diff --git a/sound/soc/codecs/rt5640.h b/sound/soc/codecs/rt5640.h
index 90c8871..22c017c 100644
--- a/sound/soc/codecs/rt5640.h
+++ b/sound/soc/codecs/rt5640.h
@@ -1970,6 +1970,8 @@
 #define RT5640_ZCD_HP_DIS			(0x0 << 15)
 #define RT5640_ZCD_HP_EN			(0x1 << 15)
 
+/* General Control 1 (0xfa) */
+#define RT5640_MCLK_DET				(0x1 << 11)
 
 /* Codec Private Register definition */
 /* 3D Speaker Control (0x63) */