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Subject[net-next PATCH 08/27] 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.

Cc: Mark Salter <msalter@redhat.com>
Cc: Aurelien Jacquiot <a-jacquiot@ti.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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