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Diffstat (limited to 'arch/x86/mm/iomap_32.c')
-rw-r--r--arch/x86/mm/iomap_32.c12
1 files changed, 6 insertions, 6 deletions
diff --git a/arch/x86/mm/iomap_32.c b/arch/x86/mm/iomap_32.c
index 2b7ece0e103a..9c0ff045fdd4 100644
--- a/arch/x86/mm/iomap_32.c
+++ b/arch/x86/mm/iomap_32.c
@@ -78,13 +78,13 @@ void __iomem *
iomap_atomic_prot_pfn(unsigned long pfn, pgprot_t prot)
{
/*
- * For non-PAT systems, promote PAGE_KERNEL_WC to PAGE_KERNEL_UC_MINUS.
- * PAGE_KERNEL_WC maps to PWT, which translates to uncached if the
- * MTRR is UC or WC. UC_MINUS gets the real intention, of the
- * user, which is "WC if the MTRR is WC, UC if you can't do that."
+ * For non-PAT systems, translate non-WB request to UC- just in
+ * case the caller set the PWT bit to prot directly without using
+ * pgprot_writecombine(). UC- translates to uncached if the MTRR
+ * is UC or WC. UC- gets the real intention, of the user, which is
+ * "WC if the MTRR is WC, UC if you can't do that."
*/
- if (!pat_enabled && pgprot_val(prot) ==
- (__PAGE_KERNEL | cachemode2protval(_PAGE_CACHE_MODE_WC)))
+ if (!pat_enabled() && pgprot2cachemode(prot) != _PAGE_CACHE_MODE_WB)
prot = __pgprot(__PAGE_KERNEL |
cachemode2protval(_PAGE_CACHE_MODE_UC_MINUS));