arch/metag: add option to skip DMA sync as a part of map and unmap

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/20161110113503.76501.80809.stgit@ahduyck-blue-test.jf.intel.com
Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Cc: James Hogan <james.hogan@imgtec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/arch/metag/kernel/dma.c b/arch/metag/kernel/dma.c
index 0db31e24c541881aefc18e08b01764bd6c91a146..91968d92652b4a7f03fb9c7138d5685f569bcb64 100644 (file)
--- a/arch/metag/kernel/dma.c
+++ b/arch/metag/kernel/dma.c
@@ -484,8 +484,9 @@ static dma_addr_t metag_dma_map_page(struct device *dev, struct page *page,
                unsigned long offset, size_t size,
                enum dma_data_direction direction, unsigned long attrs)
 {
-       dma_sync_for_device((void *)(page_to_phys(page) + offset), size,
-                           direction);
+       if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC))
+               dma_sync_for_device((void *)(page_to_phys(page) + offset),
+                                   size, direction);
        return page_to_phys(page) + offset;
 }
 
@@ -493,7 +494,8 @@ static void metag_dma_unmap_page(struct device *dev, dma_addr_t dma_address,
                size_t size, enum dma_data_direction direction,
                unsigned long attrs)
 {
-       dma_sync_for_cpu(phys_to_virt(dma_address), size, direction);
+       if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC))
+               dma_sync_for_cpu(phys_to_virt(dma_address), size, direction);
 }
 
 static int metag_dma_map_sg(struct device *dev, struct scatterlist *sglist,
@@ -507,6 +509,10 @@ static int metag_dma_map_sg(struct device *dev, struct scatterlist *sglist,
                BUG_ON(!sg_page(sg));
 
                sg->dma_address = sg_phys(sg);
+
+               if (attrs & DMA_ATTR_SKIP_CPU_SYNC)
+                       continue;
+
                dma_sync_for_device(sg_virt(sg), sg->length, direction);
        }
 
@@ -525,6 +531,10 @@ static void metag_dma_unmap_sg(struct device *dev, struct scatterlist *sglist,
                BUG_ON(!sg_page(sg));
 
                sg->dma_address = sg_phys(sg);
+
+               if (attrs & DMA_ATTR_SKIP_CPU_SYNC)
+                       continue;
+
                dma_sync_for_cpu(sg_virt(sg), sg->length, direction);
        }
 }