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>

diff --git a/arch/x86/kernel/pci-gart_64.c b/arch/x86/kernel/pci-gart_64.c
index 9972c42..9739d56 100644 (file)
--- 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();