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Groups > linux.kernel > #1514022

[mm PATCH v2 21/26] arch/tile: 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: Chris Metcalf <cmetcalf@mellanox.com>
Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
---
 arch/tile/kernel/pci-dma.c |   12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/arch/tile/kernel/pci-dma.c b/arch/tile/kernel/pci-dma.c
index 09bb774..24e0f8c 100644
--- a/arch/tile/kernel/pci-dma.c
+++ b/arch/tile/kernel/pci-dma.c
@@ -213,10 +213,12 @@ static int tile_dma_map_sg(struct device *dev, struct scatterlist *sglist,
 
 	for_each_sg(sglist, sg, nents, i) {
 		sg->dma_address = sg_phys(sg);
-		__dma_prep_pa_range(sg->dma_address, sg->length, direction);
 #ifdef CONFIG_NEED_SG_DMA_LENGTH
 		sg->dma_length = sg->length;
 #endif
+		if (attrs & DMA_ATTR_SKIP_CPU_SYNC)
+			continue;
+		__dma_prep_pa_range(sg->dma_address, sg->length, direction);
 	}
 
 	return nents;
@@ -232,6 +234,8 @@ static void tile_dma_unmap_sg(struct device *dev, struct scatterlist *sglist,
 	BUG_ON(!valid_dma_direction(direction));
 	for_each_sg(sglist, sg, nents, i) {
 		sg->dma_address = sg_phys(sg);
+		if (attrs & DMA_ATTR_SKIP_CPU_SYNC)
+			continue;
 		__dma_complete_pa_range(sg->dma_address, sg->length,
 					direction);
 	}
@@ -245,7 +249,8 @@ static dma_addr_t tile_dma_map_page(struct device *dev, struct page *page,
 	BUG_ON(!valid_dma_direction(direction));
 
 	BUG_ON(offset + size > PAGE_SIZE);
-	__dma_prep_page(page, offset, size, direction);
+	if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC))
+		__dma_prep_page(page, offset, size, direction);
 
 	return page_to_pa(page) + offset;
 }
@@ -256,6 +261,9 @@ static void tile_dma_unmap_page(struct device *dev, dma_addr_t dma_address,
 {
 	BUG_ON(!valid_dma_direction(direction));
 
+	if (attrs & DMA_ATTR_SKIP_CPU_SYNC)
+		return;
+
 	__dma_complete_page(pfn_to_page(PFN_DOWN(dma_address)),
 			    dma_address & (PAGE_SIZE - 1), size, 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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