinger/fuzzer/surfaceflinger_layer_fuzzer.cpp
@@ -125,9 +125,7 @@
             ftl::yield<FenceResult>(base::unexpected(mFdp.ConsumeIntegral<status_t>())).share());
 
     layer->releasePendingBuffer(mFdp.ConsumeIntegral<int64_t>());
-    layer->finalizeFrameEventHistory(fenceTime, compositorTiming);
     layer->onPostComposition(nullptr, fenceTime, fenceTime, compositorTiming);
-    layer->isBufferDue(mFdp.ConsumeIntegral<int64_t>());
 
     layer->setTransform(mFdp.ConsumeIntegral<uint32_t>());
     layer->setTransformToDisplayInverse(mFdp.ConsumeBool());
@@ -151,7 +149,6 @@
     layer->computeSourceBounds(getFuzzedFloatRect(&mFdp));
 
     layer->fenceHasSignaled();
-    layer->framePresentTimeIsCurrent(mFdp.ConsumeIntegral<int64_t>());
     layer->onPreComposition(mFdp.ConsumeIntegral<int64_t>());
     const std::vector<sp<CallbackHandle>> callbacks;
     layer->setTransactionCompletedListeners(callbacks);
diff --git a/services/surfaceflinger/tests/unittests/CachingTest.cpp b/services/surfaceflinger/tests/unittests/CachingTest.cpp
index 6f85498..7f203ce 100644
--- a/services/surfaceflinger/tests/unittests/CachingTest.cpp
+++ b/services/surfaceflinger/tests/unittests/CachingTest.cpp
@@ -26,8 +26,7 @@
 
 class SlotGenerationTest : public testing::Test {
 protected:
-    sp<BufferStateLayer::HwcSlotGenerator> mHwcSlotGenerator =
-            sp<BufferStateLayer::HwcSlotGenerator>::make();
+    sp<HwcSlotGenerator> mHwcSlotGenerator = sp<HwcSlotGenerator>::make();
     sp<GraphicBuffer> mBuffer1{new GraphicBuffer(1, 1, HAL_PIXEL_FORMAT_RGBA_8888, 1, 0)};
     sp<GraphicBuffer> mBuffer2{new GraphicBuffer(1, 1, HAL_PIXEL_FORMAT_RGBA_8888, 1, 0)};
     sp<GraphicBuffer> mBuffer3{new GraphicBuffer(10, 10, HAL_PIXEL_FORMAT_RGBA_8888, 1, 0)};
diff --git a/services/surfaceflinger/tests/unittests/CompositionTest.cpp b/services/surfaceflinger/tests/unittests/CompositionTest.cpp
index f6ebfe5..9c16e4c 100644
--- a/services/surfaceflinger/tests/unittests/CompositionTest.cpp
+++ b/services/surfaceflinger/tests/unittests/CompositionTest.cpp
@@ -511,7 +511,7 @@
                 Region(Rect(LayerProperties::HEIGHT, LayerProperties::WIDTH)));
 
         bool ignoredRecomputeVisibleRegions;
-        layer->latchBuffer(ignoredRecomputeVisibleRegions, 0, 0);
+        layer->latchBuffer(ignoredRecomputeVisibleRegions, 0);
         Mock::VerifyAndClear(test->mRenderEngine);
     }
 
diff --git a/services/surfaceflinger/tests/unittests/TransactionFrameTracerTest.cpp b/services/surfaceflinger/tests/unittests/TransactionFrameTracerTest.cpp
index 5364630..28bf8bf 100644
--- a/services/surfaceflinger/tests/unittests/TransactionFrameTracerTest.cpp
+++ b/services/surfaceflinger/tests/unittests/TransactionFrameTracerTest.cpp
@@ -127,7 +127,6 @@
                          dequeueTime, FrameTimelineInfo{});
 
         commitTransaction(layer.get());
-        bool computeVisisbleRegions;
         nsecs_t latchTime = 25;
         EXPECT_CALL(*mFlinger.getFrameTracer(),
                     traceFence(layerId, bufferId, frameNumber, _,
@@ -135,7 +134,7 @@
         EXPECT_CALL(*mFlinger.getFrameTracer(),
                     traceTimestamp(layerId, bufferId, frameNumber, latchTime,
                                    FrameTracer::FrameEvent::LATCH, /*duration*/ 0));
-        layer->updateTexImage(computeVisisbleRegions, latchTime, /*expectedPresentTime*/ 0);
+        layer->updateTexImage(latchTime);
 
         auto glDoneFence = fenceFactory.createFenceTimeForTest(fence);
         auto presentFence = fenceFactory.createFenceTimeForTest(fence);
diff --git a/services/surfaceflinger/tests/unittests/TransactionSurfaceFrameTest.cpp b/services/surfaceflinger/tests/unittests/TransactionSurfaceFrameTest.cpp
index 6d58303..e943644 100644
--- a/services/surfaceflinger/tests/unittests/TransactionSurfaceFrameTest.cpp
+++ b/services/surfaceflinger/tests/unittests/TransactionSurfaceFrameTest.cpp
@@ -140,8 +140,7 @@
         // Buffers are presented only at latch time.
         EXPECT_EQ(PresentState::Unknown, surfaceFrame->getPresentState());
 
-        bool computeVisisbleRegions;
-        layer->updateTexImage(computeVisisbleRegions, 15, 0);
+        layer->updateTexImage(15);
 
         EXPECT_EQ(1, surfaceFrame->getToken());
         EXPECT_EQ(true, surfaceFrame->getIsBuffer());
@@ -192,8 +191,7 @@
         const auto presentedSurfaceFrame = layer->mDrawingState.bufferSurfaceFrameTX;
 
         commitTransaction(layer.get());
-        bool computeVisisbleRegions;
-        layer->updateTexImage(computeVisisbleRegions, 15, 0);
+        layer->updateTexImage(15);
 
         EXPECT_EQ(1, droppedSurfaceFrame->getToken());
         EXPECT_EQ(true, droppedSurfaceFrame->getIsBuffer());
@@ -243,8 +241,7 @@
         // Buffers are presented only at latch time.
         EXPECT_EQ(PresentState::Unknown, surfaceFrame->getPresentState());
 
-        bool computeVisisbleRegions;
-        layer->updateTexImage(computeVisisbleRegions, 15, 0);
+        layer->updateTexImage(15);
 
         EXPECT_EQ(PresentState::Presented, surfaceFrame->getPresentState());
     }
@@ -331,8 +328,7 @@
         // Buffers are presented only at latch time.
         EXPECT_EQ(PresentState::Unknown, bufferSurfaceFrameTX->getPresentState());
 
-        bool computeVisisbleRegions;
-        layer->updateTexImage(computeVisisbleRegions, 15, 0);
+        layer->updateTexImage(15);
 
         EXPECT_EQ(PresentState::Presented, bufferSurfaceFrameTX->getPresentState());
     }
@@ -377,8 +373,7 @@
         auto presentedSurfaceFrame = layer->mDrawingState.bufferSurfaceFrameTX;
 
         commitTransaction(layer.get());
-        bool computeVisisbleRegions;
-        layer->updateTexImage(computeVisisbleRegions, 15, 0);
+        layer->updateTexImage(15);
 
         // Both the droppedSurfaceFrame and presentedSurfaceFrame should be in
         // pendingJankClassifications.
@@ -458,8 +453,7 @@
         const auto presentedSurfaceFrame = layer->mDrawingState.bufferSurfaceFrameTX;
 
         commitTransaction(layer.get());
-        bool computeVisisbleRegions;
-        layer->updateTexImage(computeVisisbleRegions, 15, 0);
+        layer->updateTexImage(15);
 
         EXPECT_EQ(1, droppedSurfaceFrame1->getToken());
         EXPECT_EQ(true, droppedSurfaceFrame1->getIsBuffer());
@@ -517,8 +511,7 @@
         }
 
         auto presentedBufferSurfaceFrame = layer->mDrawingState.bufferSurfaceFrameTX;
-        bool computeVisisbleRegions;
-        layer->updateTexImage(computeVisisbleRegions, 15, 0);
+        layer->updateTexImage(15);
         // BufferlessSurfaceFrames are immediately set to presented and added to the DisplayFrame.
         // Since we don't have access to DisplayFrame here, trigger an onPresent directly.
         for (auto& surfaceFrame : bufferlessSurfaceFrames) {