diff --git a/arch/arm/mach-shmobile/board-ap4evb.c b/arch/arm/mach-shmobile/board-ap4evb.c
index 99ef190d0909d5ee5bf633efd0b660061244e71b..70d287c28a625f39081f23de73118a8d5801966b 100644
--- a/arch/arm/mach-shmobile/board-ap4evb.c
+++ b/arch/arm/mach-shmobile/board-ap4evb.c
@@ -143,6 +143,10 @@
  *
  * SW41	:  ON : SH-Mobile AP4 Audio Mode
  *	: OFF : Bluetooth Audio Mode
+ *
+ * it needs amixer settings for playing
+ *
+ * amixer set "Headphone Enable" on
  */
 
 /*