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Subject[net-next PATCH 12/27] 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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