diff --git a/Documentation/sound/alsa/ALSA-Configuration.txt b/Documentation/sound/alsa/ALSA-Configuration.txt
index 1065bee..f947c4b 100644
--- a/Documentation/sound/alsa/ALSA-Configuration.txt
+++ b/Documentation/sound/alsa/ALSA-Configuration.txt
@@ -1411,6 +1411,9 @@
 
     vid             - Vendor ID for the device (optional)
     pid             - Product ID for the device (optional)
+    device_setup    - Device specific magic number (optional)
+                    - Influence depends on the device
+                    - Default: 0x0000 
 
     This module supports multiple devices, autoprobe and hotplugging.