diff --git a/ArmPkg/Drivers/MmCommunicationDxe/MmCommunication.c b/ArmPkg/Drivers/MmCommunicationDxe/MmCommunication.c
index 7c8284104d..7f756a32d4 100644
--- a/ArmPkg/Drivers/MmCommunicationDxe/MmCommunication.c
+++ b/ArmPkg/Drivers/MmCommunicationDxe/MmCommunication.c
@@ -41,12 +41,13 @@ STATIC EFI_HANDLE  mMmCommunicateHandle;
 
   This function provides a service to send and receive messages from a registered UEFI service.
 
-  @param[in] This                The EFI_MM_COMMUNICATION_PROTOCOL instance.
-  @param[in] CommBufferPhysical  Physical address of the MM communication buffer
-  @param[in] CommBufferVirtual   Virtual address of the MM communication buffer
-  @param[in] CommSize            The size of the data buffer being passed in. On exit, the size of data
-                                 being returned. Zero if the handler does not wish to reply with any data.
-                                 This parameter is optional and may be NULL.
+  @param[in] This                     The EFI_MM_COMMUNICATION_PROTOCOL instance.
+  @param[in, out] CommBufferPhysical  Physical address of the MM communication buffer
+  @param[in, out] CommBufferVirtual   Virtual address of the MM communication buffer
+  @param[in, out] CommSize            The size of the data buffer being passed in. On exit, the
+                                      size of data being returned. Zero if the handler does not
+                                      wish to reply with any data. This parameter is optional
+                                      and may be NULL.
 
   @retval EFI_SUCCESS            The message was successfully posted.
   @retval EFI_INVALID_PARAMETER  CommBufferPhysical was NULL or CommBufferVirtual was NULL.