diff --git a/arch/sh/boards/renesas/r7780rp/io.c b/arch/sh/boards/renesas/r7780rp/io.c
index 311ccccba718c48e7665403b6b1b722732c9a339..369cbf1cd471a51b2b02fd3ad01ebb9d3c59aaee 100644
--- a/arch/sh/boards/renesas/r7780rp/io.c
+++ b/arch/sh/boards/renesas/r7780rp/io.c
@@ -214,6 +214,8 @@ void r7780rp_insw(unsigned long port, void *dst, unsigned long count)
 
 	while (count--)
 		*buf++ = *p;
+
+	flush_dcache_all();
 }
 
 void r7780rp_insl(unsigned long port, void *dst, unsigned long count)
@@ -271,6 +273,8 @@ void r7780rp_outsw(unsigned long port, const void *src, unsigned long count)
 
 	while (count--)
 		*p = *buf++;
+
+	flush_dcache_all();
 }
 
 void r7780rp_outsl(unsigned long port, const void *src, unsigned long count)