diff --git a/audio/7.0/IDevice.hal b/audio/7.0/IDevice.hal
index d9e0ad2..e423f29 100644
--- a/audio/7.0/IDevice.hal
+++ b/audio/7.0/IDevice.hal
@@ -174,6 +174,9 @@
      * Creates an audio patch between several source and sink ports.  The handle
      * is allocated by the HAL and must be unique for this audio HAL module.
      *
+     * Optional method. HAL must support it if 'supportsAudioPatches' returns
+     * 'true'.
+     *
      * @param sources patch sources.
      * @param sinks patch sinks.
      * @return retval operation completion status.
@@ -189,6 +192,9 @@
      * as the HAL module can figure out a way of switching the route without
      * causing audio disruption.
      *
+     * Optional method. HAL must support it if 'supportsAudioPatches' returns
+     * 'true'.
+     *
      * @param previousPatch handle of the previous patch to update.
      * @param sources new patch sources.
      * @param sinks new patch sinks.
@@ -204,6 +210,9 @@
     /**
      * Release an audio patch.
      *
+     * Optional method. HAL must support it if 'supportsAudioPatches' returns
+     * 'true'.
+     *
      * @param patch patch handle.
      * @return retval operation completion status.
      */