[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: Russell King <rmk+kernel@arm.linux.org.uk>
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@ -376,11 +376,7 @@ static inline void dma_sync_single_range_for_cpu(struct device *dev,
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{
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BUG_ON(!valid_dma_direction(dir));
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if (!dmabounce_sync_for_cpu(dev, handle, offset, size, dir))
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return;
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if (!arch_is_coherent())
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dma_cache_maint(dma_to_virt(dev, handle) + offset, size, dir);
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dmabounce_sync_for_cpu(dev, handle, offset, size, dir);
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}
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static inline void dma_sync_single_range_for_device(struct device *dev,
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@ -585,12 +585,8 @@ void dma_sync_sg_for_cpu(struct device *dev, struct scatterlist *sg,
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int i;
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for_each_sg(sg, s, nents, i) {
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if (!dmabounce_sync_for_cpu(dev, sg_dma_address(s), 0,
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sg_dma_len(s), dir))
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continue;
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if (!arch_is_coherent())
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dma_cache_maint(sg_virt(s), s->length, dir);
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dmabounce_sync_for_cpu(dev, sg_dma_address(s), 0,
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sg_dma_len(s), dir);
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}
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}
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EXPORT_SYMBOL(dma_sync_sg_for_cpu);
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