x86: gart alloc_coherent does virtual mapppings only when necessary

gart alloc_coherent need to do virtual mapppings only when an
allocated buffer is not DMA-capable for a device.

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Acked-by: Joerg Roedel <joerg.roedel@amd.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 9 insertions, 1 deletions

diff --git a/arch/x86/kernel/pci-gart_64.c b/arch/x86/kernel/pci-gart_64.c
index 9972c42ac925..9739d5682093 100644
--- a/arch/x86/kernel/pci-gart_64.c
+++ b/arch/x86/kernel/pci-gart_64.c
@@ -505,15 +505,23 @@ gart_alloc_coherent(struct device *dev, size_t size, dma_addr_t *dma_addr,
                     gfp_t flag)
 {
         void *vaddr;
+        dma_addr_t paddr;
         unsigned long align_mask;
+        u64 dma_mask = dma_alloc_coherent_mask(dev, flag);
 
         vaddr = (void *)__get_free_pages(flag | __GFP_ZERO, get_order(size));
         if (!vaddr)
                 return NULL;
 
+        paddr = virt_to_phys(vaddr);
+        if (is_buffer_dma_capable(dma_mask, paddr, size)) {
+                *dma_addr = paddr;
+                return vaddr;
+        }
+
         align_mask = (1UL << get_order(size)) - 1;
 
-        *dma_addr = dma_map_area(dev, __pa(vaddr), size, DMA_BIDIRECTIONAL,
+        *dma_addr = dma_map_area(dev, paddr, size, DMA_BIDIRECTIONAL,
                                  align_mask, dma_mask);
         flush_gart();