diff --git a/neuralnetworks/1.2/IPreparedModelCallback.hal b/neuralnetworks/1.2/IPreparedModelCallback.hal
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+++ b/neuralnetworks/1.2/IPreparedModelCallback.hal
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+/*
+ * 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.
+ */
+
+package android.hardware.neuralnetworks@1.2;
+
+import @1.0::ErrorStatus;
+import @1.0::IPreparedModelCallback;
+import IPreparedModel;
+
+/**
+ * IPreparedModelCallback must be used to return a prepared model produced by an
+ * asynchronous task launched from IDevice::prepareModel.
+ */
+interface IPreparedModelCallback extends @1.0::IPreparedModelCallback {
+
+    /**
+     * Either notify_1_2 or notify must be invoked immediately after the asynchronous
+     * task holding this callback has finished preparing the model. If the model was
+     * successfully prepared, either notify_1_2 or notify must be invoked with
+     * ErrorStatus::NONE and the prepared model. If the model was not able to be
+     * successfully prepared, either notify_1_2 or notify must be invoked with the
+     * appropriate ErrorStatus and nullptr as the IPreparedModel. If the asynchronous
+     * task holding this callback fails to launch or if the model provided to
+     * IDevice::prepareModel is invalid, either notify_1_2 or notify must be invoked
+     * with the appropriate error as well as nullptr for the IPreparedModel.
+     *
+     * @param status Error status returned from the asynchronous model
+     *               preparation task; must be:
+     *               - NONE if the asynchronous task successfully prepared the
+     *                 model
+     *               - DEVICE_UNAVAILABLE if driver is offline or busy
+     *               - GENERAL_FAILURE if the asynchronous task resulted in an
+     *                 unspecified error
+     *               - INVALID_ARGUMENT if one of the input arguments to
+     *                 prepareModel is invalid
+     * @param preparedModel A model that has been asynchronously prepared for
+     *                      execution. If the model was unable to be prepared
+     *                      due to an error, nullptr must be passed in place of
+     *                      the IPreparedModel object.
+     */
+    oneway notify_1_2(ErrorStatus status, IPreparedModel preparedModel);
+};