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Diffstat (limited to 'arch/arm/mm/dma-mapping.c')
-rw-r--r--arch/arm/mm/dma-mapping.c15
1 files changed, 14 insertions, 1 deletions
diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
index 9e7742f0a102..c704eed63c5d 100644
--- a/arch/arm/mm/dma-mapping.c
+++ b/arch/arm/mm/dma-mapping.c
@@ -183,6 +183,8 @@ static void *
__dma_alloc_remap(struct page *page, size_t size, gfp_t gfp, pgprot_t prot)
{
struct arm_vmregion *c;
+ size_t align;
+ int bit;
if (!consistent_pte[0]) {
printk(KERN_ERR "%s: not initialised\n", __func__);
@@ -191,9 +193,20 @@ __dma_alloc_remap(struct page *page, size_t size, gfp_t gfp, pgprot_t prot)
}
/*
+ * Align the virtual region allocation - maximum alignment is
+ * a section size, minimum is a page size. This helps reduce
+ * fragmentation of the DMA space, and also prevents allocations
+ * smaller than a section from crossing a section boundary.
+ */
+ bit = fls(size - 1) + 1;
+ if (bit > SECTION_SHIFT)
+ bit = SECTION_SHIFT;
+ align = 1 << bit;
+
+ /*
* Allocate a virtual address in the consistent mapping region.
*/
- c = arm_vmregion_alloc(&consistent_head, size,
+ c = arm_vmregion_alloc(&consistent_head, align, size,
gfp & ~(__GFP_DMA | __GFP_HIGHMEM));
if (c) {
pte_t *pte;