diff --git a/Documentation/rapidio/mport_cdev.txt b/Documentation/rapidio/mport_cdev.txt
index 6e491a662461..a53f786ee2e9 100644
--- a/Documentation/rapidio/mport_cdev.txt
+++ b/Documentation/rapidio/mport_cdev.txt
@@ -80,6 +80,10 @@ functionality of their platform when planning to use this driver:
 
 III. Module parameters
 
+- 'dma_timeout' - DMA transfer completion timeout (in msec, default value 3000).
+        This parameter set a maximum completion wait time for SYNC mode DMA
+        transfer requests and for RIO_WAIT_FOR_ASYNC ioctl requests.
+
 - 'dbg_level' - This parameter allows to control amount of debug information
         generated by this device driver. This parameter is formed by set of
         bit masks that correspond to the specific functional blocks.