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Groups > linux.kernel > #1514027

[mm PATCH v2 12/26] arch/metag: Add option to skip DMA sync as a part of 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
via a sync_for_cpu or sync_for_device call.

Cc: James Hogan <james.hogan@imgtec.com>
Cc: linux-metag@vger.kernel.org
Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
---
 arch/metag/kernel/dma.c |   16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/arch/metag/kernel/dma.c b/arch/metag/kernel/dma.c
index 0db31e2..91968d9 100644
--- 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);
 	}
 }

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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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