[PATCH 5/6] Use MTRR for write combining ioremap

[Thomas Schlichter]

If PAT is not enabled, set up write combining MTRR entries in ioremap().

Signed-off-by: Thomas Schlichter <thomas.schlichter@xxxxxx>
---
 arch/x86/mm/ioremap.c |   15 ++++++++++-----
 1 files changed, 10 insertions(+), 5 deletions(-)

diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
index 334e63c..abe40fa 100644
--- a/arch/x86/mm/ioremap.c
+++ b/arch/x86/mm/ioremap.c
@@ -21,6 +21,7 @@
 #include <asm/tlbflush.h>
 #include <asm/pgalloc.h>
 #include <asm/pat.h>
+#include <asm/mtrr.h>
 
 #include "physaddr.h"
 
@@ -268,11 +269,15 @@ EXPORT_SYMBOL(ioremap_nocache);
  */
 void __iomem *ioremap_wc(resource_size_t phys_addr, unsigned long size)
 {
-	if (pat_enabled)
-		return __ioremap_caller(phys_addr, size, _PAGE_CACHE_WC,
-					__builtin_return_address(0));
-	else
-		return ioremap_nocache(phys_addr, size);
+	if (!pat_enabled) {
+		void __iomem *ret = ioremap_nocache(phys_addr, size);
+		if (ret)
+			mtrr_add_unaligned(phys_addr, size,
+					   MTRR_TYPE_WRCOMB, false);
+		return ret;
+	}
+	return __ioremap_caller(phys_addr, size, _PAGE_CACHE_WC,
+				__builtin_return_address(0));
 }
 EXPORT_SYMBOL(ioremap_wc);
 
-- 
1.6.5


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