diff --git a/Documentation/sound/alsa/ALSA-Configuration.txt b/Documentation/sound/alsa/ALSA-Configuration.txt
index 68bbc25..b33e030 100644
--- a/Documentation/sound/alsa/ALSA-Configuration.txt
+++ b/Documentation/sound/alsa/ALSA-Configuration.txt
@@ -1983,6 +1983,8 @@
     device_setup    - Device specific magic number (optional)
                     - Influence depends on the device
                     - Default: 0x0000 
+    ignore_ctl_error - Ignore any USB-controller regarding mixer
+    		       interface (default: no)
 
     This module supports multiple devices, autoprobe and hotplugging.
 
@@ -1991,6 +1993,9 @@
 	check.
     NB: async_unlink=0 would cause Oops.  It remains just for
         debugging purpose (if any).
+    NB: ignore_ctl_error=1 may help when you get an error at accessing
+        the mixer element such as URB error -22.  This happens on some
+        buggy USB device or the controller.
 
   Module snd-usb-caiaq
   --------------------