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Commit 309dbbab authored by Russell King's avatar Russell King Committed by Russell King
Browse files

[ARM] dma: don't touch cache on dma_*_for_cpu() 



As per the dma_unmap_* calls, we don't touch the cache when a DMA
buffer transitions from device to CPU ownership.  Presently, no
problems have been identified with speculative cache prefetching
which in itself is a new feature in later architectures.  We may
have to revisit the DMA API later for these architectures anyway.

Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent 0e18b5d7

arch/arm/include/asm/dma-mapping.h

+1 −5
Original line number Diff line number Diff line
@@ -376,11 +376,7 @@ static inline void dma_sync_single_range_for_cpu(struct device *dev, 
{

	BUG_ON(!valid_dma_direction(dir));



	if (!dmabounce_sync_for_cpu(dev, handle, offset, size, dir))

		return;



	if (!arch_is_coherent())

		dma_cache_maint(dma_to_virt(dev, handle) + offset, size, dir);

	dmabounce_sync_for_cpu(dev, handle, offset, size, dir);

}



static inline void dma_sync_single_range_for_device(struct device *dev,

arch/arm/mm/dma-mapping.c

+2 −6
Original line number Diff line number Diff line
@@ -585,12 +585,8 @@ void dma_sync_sg_for_cpu(struct device *dev, struct scatterlist *sg, 
	int i;



	for_each_sg(sg, s, nents, i) {

		if (!dmabounce_sync_for_cpu(dev, sg_dma_address(s), 0,

					sg_dma_len(s), dir))

			continue;



		if (!arch_is_coherent())

			dma_cache_maint(sg_virt(s), s->length, dir);

		dmabounce_sync_for_cpu(dev, sg_dma_address(s), 0,

					sg_dma_len(s), dir);

	}

}

EXPORT_SYMBOL(dma_sync_sg_for_cpu);