arch/sh: add option to skip DMA sync as a part of mapping

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/20161110113539.76501.6539.stgit@ahduyck-blue-test.jf.intel.com
Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Rich Felker <dalias@libc.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/arch/sh/kernel/dma-nommu.c b/arch/sh/kernel/dma-nommu.c
index eadb669a7329bf62785c733ab3cab0be73314c70..47fee3b6e29c1311ac2f36779ff5560c8d98cb28 100644 (file)
--- a/arch/sh/kernel/dma-nommu.c
+++ b/arch/sh/kernel/dma-nommu.c
@@ -18,7 +18,9 @@ static dma_addr_t nommu_map_page(struct device *dev, struct page *page,
        dma_addr_t addr = page_to_phys(page) + offset;
 
        WARN_ON(size == 0);
-       dma_cache_sync(dev, page_address(page) + offset, size, dir);
+
+       if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC))
+               dma_cache_sync(dev, page_address(page) + offset, size, dir);
 
        return addr;
 }
@@ -35,7 +37,8 @@ static int nommu_map_sg(struct device *dev, struct scatterlist *sg,
        for_each_sg(sg, s, nents, i) {
                BUG_ON(!sg_page(s));
 
-               dma_cache_sync(dev, sg_virt(s), s->length, dir);
+               if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC))
+                       dma_cache_sync(dev, sg_virt(s), s->length, dir);
 
                s->dma_address = sg_phys(s);
                s->dma_length = s->length;