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Groups > linux.kernel > #1514028

[mm PATCH v2 08/26] arch/c6x: Add option to skip sync on DMA map and unmap

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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.

Acked-by: Mark Salter <msalter@redhat.com>
Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
---
 arch/c6x/kernel/dma.c |   14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/arch/c6x/kernel/dma.c b/arch/c6x/kernel/dma.c
index db4a6a3..6752df3 100644
--- a/arch/c6x/kernel/dma.c
+++ b/arch/c6x/kernel/dma.c
@@ -42,14 +42,17 @@ static dma_addr_t c6x_dma_map_page(struct device *dev, struct page *page,
 {
 	dma_addr_t handle = virt_to_phys(page_address(page) + offset);
 
-	c6x_dma_sync(handle, size, dir);
+	if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC))
+		c6x_dma_sync(handle, size, dir);
+
 	return handle;
 }
 
 static void c6x_dma_unmap_page(struct device *dev, dma_addr_t handle,
 		size_t size, enum dma_data_direction dir, unsigned long attrs)
 {
-	c6x_dma_sync(handle, size, dir);
+	if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC))
+		c6x_dma_sync(handle, size, dir);
 }
 
 static int c6x_dma_map_sg(struct device *dev, struct scatterlist *sglist,
@@ -60,7 +63,8 @@ static int c6x_dma_map_sg(struct device *dev, struct scatterlist *sglist,
 
 	for_each_sg(sglist, sg, nents, i) {
 		sg->dma_address = sg_phys(sg);
-		c6x_dma_sync(sg->dma_address, sg->length, dir);
+		if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC))
+			c6x_dma_sync(sg->dma_address, sg->length, dir);
 	}
 
 	return nents;
@@ -72,9 +76,11 @@ static void c6x_dma_unmap_sg(struct device *dev, struct scatterlist *sglist,
 	struct scatterlist *sg;
 	int i;
 
+	if (attrs & DMA_ATTR_SKIP_CPU_SYNC)
+		return;
+
 	for_each_sg(sglist, sg, nents, i)
 		c6x_dma_sync(sg_dma_address(sg), sg->length, dir);
-
 }
 
 static void c6x_dma_sync_single_for_cpu(struct device *dev, dma_addr_t handle,

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[mm PATCH v2 00/26] Add support for DMA writable pages being  writable by the network stack Alexander Duyck <alexander.h.duyck@intel.com> - 2016-11-02 18:20 +0100
  [mm PATCH v2 01/26] swiotlb: Drop unused functions swiotlb_map_sg  and swiotlb_unmap_sg Alexander Duyck <alexander.h.duyck@intel.com> - 2016-11-02 18:20 +0100
    Re: [mm PATCH v2 01/26] swiotlb: Drop unused functions  swiotlb_map_sg and swiotlb_unmap_sg Christoph Hellwig <hch@infradead.org> - 2016-11-03 15:20 +0100
      Re: [mm PATCH v2 01/26] swiotlb: Drop unused functions  swiotlb_map_sg and swiotlb_unmap_sg Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> - 2016-11-03 15:40 +0100
        Re: [mm PATCH v2 01/26] swiotlb: Drop unused functions  swiotlb_map_sg and swiotlb_unmap_sg Christoph Hellwig <hch@infradead.org> - 2016-11-03 15:50 +0100
          RE: [mm PATCH v2 01/26] swiotlb: Drop unused functions  swiotlb_map_sg and swiotlb_unmap_sg "Duyck, Alexander H" <alexander.h.duyck@intel.com> - 2016-11-03 16:10 +0100
  [mm PATCH v2 06/26] arch/avr32: Add option to skip sync on DMA map Alexander Duyck <alexander.h.duyck@intel.com> - 2016-11-02 18:20 +0100
  [mm PATCH v2 23/26] dma: Add calls for dma_map_page_attrs and  dma_unmap_page_attrs Alexander Duyck <alexander.h.duyck@intel.com> - 2016-11-02 18:20 +0100
  [mm PATCH v2 21/26] arch/tile: Add option to skip DMA sync as a  part of map and unmap Alexander Duyck <alexander.h.duyck@intel.com> - 2016-11-02 18:20 +0100
  [mm PATCH v2 04/26] arch/arc: Add option to skip sync on DMA mapping Alexander Duyck <alexander.h.duyck@intel.com> - 2016-11-02 18:20 +0100
  [mm PATCH v2 09/26] arch/frv: Add option to skip sync on DMA map Alexander Duyck <alexander.h.duyck@intel.com> - 2016-11-02 18:20 +0100
  [mm PATCH v2 26/26] igb: Update code to better handle incrementing  page count Alexander Duyck <alexander.h.duyck@intel.com> - 2016-11-02 18:20 +0100
  [mm PATCH v2 12/26] arch/metag: Add option to skip DMA sync as a  part of map and unmap Alexander Duyck <alexander.h.duyck@intel.com> - 2016-11-02 18:20 +0100
  [mm PATCH v2 08/26] arch/c6x: Add option to skip sync on DMA map  and unmap Alexander Duyck <alexander.h.duyck@intel.com> - 2016-11-02 18:20 +0100
  [mm PATCH v2 24/26] mm: Add support for releasing multiple  instances of a page Alexander Duyck <alexander.h.duyck@intel.com> - 2016-11-02 18:20 +0100
  [mm PATCH v2 16/26] arch/openrisc: Add option to skip DMA sync as a  part of mapping Alexander Duyck <alexander.h.duyck@intel.com> - 2016-11-02 18:20 +0100
  [mm PATCH v2 13/26] arch/microblaze: Add option to skip DMA sync as  a part of map and unmap Alexander Duyck <alexander.h.duyck@intel.com> - 2016-11-02 18:30 +0100

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