diff --git a/neuralnetworks/1.2/utils/include/nnapi/hal/1.2/Callbacks.h b/neuralnetworks/1.2/utils/include/nnapi/hal/1.2/Callbacks.h
index 1162bc3..ba3c1ba 100644
--- a/neuralnetworks/1.2/utils/include/nnapi/hal/1.2/Callbacks.h
+++ b/neuralnetworks/1.2/utils/include/nnapi/hal/1.2/Callbacks.h
@@ -36,6 +36,19 @@
 
 namespace android::hardware::neuralnetworks::V1_2::utils {
 
+// Converts the results of IDevice::prepareModel* to the NN canonical format. On success, this
+// function returns with a non-null nn::SharedPreparedModel with a feature level of
+// nn::Version::ANDROID_Q. On failure, this function returns with the appropriate nn::GeneralError.
+nn::GeneralResult<nn::SharedPreparedModel> prepareModelCallback(
+        V1_0::ErrorStatus status, const sp<IPreparedModel>& preparedModel);
+
+// Converts the results of IDevice::execute* to the NN canonical format. On success, this function
+// returns with the output shapes and the timing information. On failure, this function returns with
+// the appropriate nn::ExecutionError.
+nn::ExecutionResult<std::pair<std::vector<nn::OutputShape>, nn::Timing>> executionCallback(
+        V1_0::ErrorStatus status, const hidl_vec<OutputShape>& outputShapes, const Timing& timing);
+
+// A HIDL callback class to receive the results of IDevice::prepareModel* asynchronously.
 class PreparedModelCallback final : public IPreparedModelCallback,
                                     public hal::utils::IProtectedCallback {
   public:
@@ -51,11 +64,10 @@
     Data get();
 
   private:
-    void notifyInternal(Data result);
-
     hal::utils::TransferValue<Data> mData;
 };
 
+// A HIDL callback class to receive the results of IDevice::execute_1_2 asynchronously.
 class ExecutionCallback final : public IExecutionCallback, public hal::utils::IProtectedCallback {
   public:
     using Data = nn::ExecutionResult<std::pair<std::vector<nn::OutputShape>, nn::Timing>>;
@@ -69,8 +81,6 @@
     Data get();
 
   private:
-    void notifyInternal(Data result);
-
     hal::utils::TransferValue<Data> mData;
 };
 
diff --git a/neuralnetworks/1.2/utils/include/nnapi/hal/1.2/Conversions.h b/neuralnetworks/1.2/utils/include/nnapi/hal/1.2/Conversions.h
index 5dcbc0b..6fd1337 100644
--- a/neuralnetworks/1.2/utils/include/nnapi/hal/1.2/Conversions.h
+++ b/neuralnetworks/1.2/utils/include/nnapi/hal/1.2/Conversions.h
@@ -97,6 +97,12 @@
 nn::GeneralResult<hidl_vec<hidl_handle>> convert(const std::vector<nn::SharedHandle>& handles);
 nn::GeneralResult<hidl_vec<OutputShape>> convert(const std::vector<nn::OutputShape>& outputShapes);
 
+nn::GeneralResult<V1_0::DeviceStatus> convert(const nn::DeviceStatus& deviceStatus);
+nn::GeneralResult<V1_0::Request> convert(const nn::Request& request);
+nn::GeneralResult<V1_0::ErrorStatus> convert(const nn::ErrorStatus& status);
+nn::GeneralResult<V1_1::ExecutionPreference> convert(
+        const nn::ExecutionPreference& executionPreference);
+
 }  // namespace android::hardware::neuralnetworks::V1_2::utils
 
 #endif  // ANDROID_HARDWARE_INTERFACES_NEURALNETWORKS_1_2_CONVERSIONS_H
diff --git a/neuralnetworks/1.2/utils/include/nnapi/hal/1.2/Device.h b/neuralnetworks/1.2/utils/include/nnapi/hal/1.2/Device.h
index 79c3b04..b4bef5e 100644
--- a/neuralnetworks/1.2/utils/include/nnapi/hal/1.2/Device.h
+++ b/neuralnetworks/1.2/utils/include/nnapi/hal/1.2/Device.h
@@ -37,10 +37,21 @@
 
 namespace android::hardware::neuralnetworks::V1_2::utils {
 
-nn::GeneralResult<std::string> initVersionString(V1_2::IDevice* device);
-nn::GeneralResult<nn::DeviceType> initDeviceType(V1_2::IDevice* device);
-nn::GeneralResult<std::vector<nn::Extension>> initExtensions(V1_2::IDevice* device);
-nn::GeneralResult<std::pair<uint32_t, uint32_t>> initNumberOfCacheFilesNeeded(
+// Retrieves the version string from the provided device object. On failure, this function returns
+// with the appropriate nn::GeneralError.
+nn::GeneralResult<std::string> getVersionStringFrom(V1_2::IDevice* device);
+
+// Retrieves the device type from the provided device object. On failure, this function returns with
+// the appropriate nn::GeneralError.
+nn::GeneralResult<nn::DeviceType> getDeviceTypeFrom(V1_2::IDevice* device);
+
+// Retrieves the extensions supported by the provided device object. On failure, this function
+// returns with the appropriate nn::GeneralError.
+nn::GeneralResult<std::vector<nn::Extension>> getSupportedExtensionsFrom(V1_2::IDevice* device);
+
+// Retrieves the number of model cache files and data cache files needed by the provided device
+// object. On failure, this function returns with the appropriate nn::GeneralError.
+nn::GeneralResult<std::pair<uint32_t, uint32_t>> getNumberOfCacheFilesNeededFrom(
         V1_2::IDevice* device);
 
 // Class that adapts V1_2::IDevice to nn::IDevice.
diff --git a/neuralnetworks/1.2/utils/include/nnapi/hal/1.2/PreparedModel.h b/neuralnetworks/1.2/utils/include/nnapi/hal/1.2/PreparedModel.h
index 8ed5ca7..6a56a82 100644
--- a/neuralnetworks/1.2/utils/include/nnapi/hal/1.2/PreparedModel.h
+++ b/neuralnetworks/1.2/utils/include/nnapi/hal/1.2/PreparedModel.h
@@ -41,10 +41,10 @@
 
   public:
     static nn::GeneralResult<std::shared_ptr<const PreparedModel>> create(
-            sp<V1_2::IPreparedModel> preparedModel);
+            sp<V1_2::IPreparedModel> preparedModel, bool executeSynchronously);
 
-    PreparedModel(PrivateConstructorTag tag, sp<V1_2::IPreparedModel> preparedModel,
-                  hal::utils::DeathHandler deathHandler);
+    PreparedModel(PrivateConstructorTag tag, bool executeSynchronously,
+                  sp<V1_2::IPreparedModel> preparedModel, hal::utils::DeathHandler deathHandler);
 
     nn::ExecutionResult<std::pair<std::vector<nn::OutputShape>, nn::Timing>> execute(
             const nn::Request& request, nn::MeasureTiming measure,
@@ -65,6 +65,7 @@
     nn::ExecutionResult<std::pair<std::vector<nn::OutputShape>, nn::Timing>> executeAsynchronously(
             const V1_0::Request& request, MeasureTiming measure) const;
 
+    const bool kExecuteSynchronously;
     const sp<V1_2::IPreparedModel> kPreparedModel;
     const hal::utils::DeathHandler kDeathHandler;
 };
diff --git a/neuralnetworks/1.2/utils/include/nnapi/hal/1.2/Utils.h b/neuralnetworks/1.2/utils/include/nnapi/hal/1.2/Utils.h
index 70149a2..c289fc8 100644
--- a/neuralnetworks/1.2/utils/include/nnapi/hal/1.2/Utils.h
+++ b/neuralnetworks/1.2/utils/include/nnapi/hal/1.2/Utils.h
@@ -30,6 +30,8 @@
 
 namespace android::hardware::neuralnetworks::V1_2::utils {
 
+using CacheToken = hidl_array<uint8_t, static_cast<size_t>(Constant::BYTE_SIZE_OF_CACHE_TOKEN)>;
+
 constexpr auto kDefaultMesaureTiming = MeasureTiming::NO;
 constexpr auto kNoTiming = Timing{.timeOnDevice = std::numeric_limits<uint64_t>::max(),
                                   .timeInDriver = std::numeric_limits<uint64_t>::max()};
diff --git a/neuralnetworks/1.2/utils/src/Callbacks.cpp b/neuralnetworks/1.2/utils/src/Callbacks.cpp
index ab3e0ca..fefa122 100644
--- a/neuralnetworks/1.2/utils/src/Callbacks.cpp
+++ b/neuralnetworks/1.2/utils/src/Callbacks.cpp
@@ -27,6 +27,7 @@
 #include <nnapi/IPreparedModel.h>
 #include <nnapi/Result.h>
 #include <nnapi/Types.h>
+#include <nnapi/hal/1.0/Callbacks.h>
 #include <nnapi/hal/1.0/Conversions.h>
 #include <nnapi/hal/1.0/PreparedModel.h>
 #include <nnapi/hal/CommonUtils.h>
@@ -42,104 +43,73 @@
 namespace android::hardware::neuralnetworks::V1_2::utils {
 namespace {
 
-nn::GeneralResult<nn::SharedPreparedModel> convertPreparedModel(
-        const sp<V1_0::IPreparedModel>& preparedModel) {
-    return NN_TRY(V1_0::utils::PreparedModel::create(preparedModel));
-}
-
-nn::GeneralResult<nn::SharedPreparedModel> convertPreparedModel(
-        const sp<IPreparedModel>& preparedModel) {
-    return NN_TRY(utils::PreparedModel::create(preparedModel));
-}
-
 nn::GeneralResult<std::pair<std::vector<nn::OutputShape>, nn::Timing>>
 convertExecutionGeneralResultsHelper(const hidl_vec<OutputShape>& outputShapes,
                                      const Timing& timing) {
     return std::make_pair(NN_TRY(nn::convert(outputShapes)), NN_TRY(nn::convert(timing)));
 }
 
-nn::ExecutionResult<std::pair<std::vector<nn::OutputShape>, nn::Timing>>
-convertExecutionGeneralResults(const hidl_vec<OutputShape>& outputShapes, const Timing& timing) {
+}  // namespace
+
+nn::GeneralResult<nn::SharedPreparedModel> prepareModelCallback(
+        V1_0::ErrorStatus status, const sp<IPreparedModel>& preparedModel) {
+    HANDLE_HAL_STATUS(status) << "model preparation failed with " << toString(status);
+    return NN_TRY(PreparedModel::create(preparedModel, /*executeSynchronously=*/true));
+}
+
+nn::ExecutionResult<std::pair<std::vector<nn::OutputShape>, nn::Timing>> executionCallback(
+        V1_0::ErrorStatus status, const hidl_vec<OutputShape>& outputShapes, const Timing& timing) {
+    if (status == V1_0::ErrorStatus::OUTPUT_INSUFFICIENT_SIZE) {
+        auto canonicalOutputShapes =
+                nn::convert(outputShapes).value_or(std::vector<nn::OutputShape>{});
+        return NN_ERROR(nn::ErrorStatus::OUTPUT_INSUFFICIENT_SIZE, std::move(canonicalOutputShapes))
+               << "execution failed with " << toString(status);
+    }
+    HANDLE_HAL_STATUS(status) << "execution failed with " << toString(status);
     return hal::utils::makeExecutionFailure(
             convertExecutionGeneralResultsHelper(outputShapes, timing));
 }
 
-}  // namespace
-
 Return<void> PreparedModelCallback::notify(V1_0::ErrorStatus status,
                                            const sp<V1_0::IPreparedModel>& preparedModel) {
-    if (status != V1_0::ErrorStatus::NONE) {
-        const auto canonical = nn::convert(status).value_or(nn::ErrorStatus::GENERAL_FAILURE);
-        notifyInternal(NN_ERROR(canonical) << "preparedModel failed with " << toString(status));
-    } else if (preparedModel == nullptr) {
-        notifyInternal(NN_ERROR(nn::ErrorStatus::GENERAL_FAILURE)
-                       << "Returned preparedModel is nullptr");
-    } else {
-        notifyInternal(convertPreparedModel(preparedModel));
-    }
+    mData.put(V1_0::utils::prepareModelCallback(status, preparedModel));
     return Void();
 }
 
 Return<void> PreparedModelCallback::notify_1_2(V1_0::ErrorStatus status,
                                                const sp<IPreparedModel>& preparedModel) {
-    if (status != V1_0::ErrorStatus::NONE) {
-        const auto canonical = nn::convert(status).value_or(nn::ErrorStatus::GENERAL_FAILURE);
-        notifyInternal(NN_ERROR(canonical) << "preparedModel failed with " << toString(status));
-    } else if (preparedModel == nullptr) {
-        notifyInternal(NN_ERROR(nn::ErrorStatus::GENERAL_FAILURE)
-                       << "Returned preparedModel is nullptr");
-    } else {
-        notifyInternal(convertPreparedModel(preparedModel));
-    }
+    mData.put(prepareModelCallback(status, preparedModel));
     return Void();
 }
 
 void PreparedModelCallback::notifyAsDeadObject() {
-    notifyInternal(NN_ERROR(nn::ErrorStatus::DEAD_OBJECT) << "Dead object");
+    mData.put(NN_ERROR(nn::ErrorStatus::DEAD_OBJECT) << "Dead object");
 }
 
 PreparedModelCallback::Data PreparedModelCallback::get() {
     return mData.take();
 }
 
-void PreparedModelCallback::notifyInternal(PreparedModelCallback::Data result) {
-    mData.put(std::move(result));
-}
-
 // ExecutionCallback methods begin here
 
 Return<void> ExecutionCallback::notify(V1_0::ErrorStatus status) {
-    if (status != V1_0::ErrorStatus::NONE) {
-        const auto canonical = nn::convert(status).value_or(nn::ErrorStatus::GENERAL_FAILURE);
-        notifyInternal(NN_ERROR(canonical) << "execute failed with " << toString(status));
-    } else {
-        notifyInternal({});
-    }
+    mData.put(V1_0::utils::executionCallback(status));
     return Void();
 }
 
 Return<void> ExecutionCallback::notify_1_2(V1_0::ErrorStatus status,
                                            const hidl_vec<OutputShape>& outputShapes,
                                            const Timing& timing) {
-    if (status != V1_0::ErrorStatus::NONE) {
-        const auto canonical = nn::convert(status).value_or(nn::ErrorStatus::GENERAL_FAILURE);
-        notifyInternal(NN_ERROR(canonical) << "execute failed with " << toString(status));
-    } else {
-        notifyInternal(convertExecutionGeneralResults(outputShapes, timing));
-    }
+    mData.put(executionCallback(status, outputShapes, timing));
     return Void();
 }
 
 void ExecutionCallback::notifyAsDeadObject() {
-    notifyInternal(NN_ERROR(nn::ErrorStatus::DEAD_OBJECT) << "Dead object");
+    mData.put(NN_ERROR(nn::ErrorStatus::DEAD_OBJECT) << "Dead object");
 }
 
 ExecutionCallback::Data ExecutionCallback::get() {
     return mData.take();
 }
 
-void ExecutionCallback::notifyInternal(ExecutionCallback::Data result) {
-    mData.put(std::move(result));
-}
-
 }  // namespace android::hardware::neuralnetworks::V1_2::utils
diff --git a/neuralnetworks/1.2/utils/src/Conversions.cpp b/neuralnetworks/1.2/utils/src/Conversions.cpp
index 3790d1f..062f6f7 100644
--- a/neuralnetworks/1.2/utils/src/Conversions.cpp
+++ b/neuralnetworks/1.2/utils/src/Conversions.cpp
@@ -26,6 +26,7 @@
 #include <nnapi/Types.h>
 #include <nnapi/Validation.h>
 #include <nnapi/hal/1.0/Conversions.h>
+#include <nnapi/hal/1.1/Conversions.h>
 #include <nnapi/hal/CommonUtils.h>
 #include <nnapi/hal/HandleError.h>
 
@@ -622,4 +623,21 @@
     return validatedConvert(outputShapes);
 }
 
+nn::GeneralResult<V1_0::DeviceStatus> convert(const nn::DeviceStatus& deviceStatus) {
+    return V1_1::utils::convert(deviceStatus);
+}
+
+nn::GeneralResult<V1_0::Request> convert(const nn::Request& request) {
+    return V1_1::utils::convert(request);
+}
+
+nn::GeneralResult<V1_0::ErrorStatus> convert(const nn::ErrorStatus& status) {
+    return V1_1::utils::convert(status);
+}
+
+nn::GeneralResult<V1_1::ExecutionPreference> convert(
+        const nn::ExecutionPreference& executionPreference) {
+    return V1_1::utils::convert(executionPreference);
+}
+
 }  // namespace android::hardware::neuralnetworks::V1_2::utils
diff --git a/neuralnetworks/1.2/utils/src/Device.cpp b/neuralnetworks/1.2/utils/src/Device.cpp
index 6cca841..9fe0de2 100644
--- a/neuralnetworks/1.2/utils/src/Device.cpp
+++ b/neuralnetworks/1.2/utils/src/Device.cpp
@@ -47,109 +47,102 @@
 namespace android::hardware::neuralnetworks::V1_2::utils {
 namespace {
 
-nn::GeneralResult<nn::Capabilities> initCapabilities(V1_2::IDevice* device) {
+nn::GeneralResult<nn::Capabilities> capabilitiesCallback(V1_0::ErrorStatus status,
+                                                         const Capabilities& capabilities) {
+    HANDLE_HAL_STATUS(status) << "getting capabilities failed with " << toString(status);
+    return nn::convert(capabilities);
+}
+
+nn::GeneralResult<std::string> versionStringCallback(V1_0::ErrorStatus status,
+                                                     const hidl_string& versionString) {
+    HANDLE_HAL_STATUS(status) << "getVersionString failed with " << toString(status);
+    return versionString;
+}
+
+nn::GeneralResult<nn::DeviceType> deviceTypeCallback(V1_0::ErrorStatus status,
+                                                     DeviceType deviceType) {
+    HANDLE_HAL_STATUS(status) << "getDeviceType failed with " << toString(status);
+    return nn::convert(deviceType);
+}
+
+nn::GeneralResult<std::vector<nn::Extension>> supportedExtensionsCallback(
+        V1_0::ErrorStatus status, const hidl_vec<Extension>& extensions) {
+    HANDLE_HAL_STATUS(status) << "getExtensions failed with " << toString(status);
+    return nn::convert(extensions);
+}
+
+nn::GeneralResult<std::pair<uint32_t, uint32_t>> numberOfCacheFilesNeededCallback(
+        V1_0::ErrorStatus status, uint32_t numModelCache, uint32_t numDataCache) {
+    HANDLE_HAL_STATUS(status) << "getNumberOfCacheFilesNeeded failed with " << toString(status);
+    if (numModelCache > nn::kMaxNumberOfCacheFiles) {
+        return NN_ERROR() << "getNumberOfCacheFilesNeeded returned numModelCache files greater "
+                             "than allowed max ("
+                          << numModelCache << " vs " << nn::kMaxNumberOfCacheFiles << ")";
+    }
+    if (numDataCache > nn::kMaxNumberOfCacheFiles) {
+        return NN_ERROR() << "getNumberOfCacheFilesNeeded returned numDataCache files greater "
+                             "than allowed max ("
+                          << numDataCache << " vs " << nn::kMaxNumberOfCacheFiles << ")";
+    }
+    return std::make_pair(numModelCache, numDataCache);
+}
+
+nn::GeneralResult<nn::Capabilities> getCapabilitiesFrom(V1_2::IDevice* device) {
     CHECK(device != nullptr);
 
-    nn::GeneralResult<nn::Capabilities> result = NN_ERROR(nn::ErrorStatus::GENERAL_FAILURE)
-                                                 << "uninitialized";
-    const auto cb = [&result](V1_0::ErrorStatus status, const Capabilities& capabilities) {
-        if (status != V1_0::ErrorStatus::NONE) {
-            const auto canonical = nn::convert(status).value_or(nn::ErrorStatus::GENERAL_FAILURE);
-            result = NN_ERROR(canonical) << "getCapabilities_1_2 failed with " << toString(status);
-        } else {
-            result = nn::convert(capabilities);
-        }
-    };
+    auto cb = hal::utils::CallbackValue(capabilitiesCallback);
 
     const auto ret = device->getCapabilities_1_2(cb);
     HANDLE_TRANSPORT_FAILURE(ret);
 
-    return result;
+    return cb.take();
 }
 
 }  // namespace
 
-nn::GeneralResult<std::string> initVersionString(V1_2::IDevice* device) {
+nn::GeneralResult<std::string> getVersionStringFrom(V1_2::IDevice* device) {
     CHECK(device != nullptr);
 
-    nn::GeneralResult<std::string> result = NN_ERROR(nn::ErrorStatus::GENERAL_FAILURE)
-                                            << "uninitialized";
-    const auto cb = [&result](V1_0::ErrorStatus status, const hidl_string& versionString) {
-        if (status != V1_0::ErrorStatus::NONE) {
-            const auto canonical = nn::convert(status).value_or(nn::ErrorStatus::GENERAL_FAILURE);
-            result = NN_ERROR(canonical) << "getVersionString failed with " << toString(status);
-        } else {
-            result = versionString;
-        }
-    };
+    auto cb = hal::utils::CallbackValue(versionStringCallback);
 
     const auto ret = device->getVersionString(cb);
     HANDLE_TRANSPORT_FAILURE(ret);
 
-    return result;
+    return cb.take();
 }
 
-nn::GeneralResult<nn::DeviceType> initDeviceType(V1_2::IDevice* device) {
+nn::GeneralResult<nn::DeviceType> getDeviceTypeFrom(V1_2::IDevice* device) {
     CHECK(device != nullptr);
 
-    nn::GeneralResult<nn::DeviceType> result = NN_ERROR(nn::ErrorStatus::GENERAL_FAILURE)
-                                               << "uninitialized";
-    const auto cb = [&result](V1_0::ErrorStatus status, DeviceType deviceType) {
-        if (status != V1_0::ErrorStatus::NONE) {
-            const auto canonical = nn::convert(status).value_or(nn::ErrorStatus::GENERAL_FAILURE);
-            result = NN_ERROR(canonical) << "getDeviceType failed with " << toString(status);
-        } else {
-            result = nn::convert(deviceType);
-        }
-    };
+    auto cb = hal::utils::CallbackValue(deviceTypeCallback);
 
     const auto ret = device->getType(cb);
     HANDLE_TRANSPORT_FAILURE(ret);
 
-    return result;
+    return cb.take();
 }
 
-nn::GeneralResult<std::vector<nn::Extension>> initExtensions(V1_2::IDevice* device) {
+nn::GeneralResult<std::vector<nn::Extension>> getSupportedExtensionsFrom(V1_2::IDevice* device) {
     CHECK(device != nullptr);
 
-    nn::GeneralResult<std::vector<nn::Extension>> result =
-            NN_ERROR(nn::ErrorStatus::GENERAL_FAILURE) << "uninitialized";
-    const auto cb = [&result](V1_0::ErrorStatus status, const hidl_vec<Extension>& extensions) {
-        if (status != V1_0::ErrorStatus::NONE) {
-            const auto canonical = nn::convert(status).value_or(nn::ErrorStatus::GENERAL_FAILURE);
-            result = NN_ERROR(canonical) << "getExtensions failed with " << toString(status);
-        } else {
-            result = nn::convert(extensions);
-        }
-    };
+    auto cb = hal::utils::CallbackValue(supportedExtensionsCallback);
 
     const auto ret = device->getSupportedExtensions(cb);
     HANDLE_TRANSPORT_FAILURE(ret);
 
-    return result;
+    return cb.take();
 }
 
-nn::GeneralResult<std::pair<uint32_t, uint32_t>> initNumberOfCacheFilesNeeded(
+nn::GeneralResult<std::pair<uint32_t, uint32_t>> getNumberOfCacheFilesNeededFrom(
         V1_2::IDevice* device) {
     CHECK(device != nullptr);
 
-    nn::GeneralResult<std::pair<uint32_t, uint32_t>> result =
-            NN_ERROR(nn::ErrorStatus::GENERAL_FAILURE) << "uninitialized";
-    const auto cb = [&result](V1_0::ErrorStatus status, uint32_t numModelCache,
-                              uint32_t numDataCache) {
-        if (status != V1_0::ErrorStatus::NONE) {
-            const auto canonical = nn::convert(status).value_or(nn::ErrorStatus::GENERAL_FAILURE);
-            result = NN_ERROR(canonical)
-                     << "getNumberOfCacheFilesNeeded failed with " << toString(status);
-        } else {
-            result = std::make_pair(numModelCache, numDataCache);
-        }
-    };
+    auto cb = hal::utils::CallbackValue(numberOfCacheFilesNeededCallback);
 
     const auto ret = device->getNumberOfCacheFilesNeeded(cb);
     HANDLE_TRANSPORT_FAILURE(ret);
 
-    return result;
+    return cb.take();
 }
 
 nn::GeneralResult<std::shared_ptr<const Device>> Device::create(std::string name,
@@ -163,11 +156,11 @@
                << "V1_2::utils::Device::create must have non-null device";
     }
 
-    auto versionString = NN_TRY(initVersionString(device.get()));
-    const auto deviceType = NN_TRY(initDeviceType(device.get()));
-    auto extensions = NN_TRY(initExtensions(device.get()));
-    auto capabilities = NN_TRY(initCapabilities(device.get()));
-    const auto numberOfCacheFilesNeeded = NN_TRY(initNumberOfCacheFilesNeeded(device.get()));
+    auto versionString = NN_TRY(getVersionStringFrom(device.get()));
+    const auto deviceType = NN_TRY(getDeviceTypeFrom(device.get()));
+    auto extensions = NN_TRY(getSupportedExtensionsFrom(device.get()));
+    auto capabilities = NN_TRY(getCapabilitiesFrom(device.get()));
+    const auto numberOfCacheFilesNeeded = NN_TRY(getNumberOfCacheFilesNeededFrom(device.get()));
 
     auto deathHandler = NN_TRY(hal::utils::DeathHandler::create(device));
     return std::make_shared<const Device>(
@@ -232,28 +225,12 @@
 
     const auto hidlModel = NN_TRY(convert(modelInShared));
 
-    nn::GeneralResult<std::vector<bool>> result = NN_ERROR(nn::ErrorStatus::GENERAL_FAILURE)
-                                                  << "uninitialized";
-    auto cb = [&result, &model](V1_0::ErrorStatus status,
-                                const hidl_vec<bool>& supportedOperations) {
-        if (status != V1_0::ErrorStatus::NONE) {
-            const auto canonical = nn::convert(status).value_or(nn::ErrorStatus::GENERAL_FAILURE);
-            result = NN_ERROR(canonical)
-                     << "getSupportedOperations_1_2 failed with " << toString(status);
-        } else if (supportedOperations.size() != model.main.operations.size()) {
-            result = NN_ERROR(nn::ErrorStatus::GENERAL_FAILURE)
-                     << "getSupportedOperations_1_2 returned vector of size "
-                     << supportedOperations.size() << " but expected "
-                     << model.main.operations.size();
-        } else {
-            result = supportedOperations;
-        }
-    };
+    auto cb = hal::utils::CallbackValue(V1_0::utils::supportedOperationsCallback);
 
     const auto ret = kDevice->getSupportedOperations_1_2(hidlModel, cb);
     HANDLE_TRANSPORT_FAILURE(ret);
 
-    return result;
+    return cb.take();
 }
 
 nn::GeneralResult<nn::SharedPreparedModel> Device::prepareModel(
@@ -266,10 +243,10 @@
             NN_TRY(hal::utils::flushDataFromPointerToShared(&model, &maybeModelInShared));
 
     const auto hidlModel = NN_TRY(convert(modelInShared));
-    const auto hidlPreference = NN_TRY(V1_1::utils::convert(preference));
+    const auto hidlPreference = NN_TRY(convert(preference));
     const auto hidlModelCache = NN_TRY(convert(modelCache));
     const auto hidlDataCache = NN_TRY(convert(dataCache));
-    const auto hidlToken = token;
+    const auto hidlToken = CacheToken{token};
 
     const auto cb = sp<PreparedModelCallback>::make();
     const auto scoped = kDeathHandler.protectCallback(cb.get());
@@ -277,10 +254,7 @@
     const auto ret = kDevice->prepareModel_1_2(hidlModel, hidlPreference, hidlModelCache,
                                                hidlDataCache, hidlToken, cb);
     const auto status = HANDLE_TRANSPORT_FAILURE(ret);
-    if (status != V1_0::ErrorStatus::NONE) {
-        const auto canonical = nn::convert(status).value_or(nn::ErrorStatus::GENERAL_FAILURE);
-        return NN_ERROR(canonical) << "prepareModel_1_2 failed with " << toString(status);
-    }
+    HANDLE_HAL_STATUS(status) << "model preparation failed with " << toString(status);
 
     return cb->get();
 }
@@ -290,17 +264,14 @@
         const std::vector<nn::SharedHandle>& dataCache, const nn::CacheToken& token) const {
     const auto hidlModelCache = NN_TRY(convert(modelCache));
     const auto hidlDataCache = NN_TRY(convert(dataCache));
-    const auto hidlToken = token;
+    const auto hidlToken = CacheToken{token};
 
     const auto cb = sp<PreparedModelCallback>::make();
     const auto scoped = kDeathHandler.protectCallback(cb.get());
 
     const auto ret = kDevice->prepareModelFromCache(hidlModelCache, hidlDataCache, hidlToken, cb);
     const auto status = HANDLE_TRANSPORT_FAILURE(ret);
-    if (status != V1_0::ErrorStatus::NONE) {
-        const auto canonical = nn::convert(status).value_or(nn::ErrorStatus::GENERAL_FAILURE);
-        return NN_ERROR(canonical) << "prepareModelFromCache failed with " << toString(status);
-    }
+    HANDLE_HAL_STATUS(status) << "model preparation from cache failed with " << toString(status);
 
     return cb->get();
 }
diff --git a/neuralnetworks/1.2/utils/src/PreparedModel.cpp b/neuralnetworks/1.2/utils/src/PreparedModel.cpp
index b422ced..6d00082 100644
--- a/neuralnetworks/1.2/utils/src/PreparedModel.cpp
+++ b/neuralnetworks/1.2/utils/src/PreparedModel.cpp
@@ -41,54 +41,33 @@
 // lifetimes across processes and for protecting asynchronous calls across HIDL.
 
 namespace android::hardware::neuralnetworks::V1_2::utils {
-namespace {
-
-nn::GeneralResult<std::pair<std::vector<nn::OutputShape>, nn::Timing>>
-convertExecutionResultsHelper(const hidl_vec<OutputShape>& outputShapes, const Timing& timing) {
-    return std::make_pair(NN_TRY(nn::convert(outputShapes)), NN_TRY(nn::convert(timing)));
-}
-
-nn::ExecutionResult<std::pair<std::vector<nn::OutputShape>, nn::Timing>> convertExecutionResults(
-        const hidl_vec<OutputShape>& outputShapes, const Timing& timing) {
-    return hal::utils::makeExecutionFailure(convertExecutionResultsHelper(outputShapes, timing));
-}
-
-}  // namespace
 
 nn::GeneralResult<std::shared_ptr<const PreparedModel>> PreparedModel::create(
-        sp<V1_2::IPreparedModel> preparedModel) {
+        sp<V1_2::IPreparedModel> preparedModel, bool executeSynchronously) {
     if (preparedModel == nullptr) {
-        return NN_ERROR(nn::ErrorStatus::INVALID_ARGUMENT)
-               << "V1_2::utils::PreparedModel::create must have non-null preparedModel";
+        return NN_ERROR() << "V1_2::utils::PreparedModel::create must have non-null preparedModel";
     }
 
     auto deathHandler = NN_TRY(hal::utils::DeathHandler::create(preparedModel));
-    return std::make_shared<const PreparedModel>(PrivateConstructorTag{}, std::move(preparedModel),
-                                                 std::move(deathHandler));
+    return std::make_shared<const PreparedModel>(PrivateConstructorTag{}, executeSynchronously,
+                                                 std::move(preparedModel), std::move(deathHandler));
 }
 
-PreparedModel::PreparedModel(PrivateConstructorTag /*tag*/, sp<V1_2::IPreparedModel> preparedModel,
+PreparedModel::PreparedModel(PrivateConstructorTag /*tag*/, bool executeSynchronously,
+                             sp<V1_2::IPreparedModel> preparedModel,
                              hal::utils::DeathHandler deathHandler)
-    : kPreparedModel(std::move(preparedModel)), kDeathHandler(std::move(deathHandler)) {}
+    : kExecuteSynchronously(executeSynchronously),
+      kPreparedModel(std::move(preparedModel)),
+      kDeathHandler(std::move(deathHandler)) {}
 
 nn::ExecutionResult<std::pair<std::vector<nn::OutputShape>, nn::Timing>>
 PreparedModel::executeSynchronously(const V1_0::Request& request, MeasureTiming measure) const {
-    nn::ExecutionResult<std::pair<std::vector<nn::OutputShape>, nn::Timing>> result =
-            NN_ERROR(nn::ErrorStatus::GENERAL_FAILURE) << "uninitialized";
-    const auto cb = [&result](V1_0::ErrorStatus status, const hidl_vec<OutputShape>& outputShapes,
-                              const Timing& timing) {
-        if (status != V1_0::ErrorStatus::NONE) {
-            const auto canonical = nn::convert(status).value_or(nn::ErrorStatus::GENERAL_FAILURE);
-            result = NN_ERROR(canonical) << "executeSynchronously failed with " << toString(status);
-        } else {
-            result = convertExecutionResults(outputShapes, timing);
-        }
-    };
+    auto cb = hal::utils::CallbackValue(executionCallback);
 
     const auto ret = kPreparedModel->executeSynchronously(request, measure, cb);
     HANDLE_TRANSPORT_FAILURE(ret);
 
-    return result;
+    return cb.take();
 }
 
 nn::ExecutionResult<std::pair<std::vector<nn::OutputShape>, nn::Timing>>
@@ -98,9 +77,8 @@
 
     const auto ret = kPreparedModel->execute_1_2(request, measure, cb);
     const auto status = HANDLE_TRANSPORT_FAILURE(ret);
-    if (status != V1_0::ErrorStatus::NONE) {
-        const auto canonical = nn::convert(status).value_or(nn::ErrorStatus::GENERAL_FAILURE);
-        return NN_ERROR(canonical) << "execute failed with " << toString(status);
+    if (status != V1_0::ErrorStatus::OUTPUT_INSUFFICIENT_SIZE) {
+        HANDLE_HAL_STATUS(status) << "execution failed with " << toString(status);
     }
 
     return cb->get();
@@ -115,31 +93,17 @@
     const nn::Request& requestInShared = NN_TRY(hal::utils::makeExecutionFailure(
             hal::utils::flushDataFromPointerToShared(&request, &maybeRequestInShared)));
 
-    const auto hidlRequest =
-            NN_TRY(hal::utils::makeExecutionFailure(V1_0::utils::convert(requestInShared)));
+    const auto hidlRequest = NN_TRY(hal::utils::makeExecutionFailure(convert(requestInShared)));
     const auto hidlMeasure = NN_TRY(hal::utils::makeExecutionFailure(convert(measure)));
 
-    nn::ExecutionResult<std::pair<std::vector<nn::OutputShape>, nn::Timing>> result =
-            NN_ERROR(nn::ErrorStatus::GENERAL_FAILURE) << "uninitialized";
-    const bool preferSynchronous = true;
+    auto result = kExecuteSynchronously ? executeSynchronously(hidlRequest, hidlMeasure)
+                                        : executeAsynchronously(hidlRequest, hidlMeasure);
+    auto [outputShapes, timing] = NN_TRY(std::move(result));
 
-    // Execute synchronously if allowed.
-    if (preferSynchronous) {
-        result = executeSynchronously(hidlRequest, hidlMeasure);
-    }
+    NN_TRY(hal::utils::makeExecutionFailure(
+            hal::utils::unflushDataFromSharedToPointer(request, maybeRequestInShared)));
 
-    // Run asymchronous execution if execution has not already completed.
-    if (!result.has_value()) {
-        result = executeAsynchronously(hidlRequest, hidlMeasure);
-    }
-
-    // Flush output buffers if suxcessful execution.
-    if (result.has_value()) {
-        NN_TRY(hal::utils::makeExecutionFailure(
-                hal::utils::unflushDataFromSharedToPointer(request, maybeRequestInShared)));
-    }
-
-    return result;
+    return std::make_pair(std::move(outputShapes), timing);
 }
 
 nn::GeneralResult<std::pair<nn::SyncFence, nn::ExecuteFencedInfoCallback>>
@@ -154,7 +118,7 @@
 }
 
 std::any PreparedModel::getUnderlyingResource() const {
-    sp<V1_0::IPreparedModel> resource = kPreparedModel;
+    sp<V1_2::IPreparedModel> resource = kPreparedModel;
     return resource;
 }