ARM: dma-mapping: switch ARMv7 DMA mappings to retain 'memory' attribute

On ARMv7, it is invalid to map the same physical address multiple times
with different memory types.  Since system RAM is already mapped as
'memory', subsequent remapping of it must retain this attribute.

However, DMA memory maps it as "strongly ordered".  Fix this by introducing
'pgprot_dmacoherent()' which provides the necessary page table bits for
DMA mappings.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Acked-by: Greg Ungerer <gerg@uclinux.org>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>

1 files changed, 2 insertions, 2 deletions

diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
index 6fac793329c6..26325cb5d368 100644
--- a/arch/arm/mm/dma-mapping.c
+++ b/arch/arm/mm/dma-mapping.c
@@ -317,7 +317,7 @@ dma_alloc_coherent(struct device *dev, size_t size, dma_addr_t *handle, gfp_t gf
                 return memory;
 
         return __dma_alloc(dev, size, handle, gfp,
-                           pgprot_noncached(pgprot_kernel));
+                           pgprot_dmacoherent(pgprot_kernel));
 }
 EXPORT_SYMBOL(dma_alloc_coherent);
 
@@ -365,7 +365,7 @@ static int dma_mmap(struct device *dev, struct vm_area_struct *vma,
 int dma_mmap_coherent(struct device *dev, struct vm_area_struct *vma,
                       void *cpu_addr, dma_addr_t dma_addr, size_t size)
 {
-        vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
+        vma->vm_page_prot = pgprot_dmacoherent(vma->vm_page_prot);
         return dma_mmap(dev, vma, cpu_addr, dma_addr, size);
 }
 EXPORT_SYMBOL(dma_mmap_coherent);