ARM: 6870/1: The mandatory barrier rmb() must be a dsb() in for device accesses

Since mandatory barriers may be used (explicitly or implicitly via readl
etc.) to ensure the ordering between Device and Normal memory accesses,
a DMB is not enough. This patch converts it to a DSB.

Cc: Colin Cross <ccross@android.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

arch/arm/include/asm/system.h

@@ -159,7 +159,7 @@ extern unsigned int user_debug;
 #include <mach/barriers.h>
 #elif defined(CONFIG_ARM_DMA_MEM_BUFFERABLE) || defined(CONFIG_SMP)
 #define mb()		do { dsb(); outer_sync(); } while (0)
-#define rmb()		dmb()
+#define rmb()		dsb()
 #define wmb()		mb()
 #else
 #include <asm/memory.h>

arch/arm/mach-realview/include/mach/barriers.h

@@ -4,5 +4,5 @@
  * operation to deadlock the system.
  */
 #define mb()		dsb()
-#define rmb()		dmb()
+#define rmb()		dsb()
 #define wmb()		mb()

arch/arm/mach-tegra/include/mach/barriers.h

@@ -23,7 +23,7 @@
 
 #include <asm/outercache.h>
 
-#define rmb()		dmb()
+#define rmb()		dsb()
 #define wmb()		do { dsb(); outer_sync(); } while (0)
 #define mb()		wmb()