diff --git a/Documentation/sound/alsa/ALSA-Configuration.txt b/Documentation/sound/alsa/ALSA-Configuration.txt
index 7134a8f..a763b76 100644
--- a/Documentation/sound/alsa/ALSA-Configuration.txt
+++ b/Documentation/sound/alsa/ALSA-Configuration.txt
@@ -609,6 +609,7 @@
     Module for ESS AudioDrive ES-1688 and ES-688 sound cards.
 
     port	- port # for ES-1688 chip (0x220,0x240,0x260)
+    fm_port	- port # for OPL3 (option; share the same port as default)
     mpu_port	- port # for MPU-401 port (0x300,0x310,0x320,0x330), -1 = disable (default)
     irq		- IRQ # for ES-1688 chip (5,7,9,10)
     mpu_irq	- IRQ # for MPU-401 port (5,7,9,10)