diff --git a/libs/gui/BufferQueueConsumer.cpp b/libs/gui/BufferQueueConsumer.cpp
index 11f5174..69d25be 100644
--- a/libs/gui/BufferQueueConsumer.cpp
+++ b/libs/gui/BufferQueueConsumer.cpp
@@ -42,6 +42,8 @@
 
 #include <system/window.h>
 
+#include <com_android_graphics_libgui_flags.h>
+
 namespace android {
 
 // Macros for include BufferQueueCore information in log messages
@@ -370,79 +372,94 @@
         return BAD_VALUE;
     }
 
-    std::lock_guard<std::mutex> lock(mCore->mMutex);
+    sp<IProducerListener> listener;
+    {
+        std::lock_guard<std::mutex> lock(mCore->mMutex);
 
-    if (mCore->mSharedBufferMode) {
-        BQ_LOGE("attachBuffer: cannot attach a buffer in shared buffer mode");
-        return BAD_VALUE;
-    }
-
-    // Make sure we don't have too many acquired buffers
-    int numAcquiredBuffers = 0;
-    for (int s : mCore->mActiveBuffers) {
-        if (mSlots[s].mBufferState.isAcquired()) {
-            ++numAcquiredBuffers;
+        if (mCore->mSharedBufferMode) {
+            BQ_LOGE("attachBuffer: cannot attach a buffer in shared buffer mode");
+            return BAD_VALUE;
         }
+
+        // Make sure we don't have too many acquired buffers
+        int numAcquiredBuffers = 0;
+        for (int s : mCore->mActiveBuffers) {
+            if (mSlots[s].mBufferState.isAcquired()) {
+                ++numAcquiredBuffers;
+            }
+        }
+
+        if (numAcquiredBuffers >= mCore->mMaxAcquiredBufferCount + 1) {
+            BQ_LOGE("attachBuffer: max acquired buffer count reached: %d "
+                    "(max %d)", numAcquiredBuffers,
+                    mCore->mMaxAcquiredBufferCount);
+            return INVALID_OPERATION;
+        }
+
+        if (buffer->getGenerationNumber() != mCore->mGenerationNumber) {
+            BQ_LOGE("attachBuffer: generation number mismatch [buffer %u] "
+                    "[queue %u]", buffer->getGenerationNumber(),
+                    mCore->mGenerationNumber);
+            return BAD_VALUE;
+        }
+
+        // Find a free slot to put the buffer into
+        int found = BufferQueueCore::INVALID_BUFFER_SLOT;
+        if (!mCore->mFreeSlots.empty()) {
+            auto slot = mCore->mFreeSlots.begin();
+            found = *slot;
+            mCore->mFreeSlots.erase(slot);
+        } else if (!mCore->mFreeBuffers.empty()) {
+            found = mCore->mFreeBuffers.front();
+            mCore->mFreeBuffers.remove(found);
+        }
+        if (found == BufferQueueCore::INVALID_BUFFER_SLOT) {
+            BQ_LOGE("attachBuffer: could not find free buffer slot");
+            return NO_MEMORY;
+        }
+
+#if COM_ANDROID_GRAPHICS_LIBGUI_FLAGS(BQ_CONSUMER_ATTACH_CALLBACK)
+        if (mCore->mBufferAttachedCbEnabled) {
+            listener = mCore->mConnectedProducerListener;
+        }
+#endif
+
+        mCore->mActiveBuffers.insert(found);
+        *outSlot = found;
+        ATRACE_BUFFER_INDEX(*outSlot);
+        BQ_LOGV("attachBuffer: returning slot %d", *outSlot);
+
+        mSlots[*outSlot].mGraphicBuffer = buffer;
+        mSlots[*outSlot].mBufferState.attachConsumer();
+        mSlots[*outSlot].mNeedsReallocation = true;
+        mSlots[*outSlot].mFence = Fence::NO_FENCE;
+        mSlots[*outSlot].mFrameNumber = 0;
+
+        // mAcquireCalled tells BufferQueue that it doesn't need to send a valid
+        // GraphicBuffer pointer on the next acquireBuffer call, which decreases
+        // Binder traffic by not un/flattening the GraphicBuffer. However, it
+        // requires that the consumer maintain a cached copy of the slot <--> buffer
+        // mappings, which is why the consumer doesn't need the valid pointer on
+        // acquire.
+        //
+        // The StreamSplitter is one of the primary users of the attach/detach
+        // logic, and while it is running, all buffers it acquires are immediately
+        // detached, and all buffers it eventually releases are ones that were
+        // attached (as opposed to having been obtained from acquireBuffer), so it
+        // doesn't make sense to maintain the slot/buffer mappings, which would
+        // become invalid for every buffer during detach/attach. By setting this to
+        // false, the valid GraphicBuffer pointer will always be sent with acquire
+        // for attached buffers.
+        mSlots[*outSlot].mAcquireCalled = false;
+
+        VALIDATE_CONSISTENCY();
     }
 
-    if (numAcquiredBuffers >= mCore->mMaxAcquiredBufferCount + 1) {
-        BQ_LOGE("attachBuffer: max acquired buffer count reached: %d "
-                "(max %d)", numAcquiredBuffers,
-                mCore->mMaxAcquiredBufferCount);
-        return INVALID_OPERATION;
+#if COM_ANDROID_GRAPHICS_LIBGUI_FLAGS(BQ_CONSUMER_ATTACH_CALLBACK)
+    if (listener != nullptr) {
+        listener->onBufferAttached();
     }
-
-    if (buffer->getGenerationNumber() != mCore->mGenerationNumber) {
-        BQ_LOGE("attachBuffer: generation number mismatch [buffer %u] "
-                "[queue %u]", buffer->getGenerationNumber(),
-                mCore->mGenerationNumber);
-        return BAD_VALUE;
-    }
-
-    // Find a free slot to put the buffer into
-    int found = BufferQueueCore::INVALID_BUFFER_SLOT;
-    if (!mCore->mFreeSlots.empty()) {
-        auto slot = mCore->mFreeSlots.begin();
-        found = *slot;
-        mCore->mFreeSlots.erase(slot);
-    } else if (!mCore->mFreeBuffers.empty()) {
-        found = mCore->mFreeBuffers.front();
-        mCore->mFreeBuffers.remove(found);
-    }
-    if (found == BufferQueueCore::INVALID_BUFFER_SLOT) {
-        BQ_LOGE("attachBuffer: could not find free buffer slot");
-        return NO_MEMORY;
-    }
-
-    mCore->mActiveBuffers.insert(found);
-    *outSlot = found;
-    ATRACE_BUFFER_INDEX(*outSlot);
-    BQ_LOGV("attachBuffer: returning slot %d", *outSlot);
-
-    mSlots[*outSlot].mGraphicBuffer = buffer;
-    mSlots[*outSlot].mBufferState.attachConsumer();
-    mSlots[*outSlot].mNeedsReallocation = true;
-    mSlots[*outSlot].mFence = Fence::NO_FENCE;
-    mSlots[*outSlot].mFrameNumber = 0;
-
-    // mAcquireCalled tells BufferQueue that it doesn't need to send a valid
-    // GraphicBuffer pointer on the next acquireBuffer call, which decreases
-    // Binder traffic by not un/flattening the GraphicBuffer. However, it
-    // requires that the consumer maintain a cached copy of the slot <--> buffer
-    // mappings, which is why the consumer doesn't need the valid pointer on
-    // acquire.
-    //
-    // The StreamSplitter is one of the primary users of the attach/detach
-    // logic, and while it is running, all buffers it acquires are immediately
-    // detached, and all buffers it eventually releases are ones that were
-    // attached (as opposed to having been obtained from acquireBuffer), so it
-    // doesn't make sense to maintain the slot/buffer mappings, which would
-    // become invalid for every buffer during detach/attach. By setting this to
-    // false, the valid GraphicBuffer pointer will always be sent with acquire
-    // for attached buffers.
-    mSlots[*outSlot].mAcquireCalled = false;
-
-    VALIDATE_CONSISTENCY();
+#endif
 
     return NO_ERROR;
 }
diff --git a/libs/gui/BufferQueueCore.cpp b/libs/gui/BufferQueueCore.cpp
index 648db67..e0c5b1f 100644
--- a/libs/gui/BufferQueueCore.cpp
+++ b/libs/gui/BufferQueueCore.cpp
@@ -96,6 +96,7 @@
         mLinkedToDeath(),
         mConnectedProducerListener(),
         mBufferReleasedCbEnabled(false),
+        mBufferAttachedCbEnabled(false),
         mSlots(),
         mQueue(),
         mFreeSlots(),
diff --git a/libs/gui/BufferQueueProducer.cpp b/libs/gui/BufferQueueProducer.cpp
index 69345a9..a4d105d 100644
--- a/libs/gui/BufferQueueProducer.cpp
+++ b/libs/gui/BufferQueueProducer.cpp
@@ -1360,6 +1360,9 @@
 #endif
                 mCore->mConnectedProducerListener = listener;
                 mCore->mBufferReleasedCbEnabled = listener->needsReleaseNotify();
+#if COM_ANDROID_GRAPHICS_LIBGUI_FLAGS(BQ_CONSUMER_ATTACH_CALLBACK)
+                mCore->mBufferAttachedCbEnabled = listener->needsAttachNotify();
+#endif
             }
             break;
         default:
diff --git a/libs/gui/IProducerListener.cpp b/libs/gui/IProducerListener.cpp
index 0683087..7700795 100644
--- a/libs/gui/IProducerListener.cpp
+++ b/libs/gui/IProducerListener.cpp
@@ -25,6 +25,9 @@
     ON_BUFFER_RELEASED = IBinder::FIRST_CALL_TRANSACTION,
     NEEDS_RELEASE_NOTIFY,
     ON_BUFFERS_DISCARDED,
+    ON_BUFFER_DETACHED,
+    ON_BUFFER_ATTACHED,
+    NEEDS_ATTACH_NOTIFY,
 };
 
 class BpProducerListener : public BpInterface<IProducerListener>
@@ -64,6 +67,38 @@
         data.writeInt32Vector(discardedSlots);
         remote()->transact(ON_BUFFERS_DISCARDED, data, &reply, IBinder::FLAG_ONEWAY);
     }
+
+#if COM_ANDROID_GRAPHICS_LIBGUI_FLAGS(BQ_CONSUMER_ATTACH_CALLBACK)
+    virtual void onBufferDetached(int slot) {
+        Parcel data, reply;
+        data.writeInterfaceToken(IProducerListener::getInterfaceDescriptor());
+        data.writeInt32(slot);
+        remote()->transact(ON_BUFFER_DETACHED, data, &reply, IBinder::FLAG_ONEWAY);
+    }
+
+    virtual void onBufferAttached() {
+        Parcel data, reply;
+        data.writeInterfaceToken(IProducerListener::getInterfaceDescriptor());
+        remote()->transact(ON_BUFFER_ATTACHED, data, &reply, IBinder::FLAG_ONEWAY);
+    }
+
+    virtual bool needsAttachNotify() {
+        bool result;
+        Parcel data, reply;
+        data.writeInterfaceToken(IProducerListener::getInterfaceDescriptor());
+        status_t err = remote()->transact(NEEDS_ATTACH_NOTIFY, data, &reply);
+        if (err != NO_ERROR) {
+            ALOGE("IProducerListener: binder call \'needsAttachNotify\' failed");
+            return true;
+        }
+        err = reply.readBool(&result);
+        if (err != NO_ERROR) {
+            ALOGE("IProducerListener: malformed binder reply");
+            return true;
+        }
+        return result;
+    }
+#endif
 };
 
 // Out-of-line virtual method definition to trigger vtable emission in this
@@ -115,6 +150,27 @@
             onBuffersDiscarded(discardedSlots);
             return NO_ERROR;
         }
+#if COM_ANDROID_GRAPHICS_LIBGUI_FLAGS(BQ_CONSUMER_ATTACH_CALLBACK)
+        case ON_BUFFER_DETACHED: {
+            CHECK_INTERFACE(IProducerListener, data, reply);
+            int slot;
+            status_t result = data.readInt32(&slot);
+            if (result != NO_ERROR) {
+                ALOGE("ON_BUFFER_DETACHED failed to read slot: %d", result);
+                return result;
+            }
+            onBufferDetached(slot);
+            return NO_ERROR;
+        }
+        case ON_BUFFER_ATTACHED:
+            CHECK_INTERFACE(IProducerListener, data, reply);
+            onBufferAttached();
+            return NO_ERROR;
+        case NEEDS_ATTACH_NOTIFY:
+            CHECK_INTERFACE(IProducerListener, data, reply);
+            reply->writeBool(needsAttachNotify());
+            return NO_ERROR;
+#endif
     }
     return BBinder::onTransact(code, data, reply, flags);
 }
diff --git a/libs/gui/include/gui/BufferQueueCore.h b/libs/gui/include/gui/BufferQueueCore.h
index bb52c8e..d5dd7c8 100644
--- a/libs/gui/include/gui/BufferQueueCore.h
+++ b/libs/gui/include/gui/BufferQueueCore.h
@@ -192,6 +192,10 @@
     // callback is registered by the listener. When set to false,
     // mConnectedProducerListener will not trigger onBufferReleased() callback.
     bool mBufferReleasedCbEnabled;
+    // mBufferAttachedCbEnabled is used to indicate whether onBufferAttached()
+    // callback is registered by the listener. When set to false,
+    // mConnectedProducerListener will not trigger onBufferAttached() callback.
+    bool mBufferAttachedCbEnabled;
 
     // mSlots is an array of buffer slots that must be mirrored on the producer
     // side. This allows buffer ownership to be transferred between the producer
diff --git a/libs/gui/include/gui/IProducerListener.h b/libs/gui/include/gui/IProducerListener.h
index b15f501..3dcc6b6 100644
--- a/libs/gui/include/gui/IProducerListener.h
+++ b/libs/gui/include/gui/IProducerListener.h
@@ -25,6 +25,8 @@
 #include <hidl/HybridInterface.h>
 #include <utils/RefBase.h>
 
+#include <com_android_graphics_libgui_flags.h>
+
 namespace android {
 
 // ProducerListener is the interface through which the BufferQueue notifies the
@@ -55,6 +57,16 @@
     // This is called without any lock held and can be called concurrently by
     // multiple threads.
     virtual void onBufferDetached(int /*slot*/) {} // Asynchronous
+#if COM_ANDROID_GRAPHICS_LIBGUI_FLAGS(BQ_CONSUMER_ATTACH_CALLBACK)
+    // onBufferAttached is called from IGraphicBufferConsumer::attachBuffer to
+    // notify the producer that a buffer is attached.
+    //
+    // This is called without any lock held and can be called concurrently by
+    // multiple threads. This callback is enabled only when needsAttachNotify()
+    // returns {@code true}.
+    virtual void onBufferAttached() {} // Asynchronous
+    virtual bool needsAttachNotify() { return false; }
+#endif
 };
 
 #ifndef NO_BINDER
diff --git a/libs/gui/tests/BufferQueue_test.cpp b/libs/gui/tests/BufferQueue_test.cpp
index 272c5ed..590e2c8 100644
--- a/libs/gui/tests/BufferQueue_test.cpp
+++ b/libs/gui/tests/BufferQueue_test.cpp
@@ -1262,6 +1262,91 @@
     ASSERT_TRUE(result == WOULD_BLOCK || result == TIMED_OUT || result == INVALID_OPERATION);
 }
 
+#if COM_ANDROID_GRAPHICS_LIBGUI_FLAGS(BQ_CONSUMER_ATTACH_CALLBACK)
+struct BufferAttachedListener : public BnProducerListener {
+public:
+    BufferAttachedListener(bool enable) : mEnabled(enable), mAttached(0) {}
+    virtual ~BufferAttachedListener() = default;
+
+    virtual void onBufferReleased() {}
+    virtual bool needsReleaseNotify() { return true; }
+    virtual void onBufferAttached() {
+        ++mAttached;
+    }
+    virtual bool needsAttachNotify() { return mEnabled; }
+
+    int getNumAttached() const { return mAttached; }
+private:
+    const bool mEnabled;
+    int mAttached;
+};
+
+TEST_F(BufferQueueTest, TestConsumerAttachProducerListener) {
+    createBufferQueue();
+    sp<MockConsumer> mc1(new MockConsumer);
+    ASSERT_EQ(OK, mConsumer->consumerConnect(mc1, true));
+    IGraphicBufferProducer::QueueBufferOutput output;
+    // Do not enable attach callback.
+    sp<BufferAttachedListener> pl1(new BufferAttachedListener(false));
+    ASSERT_EQ(OK, mProducer->connect(pl1, NATIVE_WINDOW_API_CPU, true, &output));
+    ASSERT_EQ(OK, mProducer->setDequeueTimeout(0));
+    ASSERT_EQ(OK, mConsumer->setMaxAcquiredBufferCount(1));
+
+    sp<Fence> fence = Fence::NO_FENCE;
+    sp<GraphicBuffer> buffer = nullptr;
+
+    int slot;
+    status_t result = OK;
+
+    ASSERT_EQ(OK, mProducer->setMaxDequeuedBufferCount(1));
+
+    result = mProducer->dequeueBuffer(&slot, &fence, 0, 0, 0,
+                                      GRALLOC_USAGE_SW_READ_RARELY, nullptr, nullptr);
+    ASSERT_EQ(IGraphicBufferProducer::BUFFER_NEEDS_REALLOCATION, result);
+    ASSERT_EQ(OK, mProducer->requestBuffer(slot, &buffer));
+    ASSERT_EQ(OK, mProducer->detachBuffer(slot));
+
+    // Check # of attach is zero.
+    ASSERT_EQ(0, pl1->getNumAttached());
+
+    // Attach a buffer and check the callback was not called.
+    ASSERT_EQ(OK, mConsumer->attachBuffer(&slot, buffer));
+    ASSERT_EQ(0, pl1->getNumAttached());
+
+    mProducer = nullptr;
+    mConsumer = nullptr;
+    createBufferQueue();
+
+    sp<MockConsumer> mc2(new MockConsumer);
+    ASSERT_EQ(OK, mConsumer->consumerConnect(mc2, true));
+    // Enable attach callback.
+    sp<BufferAttachedListener> pl2(new BufferAttachedListener(true));
+    ASSERT_EQ(OK, mProducer->connect(pl2, NATIVE_WINDOW_API_CPU, true, &output));
+    ASSERT_EQ(OK, mProducer->setDequeueTimeout(0));
+    ASSERT_EQ(OK, mConsumer->setMaxAcquiredBufferCount(1));
+
+    fence = Fence::NO_FENCE;
+    buffer = nullptr;
+
+    result = OK;
+
+    ASSERT_EQ(OK, mProducer->setMaxDequeuedBufferCount(1));
+
+    result = mProducer->dequeueBuffer(&slot, &fence, 0, 0, 0,
+                                      GRALLOC_USAGE_SW_READ_RARELY, nullptr, nullptr);
+    ASSERT_EQ(IGraphicBufferProducer::BUFFER_NEEDS_REALLOCATION, result);
+    ASSERT_EQ(OK, mProducer->requestBuffer(slot, &buffer));
+    ASSERT_EQ(OK, mProducer->detachBuffer(slot));
+
+    // Check # of attach is zero.
+    ASSERT_EQ(0, pl2->getNumAttached());
+
+    // Attach a buffer and check the callback was called.
+    ASSERT_EQ(OK, mConsumer->attachBuffer(&slot, buffer));
+    ASSERT_EQ(1, pl2->getNumAttached());
+}
+#endif
+
 TEST_F(BufferQueueTest, TestStaleBufferHandleSentAfterDisconnect) {
     createBufferQueue();
     sp<MockConsumer> mc(new MockConsumer);