arch/mips: add option to skip DMA sync as a part of map and unmap

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.

Link: http://lkml.kernel.org/r/20161110113513.76501.32321.stgit@ahduyck-blue-test.jf.intel.com
Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Keguang Zhang <keguang.zhang@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/arch/mips/loongson64/common/dma-swiotlb.c b/arch/mips/loongson64/common/dma-swiotlb.c
index 1a80b6f..aab4fd6 100644 (file)
--- a/arch/mips/loongson64/common/dma-swiotlb.c
+++ b/arch/mips/loongson64/common/dma-swiotlb.c
@@ -61,7 +61,7 @@ static int loongson_dma_map_sg(struct device *dev, struct scatterlist *sg,
                                int nents, enum dma_data_direction dir,
                                unsigned long attrs)
 {
-       int r = swiotlb_map_sg_attrs(dev, sg, nents, dir, 0);
+       int r = swiotlb_map_sg_attrs(dev, sg, nents, dir, attrs);
        mb();
 
        return r;

diff --git a/arch/mips/mm/dma-default.c b/arch/mips/mm/dma-default.c
index 46d5696..a39c36a 100644 (file)
--- a/arch/mips/mm/dma-default.c
+++ b/arch/mips/mm/dma-default.c
@@ -293,7 +293,7 @@ static inline void __dma_sync(struct page *page,
 static void mips_dma_unmap_page(struct device *dev, dma_addr_t dma_addr,
        size_t size, enum dma_data_direction direction, unsigned long attrs)
 {
-       if (cpu_needs_post_dma_flush(dev))
+       if (cpu_needs_post_dma_flush(dev) && !(attrs & DMA_ATTR_SKIP_CPU_SYNC))
                __dma_sync(dma_addr_to_page(dev, dma_addr),
                           dma_addr & ~PAGE_MASK, size, direction);
        plat_post_dma_flush(dev);
@@ -307,7 +307,8 @@ static int mips_dma_map_sg(struct device *dev, struct scatterlist *sglist,
        struct scatterlist *sg;
 
        for_each_sg(sglist, sg, nents, i) {
-               if (!plat_device_is_coherent(dev))
+               if (!plat_device_is_coherent(dev) &&
+                   !(attrs & DMA_ATTR_SKIP_CPU_SYNC))
                        __dma_sync(sg_page(sg), sg->offset, sg->length,
                                   direction);
 #ifdef CONFIG_NEED_SG_DMA_LENGTH
@@ -324,7 +325,7 @@ static dma_addr_t mips_dma_map_page(struct device *dev, struct page *page,
        unsigned long offset, size_t size, enum dma_data_direction direction,
        unsigned long attrs)
 {
-       if (!plat_device_is_coherent(dev))
+       if (!plat_device_is_coherent(dev) && !(attrs & DMA_ATTR_SKIP_CPU_SYNC))
                __dma_sync(page, offset, size, direction);
 
        return plat_map_dma_mem_page(dev, page) + offset;
@@ -339,6 +340,7 @@ static void mips_dma_unmap_sg(struct device *dev, struct scatterlist *sglist,
 
        for_each_sg(sglist, sg, nhwentries, i) {
                if (!plat_device_is_coherent(dev) &&
+                   !(attrs & DMA_ATTR_SKIP_CPU_SYNC) &&
                    direction != DMA_TO_DEVICE)
                        __dma_sync(sg_page(sg), sg->offset, sg->length,
                                   direction);