diff --git a/audio/7.0/IDevice.hal b/audio/7.0/IDevice.hal
index e30e545..d9e0ad2 100644
--- a/audio/7.0/IDevice.hal
+++ b/audio/7.0/IDevice.hal
@@ -103,6 +103,11 @@
      * If the stream can not be opened with the proposed audio config,
      * HAL must provide suggested values for the audio config.
      *
+     * Note: INVALID_ARGUMENTS is returned both in the case when the
+     * HAL can not use the provided config and in the case when
+     * the value of any argument is invalid. In the latter case the
+     * HAL must provide a default initialized suggested config.
+     *
      * @param ioHandle handle assigned by AudioFlinger.
      * @param device device type and (if needed) address.
      * @param config stream configuration.
@@ -111,7 +116,8 @@
                              May be used by implementations to configure hardware effects.
      * @return retval operation completion status.
      * @return outStream created output stream.
-     * @return suggestedConfig in case of invalid parameters, suggested config.
+     * @return suggestedConfig in the case of rejection of the proposed config,
+     *                         a config suggested by the HAL.
      */
     openOutputStream(
             AudioIoHandle ioHandle,
@@ -128,6 +134,11 @@
      * If the stream can not be opened with the proposed audio config,
      * HAL must provide suggested values for the audio config.
      *
+     * Note: INVALID_ARGUMENTS is returned both in the case when the
+     * HAL can not use the provided config and in the case when
+     * the value of any argument is invalid. In the latter case the
+     * HAL must provide a default initialized suggested config.
+     *
      * @param ioHandle handle assigned by AudioFlinger.
      * @param device device type and (if needed) address.
      * @param config stream configuration.
@@ -136,7 +147,8 @@
      *                     May be used by implementations to configure processing effects.
      * @return retval operation completion status.
      * @return inStream in case of success, created input stream.
-     * @return suggestedConfig in case of invalid parameters, suggested config.
+     * @return suggestedConfig in the case of rejection of the proposed config,
+     *                         a config suggested by the HAL.
      */
     openInputStream(
             AudioIoHandle ioHandle,
diff --git a/audio/7.0/IStreamIn.hal b/audio/7.0/IStreamIn.hal
index 0a3f24b..bf9ae52 100644
--- a/audio/7.0/IStreamIn.hal
+++ b/audio/7.0/IStreamIn.hal
@@ -41,6 +41,18 @@
     setGain(float gain) generates (Result retval);
 
     /**
+     * Called when the metadata of the stream's sink has been changed.
+     * Optional method
+     *
+     * @param sinkMetadata Description of the audio that is suggested by the clients.
+     * @return retval operation completion status.
+     *        If any of the metadata fields contains an invalid value,
+     *        returns INVALID_ARGUMENTS.
+     *        If method isn't supported by the HAL returns NOT_SUPPORTED.
+     */
+    updateSinkMetadata(SinkMetadata sinkMetadata) generates (Result retval);
+
+    /**
      * Commands that can be executed on the driver reader thread.
      */
     enum ReadCommand : int32_t {
@@ -82,12 +94,6 @@
     };
 
     /**
-     * Called when the metadata of the stream's sink has been changed.
-     * @param sinkMetadata Description of the audio that is suggested by the clients.
-     */
-    updateSinkMetadata(SinkMetadata sinkMetadata);
-
-    /**
      * Set up required transports for receiving audio buffers from the driver.
      *
      * The transport consists of three message queues:
diff --git a/audio/7.0/IStreamOut.hal b/audio/7.0/IStreamOut.hal
index 38d750f..4daab26 100644
--- a/audio/7.0/IStreamOut.hal
+++ b/audio/7.0/IStreamOut.hal
@@ -45,6 +45,18 @@
     setVolume(float left, float right) generates (Result retval);
 
     /**
+     * Called when the metadata of the stream's source has been changed.
+     * Optional method
+     *
+     * @param sourceMetadata Description of the audio that is played by the clients.
+     * @return retval operation completion status.
+     *        If any of the metadata fields contains an invalid value,
+     *        returns INVALID_ARGUMENTS.
+     *        If method isn't supported by the HAL returns NOT_SUPPORTED.
+     */
+    updateSourceMetadata(SourceMetadata sourceMetadata) generates (Result retval);
+
+    /**
      * Commands that can be executed on the driver writer thread.
      */
     enum WriteCommand : int32_t {
@@ -77,12 +89,6 @@
     };
 
     /**
-     * Called when the metadata of the stream's source has been changed.
-     * @param sourceMetadata Description of the audio that is played by the clients.
-     */
-    updateSourceMetadata(SourceMetadata sourceMetadata);
-
-    /**
      * Set up required transports for passing audio buffers to the driver.
      *
      * The transport consists of three message queues: