diff --git a/neuralnetworks/1.2/vts/functional/Android.bp b/neuralnetworks/1.2/vts/functional/Android.bp
index fc727b7..bfb8719 100644
--- a/neuralnetworks/1.2/vts/functional/Android.bp
+++ b/neuralnetworks/1.2/vts/functional/Android.bp
@@ -14,28 +14,12 @@
 // limitations under the License.
 //
 
-cc_library_static {
-    name: "VtsHalNeuralNetworksV1_2Callbacks",
-    defaults: ["VtsHalTargetTestDefaults"],
-    export_include_dirs: ["include"],
-    srcs: [
-        "Callbacks.cpp",
-    ],
-    static_libs: [
-        "android.hardware.neuralnetworks@1.0",
-        "android.hardware.neuralnetworks@1.1",
-        "android.hardware.neuralnetworks@1.2",
-    ],
-    header_libs: [
-        "libbase_headers",
-    ]
-}
-
 cc_test {
     name: "VtsHalNeuralnetworksV1_2TargetTest",
     defaults: ["VtsHalTargetTestDefaults"],
     srcs: [
         "BasicTests.cpp",
+        "Callbacks.cpp",
         "CompilationCachingTests.cpp",
         "GeneratedTestHarness.cpp",
         "TestAssertions.cpp",
@@ -61,7 +45,6 @@
         "libneuralnetworks_generated_test_harness",
         "libneuralnetworks_utils",
         "VtsHalNeuralNetworksV1_0_utils",
-        "VtsHalNeuralNetworksV1_2Callbacks",
     ],
     whole_static_libs: [
         "neuralnetworks_generated_V1_0_example",
diff --git a/neuralnetworks/1.3/vts/functional/Android.bp b/neuralnetworks/1.3/vts/functional/Android.bp
deleted file mode 100644
index 90ce852..0000000
--- a/neuralnetworks/1.3/vts/functional/Android.bp
+++ /dev/null
@@ -1,58 +0,0 @@
-//
-// Copyright (C) 2019 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.
-//
-
-cc_test {
-    name: "VtsHalNeuralNetworksV1_3TargetTest",
-    defaults: ["VtsHalTargetTestDefaults"],
-    srcs: [
-        "BasicTests.cpp",
-        "CompilationCachingTests.cpp",
-        "GeneratedTestHarness.cpp",
-        "TestAssertions.cpp",
-        "ValidateBurst.cpp",
-        "ValidateModel.cpp",
-        "ValidateRequest.cpp",
-        "VtsHalNeuralnetworks.cpp",
-    ],
-    shared_libs: [
-        "libfmq",
-        "libnativewindow",
-    ],
-    static_libs: [
-        "android.hardware.neuralnetworks@1.0",
-        "android.hardware.neuralnetworks@1.1",
-        "android.hardware.neuralnetworks@1.2",
-        "android.hardware.neuralnetworks@1.3",
-        "android.hidl.allocator@1.0",
-        "android.hidl.memory@1.0",
-        "libgmock",
-        "libhidlmemory",
-        "libneuralnetworks_generated_test_harness",
-        "libneuralnetworks_utils",
-        "VtsHalNeuralNetworksV1_0_utils",
-        "VtsHalNeuralNetworksV1_2Callbacks",
-    ],
-    whole_static_libs: [
-        "neuralnetworks_generated_V1_0_example",
-        "neuralnetworks_generated_V1_1_example",
-        "neuralnetworks_generated_V1_2_example",
-        "neuralnetworks_generated_V1_3_example",
-    ],
-    header_libs: [
-        "libneuralnetworks_headers",
-    ],
-    test_suites: ["general-tests"],
-}
diff --git a/neuralnetworks/1.3/vts/functional/BasicTests.cpp b/neuralnetworks/1.3/vts/functional/BasicTests.cpp
index b64dc2f..8e82c53 100644
--- a/neuralnetworks/1.3/vts/functional/BasicTests.cpp
+++ b/neuralnetworks/1.3/vts/functional/BasicTests.cpp
@@ -18,14 +18,11 @@
 
 #include "VtsHalNeuralnetworks.h"
 
-namespace android::hardware::neuralnetworks::V1_3::vts::functional {
+namespace android::hardware::neuralnetworks::V1_2::vts::functional {
 
 using V1_0::DeviceStatus;
 using V1_0::ErrorStatus;
 using V1_0::PerformanceInfo;
-using V1_2::Constant;
-using V1_2::DeviceType;
-using V1_2::Extension;
 
 // create device test
 TEST_P(NeuralnetworksHidlTest, CreateDevice) {}
@@ -40,7 +37,7 @@
 // initialization
 TEST_P(NeuralnetworksHidlTest, GetCapabilitiesTest) {
     using OperandPerformance = Capabilities::OperandPerformance;
-    Return<void> ret = kDevice->getCapabilities_1_3([](ErrorStatus status,
+    Return<void> ret = kDevice->getCapabilities_1_2([](ErrorStatus status,
                                                        const Capabilities& capabilities) {
         EXPECT_EQ(ErrorStatus::NONE, status);
 
@@ -61,4 +58,57 @@
     });
     EXPECT_TRUE(ret.isOk());
 }
-}  // namespace android::hardware::neuralnetworks::V1_3::vts::functional
+
+// device version test
+TEST_P(NeuralnetworksHidlTest, GetDeviceVersionStringTest) {
+    Return<void> ret =
+            kDevice->getVersionString([](ErrorStatus status, const hidl_string& version) {
+                EXPECT_EQ(ErrorStatus::NONE, status);
+                EXPECT_LT(0, version.size());
+            });
+    EXPECT_TRUE(ret.isOk());
+}
+
+// device type test
+TEST_P(NeuralnetworksHidlTest, GetDeviceTypeTest) {
+    Return<void> ret = kDevice->getType([](ErrorStatus status, DeviceType type) {
+        EXPECT_EQ(ErrorStatus::NONE, status);
+        EXPECT_TRUE(type == DeviceType::OTHER || type == DeviceType::CPU ||
+                    type == DeviceType::GPU || type == DeviceType::ACCELERATOR);
+    });
+    EXPECT_TRUE(ret.isOk());
+}
+
+// device supported extensions test
+TEST_P(NeuralnetworksHidlTest, GetDeviceSupportedExtensionsTest) {
+    Return<void> ret = kDevice->getSupportedExtensions(
+            [](ErrorStatus status, const hidl_vec<Extension>& extensions) {
+                EXPECT_EQ(ErrorStatus::NONE, status);
+                for (auto& extension : extensions) {
+                    std::string extensionName = extension.name;
+                    EXPECT_FALSE(extensionName.empty());
+                    for (char c : extensionName) {
+                        EXPECT_TRUE(('a' <= c && c <= 'z') || ('0' <= c && c <= '9') || c == '_' ||
+                                    c == '.')
+                                << "Extension name contains an illegal character: " << c;
+                    }
+                    EXPECT_NE(extensionName.find('.'), std::string::npos)
+                            << "Extension name must start with the reverse domain name of the "
+                               "vendor";
+                }
+            });
+    EXPECT_TRUE(ret.isOk());
+}
+
+// getNumberOfCacheFilesNeeded test
+TEST_P(NeuralnetworksHidlTest, getNumberOfCacheFilesNeeded) {
+    Return<void> ret = kDevice->getNumberOfCacheFilesNeeded(
+            [](ErrorStatus status, uint32_t numModelCache, uint32_t numDataCache) {
+                EXPECT_EQ(ErrorStatus::NONE, status);
+                EXPECT_LE(numModelCache,
+                          static_cast<uint32_t>(Constant::MAX_NUMBER_OF_CACHE_FILES));
+                EXPECT_LE(numDataCache, static_cast<uint32_t>(Constant::MAX_NUMBER_OF_CACHE_FILES));
+            });
+    EXPECT_TRUE(ret.isOk());
+}
+}  // namespace android::hardware::neuralnetworks::V1_2::vts::functional
diff --git a/neuralnetworks/1.3/vts/functional/Callbacks.cpp b/neuralnetworks/1.3/vts/functional/Callbacks.cpp
new file mode 100644
index 0000000..3972ad6
--- /dev/null
+++ b/neuralnetworks/1.3/vts/functional/Callbacks.cpp
@@ -0,0 +1,143 @@
+/*
+ * Copyright (C) 2019 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.
+ */
+
+#define LOG_TAG "Callbacks"
+
+#include "1.2/Callbacks.h"
+
+#include <android-base/logging.h>
+
+#include <limits>
+
+namespace android::hardware::neuralnetworks::V1_2::implementation {
+
+using V1_0::ErrorStatus;
+
+constexpr Timing kNoTiming = {.timeOnDevice = std::numeric_limits<uint64_t>::max(),
+                              .timeInDriver = std::numeric_limits<uint64_t>::max()};
+
+// PreparedModelCallback methods begin here
+
+Return<void> PreparedModelCallback::notify(ErrorStatus errorStatus,
+                                           const sp<V1_0::IPreparedModel>& preparedModel) {
+    {
+        std::lock_guard<std::mutex> hold(mMutex);
+
+        // quick-return if object has already been notified
+        if (mNotified) {
+            return Void();
+        }
+
+        // store results and mark as notified
+        mErrorStatus = errorStatus;
+        mPreparedModel = preparedModel;
+        mNotified = true;
+    }
+
+    mCondition.notify_all();
+    return Void();
+}
+
+Return<void> PreparedModelCallback::notify_1_2(ErrorStatus errorStatus,
+                                               const sp<V1_2::IPreparedModel>& preparedModel) {
+    return notify(errorStatus, preparedModel);
+}
+
+void PreparedModelCallback::wait() const {
+    std::unique_lock<std::mutex> lock(mMutex);
+    mCondition.wait(lock, [this] { return mNotified; });
+}
+
+ErrorStatus PreparedModelCallback::getStatus() const {
+    wait();
+    return mErrorStatus;
+}
+
+sp<V1_0::IPreparedModel> PreparedModelCallback::getPreparedModel() const {
+    wait();
+    return mPreparedModel;
+}
+
+// ExecutionCallback methods begin here
+
+Return<void> ExecutionCallback::notify(ErrorStatus errorStatus) {
+    notifyInternal(errorStatus, {}, kNoTiming);
+    return Void();
+}
+
+Return<void> ExecutionCallback::notify_1_2(ErrorStatus errorStatus,
+                                           const hidl_vec<OutputShape>& outputShapes,
+                                           const Timing& timing) {
+    if (errorStatus == ErrorStatus::OUTPUT_INSUFFICIENT_SIZE) {
+        // outputShapes must not be empty if OUTPUT_INSUFFICIENT_SIZE.
+        if (outputShapes.size() == 0) {
+            LOG(ERROR) << "Notified with empty output shape vector when OUTPUT_INSUFFICIENT_SIZE";
+            notifyInternal(ErrorStatus::GENERAL_FAILURE, {}, kNoTiming);
+            return Void();
+        }
+    } else if (errorStatus != ErrorStatus::NONE) {
+        // outputShapes must be empty if errorStatus is neither NONE nor OUTPUT_INSUFFICIENT_SIZE.
+        if (outputShapes.size() != 0) {
+            LOG(ERROR) << "Notified with non-empty output shape vector when error status is "
+                          "neither NONE nor OUTPUT_INSUFFICIENT_SIZE";
+            notifyInternal(ErrorStatus::GENERAL_FAILURE, {}, kNoTiming);
+            return Void();
+        }
+    }
+    notifyInternal(errorStatus, outputShapes, timing);
+    return Void();
+}
+
+void ExecutionCallback::wait() const {
+    std::unique_lock<std::mutex> lock(mMutex);
+    mCondition.wait(lock, [this] { return mNotified; });
+}
+
+ErrorStatus ExecutionCallback::getStatus() const {
+    wait();
+    return mErrorStatus;
+}
+
+const std::vector<OutputShape>& ExecutionCallback::getOutputShapes() const {
+    wait();
+    return mOutputShapes;
+}
+
+Timing ExecutionCallback::getTiming() const {
+    wait();
+    return mTiming;
+}
+
+void ExecutionCallback::notifyInternal(ErrorStatus errorStatus,
+                                       const hidl_vec<OutputShape>& outputShapes,
+                                       const Timing& timing) {
+    {
+        std::lock_guard<std::mutex> hold(mMutex);
+
+        // quick-return if object has already been notified
+        if (mNotified) {
+            return;
+        }
+
+        mErrorStatus = errorStatus;
+        mOutputShapes = outputShapes;
+        mTiming = timing;
+        mNotified = true;
+    }
+    mCondition.notify_all();
+}
+
+}  // namespace android::hardware::neuralnetworks::V1_2::implementation
diff --git a/neuralnetworks/1.3/vts/functional/CompilationCachingTests.cpp b/neuralnetworks/1.3/vts/functional/CompilationCachingTests.cpp
index 0ac4738..2130a76 100644
--- a/neuralnetworks/1.3/vts/functional/CompilationCachingTests.cpp
+++ b/neuralnetworks/1.3/vts/functional/CompilationCachingTests.cpp
@@ -45,15 +45,12 @@
 const test_helper::TestModel& get_test_model();
 }  // namespace generated_tests::mobilenet_quantized
 
-namespace android::hardware::neuralnetworks::V1_3::vts::functional {
+namespace android::hardware::neuralnetworks::V1_2::vts::functional {
 
 using namespace test_helper;
+using implementation::PreparedModelCallback;
 using V1_0::ErrorStatus;
 using V1_1::ExecutionPreference;
-using V1_2::Constant;
-using V1_2::IPreparedModel;
-using V1_2::OperationType;
-using V1_2::implementation::PreparedModelCallback;
 
 namespace float32_model {
 
@@ -305,7 +302,7 @@
     // See if the service can handle the model.
     bool isModelFullySupported(const Model& model) {
         bool fullySupportsModel = false;
-        Return<void> supportedCall = kDevice->getSupportedOperations_1_3(
+        Return<void> supportedCall = kDevice->getSupportedOperations_1_2(
                 model,
                 [&fullySupportsModel, &model](ErrorStatus status, const hidl_vec<bool>& supported) {
                     ASSERT_EQ(ErrorStatus::NONE, status);
@@ -326,7 +323,7 @@
         sp<PreparedModelCallback> preparedModelCallback = new PreparedModelCallback();
         hidl_array<uint8_t, sizeof(mToken)> cacheToken(mToken);
         Return<ErrorStatus> prepareLaunchStatus =
-                kDevice->prepareModel_1_3(model, ExecutionPreference::FAST_SINGLE_ANSWER,
+                kDevice->prepareModel_1_2(model, ExecutionPreference::FAST_SINGLE_ANSWER,
                                           modelCache, dataCache, cacheToken, preparedModelCallback);
         ASSERT_TRUE(prepareLaunchStatus.isOk());
         ASSERT_EQ(static_cast<ErrorStatus>(prepareLaunchStatus), ErrorStatus::NONE);
@@ -1374,4 +1371,4 @@
                                          testing::Range(0U, 10U)),
                         printCompilationCachingSecurityTest);
 
-}  // namespace android::hardware::neuralnetworks::V1_3::vts::functional
+}  // namespace android::hardware::neuralnetworks::V1_2::vts::functional
diff --git a/neuralnetworks/1.3/vts/functional/GeneratedTestHarness.cpp b/neuralnetworks/1.3/vts/functional/GeneratedTestHarness.cpp
index 16a7d70..2beec98 100644
--- a/neuralnetworks/1.3/vts/functional/GeneratedTestHarness.cpp
+++ b/neuralnetworks/1.3/vts/functional/GeneratedTestHarness.cpp
@@ -27,9 +27,6 @@
 #include <android/hardware/neuralnetworks/1.2/IExecutionCallback.h>
 #include <android/hardware/neuralnetworks/1.2/IPreparedModel.h>
 #include <android/hardware/neuralnetworks/1.2/IPreparedModelCallback.h>
-#include <android/hardware/neuralnetworks/1.2/types.h>
-#include <android/hardware/neuralnetworks/1.3/IDevice.h>
-#include <android/hardware/neuralnetworks/1.3/types.h>
 #include <android/hidl/allocator/1.0/IAllocator.h>
 #include <android/hidl/memory/1.0/IMemory.h>
 #include <hidlmemory/mapping.h>
@@ -47,24 +44,17 @@
 #include "Utils.h"
 #include "VtsHalNeuralnetworks.h"
 
-namespace android::hardware::neuralnetworks::V1_3::vts::functional {
+namespace android::hardware::neuralnetworks::V1_2::vts::functional {
 
 using namespace test_helper;
 using hidl::memory::V1_0::IMemory;
+using implementation::ExecutionCallback;
+using implementation::PreparedModelCallback;
 using V1_0::DataLocation;
 using V1_0::ErrorStatus;
 using V1_0::OperandLifeTime;
 using V1_0::Request;
 using V1_1::ExecutionPreference;
-using V1_2::Constant;
-using V1_2::IPreparedModel;
-using V1_2::MeasureTiming;
-using V1_2::OperationType;
-using V1_2::OutputShape;
-using V1_2::SymmPerChannelQuantParams;
-using V1_2::Timing;
-using V1_2::implementation::ExecutionCallback;
-using V1_2::implementation::PreparedModelCallback;
 using HidlToken = hidl_array<uint8_t, static_cast<uint32_t>(Constant::BYTE_SIZE_OF_CACHE_TOKEN)>;
 
 enum class OutputType { FULLY_SPECIFIED, UNSPECIFIED, INSUFFICIENT };
@@ -415,4 +405,4 @@
 INSTANTIATE_GENERATED_TEST(DynamicOutputShapeTest,
                            [](const TestModel& testModel) { return !testModel.expectFailure; });
 
-}  // namespace android::hardware::neuralnetworks::V1_3::vts::functional
+}  // namespace android::hardware::neuralnetworks::V1_2::vts::functional
diff --git a/neuralnetworks/1.3/vts/functional/GeneratedTestHarness.h b/neuralnetworks/1.3/vts/functional/GeneratedTestHarness.h
index b9277cf..dfc980c 100644
--- a/neuralnetworks/1.3/vts/functional/GeneratedTestHarness.h
+++ b/neuralnetworks/1.3/vts/functional/GeneratedTestHarness.h
@@ -14,19 +14,19 @@
  * limitations under the License.
  */
 
-#ifndef ANDROID_HARDWARE_NEURALNETWORKS_V1_3_GENERATED_TEST_HARNESS_H
-#define ANDROID_HARDWARE_NEURALNETWORKS_V1_3_GENERATED_TEST_HARNESS_H
+#ifndef ANDROID_HARDWARE_NEURALNETWORKS_V1_2_GENERATED_TEST_HARNESS_H
+#define ANDROID_HARDWARE_NEURALNETWORKS_V1_2_GENERATED_TEST_HARNESS_H
 
+#include <android/hardware/neuralnetworks/1.2/IDevice.h>
 #include <android/hardware/neuralnetworks/1.2/IPreparedModel.h>
-#include <android/hardware/neuralnetworks/1.3/IDevice.h>
-#include <android/hardware/neuralnetworks/1.3/types.h>
+#include <android/hardware/neuralnetworks/1.2/types.h>
 #include <functional>
 #include <vector>
 #include "1.0/Utils.h"
 #include "TestHarness.h"
 #include "VtsHalNeuralnetworks.h"
 
-namespace android::hardware::neuralnetworks::V1_3::vts::functional {
+namespace android::hardware::neuralnetworks::V1_2::vts::functional {
 
 using NamedModel = Named<const test_helper::TestModel*>;
 using GeneratedTestParam = std::tuple<NamedDevice, NamedModel>;
@@ -55,12 +55,11 @@
 
 Model createModel(const test_helper::TestModel& testModel);
 
-void PrepareModel(const sp<IDevice>& device, const Model& model,
-                  sp<V1_2::IPreparedModel>* preparedModel);
+void PrepareModel(const sp<IDevice>& device, const Model& model, sp<IPreparedModel>* preparedModel);
 
-void EvaluatePreparedModel(const sp<V1_2::IPreparedModel>& preparedModel,
+void EvaluatePreparedModel(const sp<IPreparedModel>& preparedModel,
                            const test_helper::TestModel& testModel, bool testDynamicOutputShape);
 
-}  // namespace android::hardware::neuralnetworks::V1_3::vts::functional
+}  // namespace android::hardware::neuralnetworks::V1_2::vts::functional
 
-#endif  // ANDROID_HARDWARE_NEURALNETWORKS_V1_3_GENERATED_TEST_HARNESS_H
+#endif  // ANDROID_HARDWARE_NEURALNETWORKS_V1_2_GENERATED_TEST_HARNESS_H
diff --git a/neuralnetworks/1.3/vts/functional/TestAssertions.cpp b/neuralnetworks/1.3/vts/functional/TestAssertions.cpp
index 7361078..a0aa3c3 100644
--- a/neuralnetworks/1.3/vts/functional/TestAssertions.cpp
+++ b/neuralnetworks/1.3/vts/functional/TestAssertions.cpp
@@ -14,10 +14,10 @@
  * limitations under the License.
  */
 
-#include <android/hardware/neuralnetworks/1.3/types.h>
+#include <android/hardware/neuralnetworks/1.2/types.h>
 #include "TestHarness.h"
 
-namespace android::hardware::neuralnetworks::V1_3 {
+namespace android::hardware::neuralnetworks::V1_2 {
 
 // Make sure that the HIDL enums are compatible with the values defined in
 // frameworks/ml/nn/tools/test_generator/test_harness/include/TestHarness.h.
@@ -25,8 +25,6 @@
 #define CHECK_TEST_ENUM(EnumType, enumValue) \
     static_assert(static_cast<EnumType>(Test##EnumType::enumValue) == EnumType::enumValue)
 
-using V1_2::OperationType;
-
 CHECK_TEST_ENUM(OperandType, FLOAT32);
 CHECK_TEST_ENUM(OperandType, INT32);
 CHECK_TEST_ENUM(OperandType, UINT32);
@@ -41,7 +39,6 @@
 CHECK_TEST_ENUM(OperandType, TENSOR_QUANT8_SYMM_PER_CHANNEL);
 CHECK_TEST_ENUM(OperandType, TENSOR_QUANT16_ASYMM);
 CHECK_TEST_ENUM(OperandType, TENSOR_QUANT8_SYMM);
-CHECK_TEST_ENUM(OperandType, TENSOR_QUANT8_ASYMM_SIGNED);
 
 CHECK_TEST_ENUM(OperationType, ADD);
 CHECK_TEST_ENUM(OperationType, AVERAGE_POOL_2D);
@@ -141,4 +138,4 @@
 
 #undef CHECK_TEST_ENUM
 
-}  // namespace android::hardware::neuralnetworks::V1_3
+}  // namespace android::hardware::neuralnetworks::V1_2
diff --git a/neuralnetworks/1.3/vts/functional/ValidateBurst.cpp b/neuralnetworks/1.3/vts/functional/ValidateBurst.cpp
index 95f9f42..1d4493d 100644
--- a/neuralnetworks/1.3/vts/functional/ValidateBurst.cpp
+++ b/neuralnetworks/1.3/vts/functional/ValidateBurst.cpp
@@ -28,20 +28,13 @@
 #include <android-base/logging.h>
 #include <cstring>
 
-namespace android::hardware::neuralnetworks::V1_3::vts::functional {
+namespace android::hardware::neuralnetworks::V1_2::vts::functional {
 
 using nn::ExecutionBurstController;
 using nn::RequestChannelSender;
 using nn::ResultChannelReceiver;
 using V1_0::ErrorStatus;
 using V1_0::Request;
-using V1_2::FmqRequestDatum;
-using V1_2::FmqResultDatum;
-using V1_2::IBurstCallback;
-using V1_2::IBurstContext;
-using V1_2::IPreparedModel;
-using V1_2::MeasureTiming;
-using V1_2::Timing;
 using ExecutionBurstCallback = ExecutionBurstController::ExecutionBurstCallback;
 
 // This constant value represents the length of an FMQ that is large enough to
@@ -404,4 +397,4 @@
     ASSERT_NO_FATAL_FAILURE(validateBurstSanitized(preparedModel, request));
 }
 
-}  // namespace android::hardware::neuralnetworks::V1_3::vts::functional
+}  // namespace android::hardware::neuralnetworks::V1_2::vts::functional
diff --git a/neuralnetworks/1.3/vts/functional/ValidateModel.cpp b/neuralnetworks/1.3/vts/functional/ValidateModel.cpp
index 44b32a9..30530be 100644
--- a/neuralnetworks/1.3/vts/functional/ValidateModel.cpp
+++ b/neuralnetworks/1.3/vts/functional/ValidateModel.cpp
@@ -21,26 +21,21 @@
 #include "GeneratedTestHarness.h"
 #include "VtsHalNeuralnetworks.h"
 
-namespace android::hardware::neuralnetworks::V1_3::vts::functional {
+namespace android::hardware::neuralnetworks::V1_2::vts::functional {
 
+using implementation::PreparedModelCallback;
 using V1_0::ErrorStatus;
 using V1_0::OperandLifeTime;
 using V1_1::ExecutionPreference;
-using V1_2::IPreparedModel;
-using V1_2::OperationType;
-using V1_2::OperationTypeRange;
-using V1_2::SymmPerChannelQuantParams;
-using V1_2::implementation::PreparedModelCallback;
-using HidlToken =
-        hidl_array<uint8_t, static_cast<uint32_t>(V1_2::Constant::BYTE_SIZE_OF_CACHE_TOKEN)>;
+using HidlToken = hidl_array<uint8_t, static_cast<uint32_t>(Constant::BYTE_SIZE_OF_CACHE_TOKEN)>;
 
 ///////////////////////// UTILITY FUNCTIONS /////////////////////////
 
 static void validateGetSupportedOperations(const sp<IDevice>& device, const std::string& message,
                                            const Model& model) {
-    SCOPED_TRACE(message + " [getSupportedOperations_1_3]");
+    SCOPED_TRACE(message + " [getSupportedOperations_1_2]");
 
-    Return<void> ret = device->getSupportedOperations_1_3(
+    Return<void> ret = device->getSupportedOperations_1_2(
             model, [&](ErrorStatus status, const hidl_vec<bool>&) {
                 EXPECT_EQ(ErrorStatus::INVALID_ARGUMENT, status);
             });
@@ -49,11 +44,11 @@
 
 static void validatePrepareModel(const sp<IDevice>& device, const std::string& message,
                                  const Model& model, ExecutionPreference preference) {
-    SCOPED_TRACE(message + " [prepareModel_1_3]");
+    SCOPED_TRACE(message + " [prepareModel_1_2]");
 
     sp<PreparedModelCallback> preparedModelCallback = new PreparedModelCallback();
     Return<ErrorStatus> prepareLaunchStatus =
-            device->prepareModel_1_3(model, preference, hidl_vec<hidl_handle>(),
+            device->prepareModel_1_2(model, preference, hidl_vec<hidl_handle>(),
                                      hidl_vec<hidl_handle>(), HidlToken(), preparedModelCallback);
     ASSERT_TRUE(prepareLaunchStatus.isOk());
     ASSERT_EQ(ErrorStatus::INVALID_ARGUMENT, static_cast<ErrorStatus>(prepareLaunchStatus));
@@ -715,4 +710,4 @@
     mutateExecutionPreferenceTest(device, model);
 }
 
-}  // namespace android::hardware::neuralnetworks::V1_3::vts::functional
+}  // namespace android::hardware::neuralnetworks::V1_2::vts::functional
diff --git a/neuralnetworks/1.3/vts/functional/ValidateRequest.cpp b/neuralnetworks/1.3/vts/functional/ValidateRequest.cpp
index 6122123..f25ee62 100644
--- a/neuralnetworks/1.3/vts/functional/ValidateRequest.cpp
+++ b/neuralnetworks/1.3/vts/functional/ValidateRequest.cpp
@@ -24,15 +24,11 @@
 #include "Utils.h"
 #include "VtsHalNeuralnetworks.h"
 
-namespace android::hardware::neuralnetworks::V1_3::vts::functional {
+namespace android::hardware::neuralnetworks::V1_2::vts::functional {
 
+using implementation::ExecutionCallback;
 using V1_0::ErrorStatus;
 using V1_0::Request;
-using V1_2::IPreparedModel;
-using V1_2::MeasureTiming;
-using V1_2::OutputShape;
-using V1_2::Timing;
-using V1_2::implementation::ExecutionCallback;
 
 ///////////////////////// UTILITY FUNCTIONS /////////////////////////
 
@@ -169,4 +165,4 @@
     ASSERT_TRUE(executeStatus.isOk());
 }
 
-}  // namespace android::hardware::neuralnetworks::V1_3::vts::functional
+}  // namespace android::hardware::neuralnetworks::V1_2::vts::functional
diff --git a/neuralnetworks/1.3/vts/functional/VtsHalNeuralnetworks.cpp b/neuralnetworks/1.3/vts/functional/VtsHalNeuralnetworks.cpp
index 4f0e150..4fbd0e2 100644
--- a/neuralnetworks/1.3/vts/functional/VtsHalNeuralnetworks.cpp
+++ b/neuralnetworks/1.3/vts/functional/VtsHalNeuralnetworks.cpp
@@ -26,15 +26,13 @@
 #include "GeneratedTestHarness.h"
 #include "TestHarness.h"
 
-namespace android::hardware::neuralnetworks::V1_3::vts::functional {
+namespace android::hardware::neuralnetworks::V1_2::vts::functional {
 
-using HidlToken =
-        hidl_array<uint8_t, static_cast<uint32_t>(V1_2::Constant::BYTE_SIZE_OF_CACHE_TOKEN)>;
+using implementation::PreparedModelCallback;
+using HidlToken = hidl_array<uint8_t, static_cast<uint32_t>(Constant::BYTE_SIZE_OF_CACHE_TOKEN)>;
 using V1_0::ErrorStatus;
 using V1_0::Request;
 using V1_1::ExecutionPreference;
-using V1_2::IPreparedModel;
-using V1_2::implementation::PreparedModelCallback;
 
 // internal helper function
 void createPreparedModel(const sp<IDevice>& device, const Model& model,
@@ -44,7 +42,7 @@
 
     // see if service can handle model
     bool fullySupportsModel = false;
-    const Return<void> supportedCall = device->getSupportedOperations_1_3(
+    const Return<void> supportedCall = device->getSupportedOperations_1_2(
             model, [&fullySupportsModel](ErrorStatus status, const hidl_vec<bool>& supported) {
                 ASSERT_EQ(ErrorStatus::NONE, status);
                 ASSERT_NE(0ul, supported.size());
@@ -55,7 +53,7 @@
 
     // launch prepare model
     const sp<PreparedModelCallback> preparedModelCallback = new PreparedModelCallback();
-    const Return<ErrorStatus> prepareLaunchStatus = device->prepareModel_1_3(
+    const Return<ErrorStatus> prepareLaunchStatus = device->prepareModel_1_2(
             model, ExecutionPreference::FAST_SINGLE_ANSWER, hidl_vec<hidl_handle>(),
             hidl_vec<hidl_handle>(), HidlToken(), preparedModelCallback);
     ASSERT_TRUE(prepareLaunchStatus.isOk());
@@ -66,8 +64,8 @@
     const ErrorStatus prepareReturnStatus = preparedModelCallback->getStatus();
     *preparedModel = getPreparedModel_1_2(preparedModelCallback);
 
-    // The getSupportedOperations_1_3 call returns a list of operations that are
-    // guaranteed not to fail if prepareModel_1_3 is called, and
+    // The getSupportedOperations_1_2 call returns a list of operations that are
+    // guaranteed not to fail if prepareModel_1_2 is called, and
     // 'fullySupportsModel' is true i.f.f. the entire model is guaranteed.
     // If a driver has any doubt that it can prepare an operation, it must
     // return false. So here, if a driver isn't sure if it can support an
@@ -165,9 +163,9 @@
 
 INSTANTIATE_GENERATED_TEST(ValidationTest, [](const test_helper::TestModel&) { return true; });
 
-sp<IPreparedModel> getPreparedModel_1_2(const sp<PreparedModelCallback>& callback) {
+sp<IPreparedModel> getPreparedModel_1_2(const sp<implementation::PreparedModelCallback>& callback) {
     sp<V1_0::IPreparedModel> preparedModelV1_0 = callback->getPreparedModel();
     return IPreparedModel::castFrom(preparedModelV1_0).withDefault(nullptr);
 }
 
-}  // namespace android::hardware::neuralnetworks::V1_3::vts::functional
+}  // namespace android::hardware::neuralnetworks::V1_2::vts::functional
diff --git a/neuralnetworks/1.3/vts/functional/VtsHalNeuralnetworks.h b/neuralnetworks/1.3/vts/functional/VtsHalNeuralnetworks.h
index fc654ce..d01336e 100644
--- a/neuralnetworks/1.3/vts/functional/VtsHalNeuralnetworks.h
+++ b/neuralnetworks/1.3/vts/functional/VtsHalNeuralnetworks.h
@@ -14,17 +14,17 @@
  * limitations under the License.
  */
 
-#ifndef ANDROID_HARDWARE_NEURALNETWORKS_V1_3_VTS_HAL_NEURALNETWORKS_H
-#define ANDROID_HARDWARE_NEURALNETWORKS_V1_3_VTS_HAL_NEURALNETWORKS_H
+#ifndef ANDROID_HARDWARE_NEURALNETWORKS_V1_2_VTS_HAL_NEURALNETWORKS_H
+#define ANDROID_HARDWARE_NEURALNETWORKS_V1_2_VTS_HAL_NEURALNETWORKS_H
 
+#include <android/hardware/neuralnetworks/1.2/IDevice.h>
 #include <android/hardware/neuralnetworks/1.2/IPreparedModel.h>
-#include <android/hardware/neuralnetworks/1.3/IDevice.h>
-#include <android/hardware/neuralnetworks/1.3/types.h>
+#include <android/hardware/neuralnetworks/1.2/types.h>
 #include <gtest/gtest.h>
 #include "1.0/Utils.h"
 #include "1.2/Callbacks.h"
 
-namespace android::hardware::neuralnetworks::V1_3::vts::functional {
+namespace android::hardware::neuralnetworks::V1_2::vts::functional {
 
 using NamedDevice = Named<sp<IDevice>>;
 using NeuralnetworksHidlTestParam = NamedDevice;
@@ -47,12 +47,11 @@
 // Create an IPreparedModel object. If the model cannot be prepared,
 // "preparedModel" will be nullptr instead.
 void createPreparedModel(const sp<IDevice>& device, const Model& model,
-                         sp<V1_2::IPreparedModel>* preparedModel);
+                         sp<IPreparedModel>* preparedModel);
 
 // Utility function to get PreparedModel from callback and downcast to V1_2.
-sp<V1_2::IPreparedModel> getPreparedModel_1_2(
-        const sp<V1_2::implementation::PreparedModelCallback>& callback);
+sp<IPreparedModel> getPreparedModel_1_2(const sp<implementation::PreparedModelCallback>& callback);
 
-}  // namespace android::hardware::neuralnetworks::V1_3::vts::functional
+}  // namespace android::hardware::neuralnetworks::V1_2::vts::functional
 
-#endif  // ANDROID_HARDWARE_NEURALNETWORKS_V1_3_VTS_HAL_NEURALNETWORKS_H
+#endif  // ANDROID_HARDWARE_NEURALNETWORKS_V1_2_VTS_HAL_NEURALNETWORKS_H
diff --git a/neuralnetworks/1.3/vts/functional/include/1.2/Callbacks.h b/neuralnetworks/1.3/vts/functional/include/1.2/Callbacks.h
new file mode 100644
index 0000000..bf4792c
--- /dev/null
+++ b/neuralnetworks/1.3/vts/functional/include/1.2/Callbacks.h
@@ -0,0 +1,325 @@
+/*
+ * Copyright (C) 2018 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.
+ */
+
+#ifndef ANDROID_HARDWARE_NEURALNETWORKS_V1_2_CALLBACKS_H
+#define ANDROID_HARDWARE_NEURALNETWORKS_V1_2_CALLBACKS_H
+
+#include <android-base/thread_annotations.h>
+#include <android/hardware/neuralnetworks/1.0/IExecutionCallback.h>
+#include <android/hardware/neuralnetworks/1.0/IPreparedModelCallback.h>
+#include <android/hardware/neuralnetworks/1.2/IExecutionCallback.h>
+#include <android/hardware/neuralnetworks/1.2/IPreparedModelCallback.h>
+#include <hidl/Status.h>
+#include <condition_variable>
+#include <mutex>
+
+/*
+ * The Callback classes are used internally by the NeuralNetworks runtime to
+ * synchronize between different threads. An asynchronous task is launched
+ * paired with a callback object. When a client thread requires the output being
+ * generated by the asynchronous task, the client thread can wait for the result
+ * and be blocked until it has completed. Any wait may safely be called
+ * concurrently, even on the same callback object. When the asynchronous task
+ * has finished its workload, it must immediately call "notify*". If the
+ * asynchronous task has failed to launch, the function that tried to launch the
+ * asynchronous task must immediately call "notify*". This "notify*" call
+ * awakens any client threads waiting on the callback object.
+ *
+ * These classes exist to enable synchronization across HIDL. When
+ * synchronization is only required in the same process, consider using
+ * std::future, std::mutex, std::condition_variable, or std::experimental::latch
+ * instead.
+ */
+
+namespace android::hardware::neuralnetworks::V1_2::implementation {
+
+/**
+ * The PreparedModelCallback class is used to receive the error status of
+ * preparing a model as well as the prepared model from a task executing
+ * asynchronously with respect to the runtime. If a calling thread calls wait
+ * or get* on a PreparedModelCallback object and the corresponding asynchronous
+ * task has not finished preparing the model, the calling thread will block
+ * until the asynchronous task has either called notify or notify_1_2.
+ *
+ * If the callback object is notified more than once, only the results of the
+ * first call to notify* are used, and the results from subsequent calls are
+ * discarded.
+ *
+ * This callback object is passed as an argument to IDevice::prepareModel*.
+ */
+class PreparedModelCallback : public IPreparedModelCallback {
+  public:
+    /**
+     * IPreparedModelCallback::notify marks the callback object with the return
+     * status of the asynchronous model preparation along with the prepared
+     * model, and allows all prior and future wait calls on the
+     * PreparedModelCallback object to proceed.
+     *
+     * Either IPreparedModelCallback::notify or
+     * IPreparedModelCallback::notify_1_2 must be called on a given
+     * PreparedModelCallback object.
+     *
+     * If the callback object is notified more than once, only the results of
+     * the first call to notify* are used, and the results from subsequent calls
+     * are discarded.
+     *
+     * @param status Error status returned from asynchronously preparing the
+     *     model; will be:
+     *     - NONE if the asynchronous preparation was successful
+     *     - DEVICE_UNAVAILABLE if driver is offline or busy
+     *     - GENERAL_FAILURE if there is an unspecified error
+     *     - INVALID_ARGUMENT if the input model is invalid
+     * @param preparedModel Returned model that has been prepared for execution,
+     *     nullptr if the model was unable to be prepared.
+     */
+    Return<void> notify(V1_0::ErrorStatus status,
+                        const sp<V1_0::IPreparedModel>& preparedModel) override;
+
+    /**
+     * IPreparedModelCallback::notify_1_2 marks the callback object with the
+     * return status of the asynchronous model preparation along with the
+     * prepared model, and allows all prior and future wait calls on the
+     * PreparedModelCallback object to proceed.
+     *
+     * Either IPreparedModelCallback::notify or
+     * IPreparedModelCallback::notify_1_2 must be called on a given
+     * PreparedModelCallback object.
+     *
+     * If the callback object is notified more than once, only the results of
+     * the first call to notify* are used, and the results from subsequent calls
+     * are discarded.
+     *
+     * @param status Error status returned from asynchronously preparing the
+     *     model; will be:
+     *     - NONE if the asynchronous preparation was successful
+     *     - DEVICE_UNAVAILABLE if driver is offline or busy
+     *     - GENERAL_FAILURE if there is an unspecified error
+     *     - INVALID_ARGUMENT if the input model is invalid
+     * @param preparedModel Returned model that has been prepared for execution,
+     *     nullptr if the model was unable to be prepared.
+     */
+    Return<void> notify_1_2(V1_0::ErrorStatus status,
+                            const sp<V1_2::IPreparedModel>& preparedModel) override;
+
+    /**
+     * PreparedModelCallback::wait blocks until notify* has been called on the
+     * callback object.
+     */
+    void wait() const;
+
+    /**
+     * Retrieves the error status returned from the asynchronous task launched
+     * by IDevice::prepareModel*. If IDevice::prepareModel* has not finished
+     * asynchronously preparing the model, this call will block until the
+     * asynchronous task notifies the object.
+     *
+     * @return status Error status returned from asynchronously preparing the
+     *     model; will be:
+     *     - NONE if the asynchronous preparation was successful
+     *     - DEVICE_UNAVAILABLE if driver is offline or busy
+     *     - GENERAL_FAILURE if there is an unspecified error
+     *     - INVALID_ARGUMENT if the input model is invalid
+     */
+    V1_0::ErrorStatus getStatus() const;
+
+    /**
+     * Retrieves the model that has been prepared for execution from the
+     * asynchronous task launched by IDevice::prepareModel*. If
+     * IDevice::prepareModel* has not finished asynchronously preparing the
+     * model, this call will block until the asynchronous task notifies the
+     * object.
+     *
+     * @return preparedModel Returned model that has been prepared for
+     *     execution, nullptr if the model was unable to be prepared.
+     */
+    sp<V1_0::IPreparedModel> getPreparedModel() const;
+
+  private:
+    mutable std::mutex mMutex;
+    mutable std::condition_variable mCondition;
+    bool mNotified GUARDED_BY(mMutex) = false;
+    V1_0::ErrorStatus mErrorStatus = V1_0::ErrorStatus::GENERAL_FAILURE;
+    sp<V1_0::IPreparedModel> mPreparedModel;
+};
+
+/**
+ * The ExecutionCallback class is used to receive the results of the execution
+ * from a task executing asynchronously with respect to the runtime. If a
+ * calling thread calls wait or get* on a ExecutionCallback object and the
+ * corresponding asynchronous task has not finished the execution, the calling
+ * thread will block until the asynchronous task has either called notify or
+ * notify_1_2.
+ *
+ * If the callback object is notified more than once, only the results of the
+ * first call to notify* are used, and the results from subsequent calls are
+ * discarded.
+ *
+ * This callback object is passed as an argument to IPreparedModel::execute*.
+ */
+class ExecutionCallback : public IExecutionCallback {
+  public:
+    /**
+     * IExecutionCallback::notify marks the callback object with the return
+     * status of the asynchronous execution that held this callback and enables
+     * all prior and future wait calls on the ExecutionCallback object to
+     * proceed.
+     *
+     * Either IExecutionCallback::notify or IExecutionCallback::notify_1_2 must
+     * be called on a given ExecutionCallback object.
+     *
+     * If the callback object is notified more than once, only the results of
+     * the first call to notify* are used, and the results from subsequent calls
+     * are discarded.
+     *
+     * @param status Error status returned from launching the asynchronous task
+     *     (if the launch fails) or from the asynchronous task itself (if the
+     *     launch succeeds). Must be:
+     *     - NONE if the asynchronous execution was successful
+     *     - DEVICE_UNAVAILABLE if driver is offline or busy
+     *     - GENERAL_FAILURE if there is an unspecified error
+     *     - OUTPUT_INSUFFICIENT_SIZE if provided output buffer is not large
+     *         enough to store the resultant values
+     *     - INVALID_ARGUMENT if the input request is invalid
+     */
+    Return<void> notify(V1_0::ErrorStatus status) override;
+
+    /**
+     * IExecutionCallback::notify_1_2 marks the callback object with the results
+     * (error status, dynamic output shapes, and timing information) of the
+     * asynchronous execution that held this callback and enables all prior and
+     * future wait calls on the ExecutionCallback object to proceed.
+     *
+     * Either IExecutionCallback::notify or IExecutionCallback::notify_1_2 must
+     * be called on a given ExecutionCallback object.
+     *
+     * If the callback object is notified more than once, only the results of
+     * the first call to notify* are used, and the results from subsequent calls
+     * are discarded.
+     *
+     * @param status Error status returned from launching the asynchronous task
+     *     (if the launch fails) or from the asynchronous task itself (if the
+     *     launch succeeds). Must be:
+     *     - NONE if the asynchronous execution was successful
+     *     - DEVICE_UNAVAILABLE if driver is offline or busy
+     *     - GENERAL_FAILURE if the asynchronous task resulted in an unspecified
+     *         error
+     *     - OUTPUT_INSUFFICIENT_SIZE if at least one output operand buffer is
+     *         not large enough to store the corresponding output
+     *     - INVALID_ARGUMENT if one of the input arguments to prepareModel is
+     *         invalid
+     * @param outputShapes A list of shape information of model output operands.
+     *     The index into "outputShapes" corresponds to the index of the output
+     *     operand in the Request outputs vector. outputShapes must be empty
+     *     unless the status is either NONE or OUTPUT_INSUFFICIENT_SIZE.
+     * @param Timing Duration of execution. Unless MeasureTiming::YES was passed
+     *     when launching the execution and status is NONE, all times must be
+     *     reported as UINT64_MAX. A driver may choose to report any time as
+     *     UINT64_MAX, indicating that particular measurement is not available.
+     */
+    Return<void> notify_1_2(V1_0::ErrorStatus status, const hidl_vec<OutputShape>& outputShapes,
+                            const Timing& timing) override;
+
+    // An overload of the latest notify interface to hide the version from ExecutionBuilder.
+    Return<void> notify(V1_0::ErrorStatus status, const hidl_vec<OutputShape>& outputShapes,
+                        const Timing& timing) {
+        return notify_1_2(status, outputShapes, timing);
+    }
+
+    /**
+     * ExecutionCallback::wait blocks until notify* has been called on the
+     * callback object.
+     */
+    void wait() const;
+
+    /**
+     * Retrieves the error status returned from the asynchronous task launched
+     * by either IPreparedModel::execute or IPreparedModel::execute_1_2. If
+     * IPreparedModel::execute or IPreparedModel::execute_1_2 has not finished
+     * asynchronously executing, this call will block until the asynchronous
+     * task notifies the object.
+     *
+     * @return status Error status returned from launching the asynchronous task
+     *     (if the launch fails) or from the asynchronous task itself (if the
+     *     launch succeeds). Must be:
+     *     - NONE if the asynchronous execution was successful
+     *     - DEVICE_UNAVAILABLE if driver is offline or busy
+     *     - GENERAL_FAILURE if the asynchronous task resulted in an unspecified
+     *         error
+     *     - OUTPUT_INSUFFICIENT_SIZE if at least one output operand buffer is
+     *         not large enough to store the corresponding output
+     *     - INVALID_ARGUMENT if one of the input arguments to prepareModel is
+     *         invalid
+     */
+    V1_0::ErrorStatus getStatus() const;
+
+    /**
+     * Retrieves the output shapes returned from the asynchronous task launched
+     * by IPreparedModel::execute_1_2. If IPreparedModel::execute_1_2 has not
+     * finished asynchronously executing, this call will block until the
+     * asynchronous task notifies the object.
+     *
+     * If the asynchronous task was launched by IPreparedModel::execute, an
+     * empty vector will be returned.
+     *
+     * @return outputShapes A list of shape information of model output
+     *     operands. The index into "outputShapes" corresponds to the index of
+     *     the output operand in the Request outputs vector. outputShapes must
+     *     be empty unless the status is either NONE or
+     *     OUTPUT_INSUFFICIENT_SIZE. outputShaps may be empty if the status is
+     *     NONE and all model output operands are fully-specified at execution
+     *     time. outputShapes must have the same number of elements as the
+     *     number of model output operands if the status is
+     *     OUTPUT_INSUFFICIENT_SIZE, or if the status is NONE and the model has
+     *     at least one output operand that is not fully-specified.
+     */
+    const std::vector<OutputShape>& getOutputShapes() const;
+
+    /**
+     * Retrieves the duration of execution of the asynchronous task launched by
+     * IPreparedModel::execute_1_2. If IPreparedModel::execute_1_2 has not
+     * finished asynchronously executing, this call will block until the
+     * asynchronous task notifies the object.
+     *
+     * If the asynchronous task was launched by IPreparedModel::execute, every
+     * time must be UINT64_MAX.
+     *
+     * @return timing Duration of the execution. Every time must be UINT64_MAX
+     *     unless the status is NONE.
+     */
+    Timing getTiming() const;
+
+  private:
+    /*
+     * ExecutionCallback::notifyInternal stores the results of the execution
+     * (status, output shapes, and timing information) in the ExecutionCallback
+     * object before any call to wait or get* return. It then enables all prior
+     * and future wait calls on the ExecutionCallback object to proceed.
+     */
+    void notifyInternal(V1_0::ErrorStatus errorStatus, const hidl_vec<OutputShape>& outputShapes,
+                        const Timing& timing);
+
+    // members
+    mutable std::mutex mMutex;
+    mutable std::condition_variable mCondition;
+    bool mNotified GUARDED_BY(mMutex) = false;
+    V1_0::ErrorStatus mErrorStatus = V1_0::ErrorStatus::GENERAL_FAILURE;
+    std::vector<OutputShape> mOutputShapes = {};
+    Timing mTiming = {};
+};
+
+}  // namespace android::hardware::neuralnetworks::V1_2::implementation
+
+#endif  // ANDROID_HARDWARE_NEURALNETWORKS_V1_2_CALLBACKS_H