arch/xtensa: add option to skip DMA sync as a part of mapping

This change allows us to pass DMA_ATTR_SKIP_CPU_SYNC which allows us to
avoid invoking cache line invalidation if the driver will just handle it
via a sync_for_cpu or sync_for_device call.

Link: http://lkml.kernel.org/r/20161110113555.76501.52536.stgit@ahduyck-blue-test.jf.intel.com
Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/arch/xtensa/kernel/pci-dma.c b/arch/xtensa/kernel/pci-dma.c
index 1e68806d6695afc4a3fa21a8c7553fa38d5f885c..6a16decf278fa0a7dfa4dd5200e55a31258dace3 100644 (file)
--- a/arch/xtensa/kernel/pci-dma.c
+++ b/arch/xtensa/kernel/pci-dma.c
@@ -189,7 +189,9 @@ static dma_addr_t xtensa_map_page(struct device *dev, struct page *page,
 {
        dma_addr_t dma_handle = page_to_phys(page) + offset;
 
-       xtensa_sync_single_for_device(dev, dma_handle, size, dir);
+       if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC))
+               xtensa_sync_single_for_device(dev, dma_handle, size, dir);
+
        return dma_handle;
 }
 
@@ -197,7 +199,8 @@ static void xtensa_unmap_page(struct device *dev, dma_addr_t dma_handle,
                              size_t size, enum dma_data_direction dir,
                              unsigned long attrs)
 {
-       xtensa_sync_single_for_cpu(dev, dma_handle, size, dir);
+       if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC))
+               xtensa_sync_single_for_cpu(dev, dma_handle, size, dir);
 }
 
 static int xtensa_map_sg(struct device *dev, struct scatterlist *sg,