arch/hexagon: 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
later via a sync_for_cpu or sync_for_device call.

Link: http://lkml.kernel.org/r/20161110113452.76501.45864.stgit@ahduyck-blue-test.jf.intel.com
Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Cc: Richard Kuo <rkuo@codeaurora.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/arch/hexagon/kernel/dma.c b/arch/hexagon/kernel/dma.c
index b901778..dbc4f10 100644 (file)
--- a/arch/hexagon/kernel/dma.c
+++ b/arch/hexagon/kernel/dma.c
@@ -119,6 +119,9 @@ static int hexagon_map_sg(struct device *hwdev, struct scatterlist *sg,
 
                s->dma_length = s->length;
 
+               if (attrs & DMA_ATTR_SKIP_CPU_SYNC)
+                       continue;
+
                flush_dcache_range(dma_addr_to_virt(s->dma_address),
                                   dma_addr_to_virt(s->dma_address + s->length));
        }
@@ -180,7 +183,8 @@ static dma_addr_t hexagon_map_page(struct device *dev, struct page *page,
        if (!check_addr("map_single", dev, bus, size))
                return bad_dma_address;
 
-       dma_sync(dma_addr_to_virt(bus), size, dir);
+       if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC))
+               dma_sync(dma_addr_to_virt(bus), size, dir);
 
        return bus;
 }