diff --git a/media/bufferpool/aidl/aidl_api/android.hardware.media.bufferpool2/current/android/hardware/media/bufferpool2/IClientManager.aidl b/media/bufferpool/aidl/aidl_api/android.hardware.media.bufferpool2/current/android/hardware/media/bufferpool2/IClientManager.aidl
index 54896d4..5899a40 100644
--- a/media/bufferpool/aidl/aidl_api/android.hardware.media.bufferpool2/current/android/hardware/media/bufferpool2/IClientManager.aidl
+++ b/media/bufferpool/aidl/aidl_api/android.hardware.media.bufferpool2/current/android/hardware/media/bufferpool2/IClientManager.aidl
@@ -34,5 +34,10 @@
 package android.hardware.media.bufferpool2;
 @VintfStability
 interface IClientManager {
-  long registerSender(in android.hardware.media.bufferpool2.IAccessor bufferPool);
+  android.hardware.media.bufferpool2.IClientManager.Registration registerSender(in android.hardware.media.bufferpool2.IAccessor bufferPool);
+  @VintfStability
+  parcelable Registration {
+    long connectionId;
+    boolean isNew = true;
+  }
 }
diff --git a/media/bufferpool/aidl/aidl_api/android.hardware.media.bufferpool2/current/android/hardware/media/bufferpool2/IConnection.aidl b/media/bufferpool/aidl/aidl_api/android.hardware.media.bufferpool2/current/android/hardware/media/bufferpool2/IConnection.aidl
index 300fcba..844e920 100644
--- a/media/bufferpool/aidl/aidl_api/android.hardware.media.bufferpool2/current/android/hardware/media/bufferpool2/IConnection.aidl
+++ b/media/bufferpool/aidl/aidl_api/android.hardware.media.bufferpool2/current/android/hardware/media/bufferpool2/IConnection.aidl
@@ -35,12 +35,13 @@
 @VintfStability
 interface IConnection {
   android.hardware.media.bufferpool2.IConnection.FetchResult[] fetch(in android.hardware.media.bufferpool2.IConnection.FetchInfo[] fetchInfos);
+  void sync();
   parcelable FetchInfo {
     long transactionId;
     int bufferId;
   }
   union FetchResult {
     android.hardware.media.bufferpool2.Buffer buffer;
-    android.hardware.media.bufferpool2.ResultStatus failure;
+    int failure;
   }
 }
diff --git a/media/bufferpool/aidl/aidl_api/android.hardware.media.bufferpool2/current/android/hardware/media/bufferpool2/ResultStatus.aidl b/media/bufferpool/aidl/aidl_api/android.hardware.media.bufferpool2/current/android/hardware/media/bufferpool2/ResultStatus.aidl
index 7370998..4bc3889 100644
--- a/media/bufferpool/aidl/aidl_api/android.hardware.media.bufferpool2/current/android/hardware/media/bufferpool2/ResultStatus.aidl
+++ b/media/bufferpool/aidl/aidl_api/android.hardware.media.bufferpool2/current/android/hardware/media/bufferpool2/ResultStatus.aidl
@@ -34,7 +34,6 @@
 package android.hardware.media.bufferpool2;
 @VintfStability
 parcelable ResultStatus {
-  int resultStatus;
   const int OK = 0;
   const int NO_MEMORY = 1;
   const int ALREADY_EXISTS = 2;
diff --git a/media/bufferpool/aidl/android/hardware/media/bufferpool2/IClientManager.aidl b/media/bufferpool/aidl/android/hardware/media/bufferpool2/IClientManager.aidl
index bf36e25..a3054cb 100644
--- a/media/bufferpool/aidl/android/hardware/media/bufferpool2/IClientManager.aidl
+++ b/media/bufferpool/aidl/android/hardware/media/bufferpool2/IClientManager.aidl
@@ -28,6 +28,16 @@
 @VintfStability
 interface IClientManager {
     /**
+     * Result of registerSender.
+     */
+    @VintfStability
+    parcelable Registration {
+        /** registered connection id    */
+        long connectionId;
+        /** true when the connection is new */
+        boolean isNew = true;
+    }
+    /**
      * Sets up a buffer receiving communication node for the specified
      * buffer pool. A manager must create a IConnection to the buffer
      * pool if it does not already have a connection.
@@ -39,8 +49,7 @@
      *     sent to that connection during transfers.
      * @throws ServiceSpecificException with one of the following values:
      *     ResultStatus::NO_MEMORY        - Memory allocation failure occurred.
-     *     ResultStatus::ALREADY_EXISTS   - A sender was registered already.
      *     ResultStatus::CRITICAL_ERROR   - Other errors.
      */
-    long registerSender(in IAccessor bufferPool);
+    Registration registerSender(in IAccessor bufferPool);
 }
diff --git a/media/bufferpool/aidl/android/hardware/media/bufferpool2/IConnection.aidl b/media/bufferpool/aidl/android/hardware/media/bufferpool2/IConnection.aidl
index d869f47..68367c7 100644
--- a/media/bufferpool/aidl/android/hardware/media/bufferpool2/IConnection.aidl
+++ b/media/bufferpool/aidl/android/hardware/media/bufferpool2/IConnection.aidl
@@ -49,7 +49,7 @@
          * ResultStatus::NOT_FOUND        - A buffer was not found due to invalidation.
          * ResultStatus::CRITICAL_ERROR   - Other errors.
          */
-        ResultStatus failure;
+        int failure;
     }
 
     /**
@@ -70,4 +70,12 @@
      *     ResultStatus::CRITICAL_ERROR   - Other errors.
      */
     FetchResult[] fetch(in FetchInfo[] fetchInfos);
+
+    /**
+     * Enforce processing of unprocessed bufferpool messages.
+     *
+     * BufferPool implementation optimizes message processing by piggy-backing approach.
+     * This method can ensure pending bufferpool messages being processed timely.
+     */
+    void sync();
 }
diff --git a/media/bufferpool/aidl/android/hardware/media/bufferpool2/ResultStatus.aidl b/media/bufferpool/aidl/android/hardware/media/bufferpool2/ResultStatus.aidl
index 162f9a7..003d147 100644
--- a/media/bufferpool/aidl/android/hardware/media/bufferpool2/ResultStatus.aidl
+++ b/media/bufferpool/aidl/android/hardware/media/bufferpool2/ResultStatus.aidl
@@ -23,6 +23,4 @@
     const int ALREADY_EXISTS = 2;
     const int NOT_FOUND = 3;
     const int CRITICAL_ERROR = 4;
-
-    int resultStatus;
 }