diff --git a/arch/nds32/include/asm/io.h b/arch/nds32/include/asm/io.h
index 71cd226d6863ee4a218e657dda216535f2e6fcf1..5ef8ae5ba83368af59be986582fb7e5f34a266f9 100644
--- a/arch/nds32/include/asm/io.h
+++ b/arch/nds32/include/asm/io.h
@@ -55,8 +55,6 @@ static inline u32 __raw_readl(const volatile void __iomem *addr)
 #define __iormb()               rmb()
 #define __iowmb()               wmb()
 
-#define mmiowb()        __asm__ __volatile__ ("msync all" : : : "memory");
-
 /*
  * {read,write}{b,w,l,q}_relaxed() are like the regular version, but
  * are not guaranteed to provide ordering against spinlocks or memory