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dma-mapping: add a dma_alloc_need_uncached helper

Check if we need to allocate uncached memory for a device given the allocation flags. Switch over the uncached segment check to this helper to deal with architectures that do not support the dma_cache_sync operation and thus should not returned cacheable memory for DMA_ATTR_NON_CONSISTENT allocations.

Christoph Hellwig committed 7 years ago

Commit 4b85fae1 parent 961729b2 files · +16 −2Browse files

Showing the changes to include/linux (1 of 2 files). Show all

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include/linux/dma-noncoherent.h+14−0
@@ -20,6 +20,20 @@ static inline bool dev_is_dma_coherent(struct device *dev) · 19 unmodified lines
20}20}
21#endif /* CONFIG_ARCH_HAS_DMA_COHERENCE_H */21#endif /* CONFIG_ARCH_HAS_DMA_COHERENCE_H */
22 22
23/*
24 * Check if an allocation needs to be marked uncached to be coherent.
25 */
26static inline bool dma_alloc_need_uncached(struct device *dev,
27 unsigned long attrs)
28{
29 if (dev_is_dma_coherent(dev))
30 return false;
31 if (IS_ENABLED(CONFIG_DMA_NONCOHERENT_CACHE_SYNC) &&
32 (attrs & DMA_ATTR_NON_CONSISTENT))
33 return false;
34 return true;
35}
36
23void *arch_dma_alloc(struct device *dev, size_t size, dma_addr_t *dma_handle,37void *arch_dma_alloc(struct device *dev, size_t size, dma_addr_t *dma_handle,
24 gfp_t gfp, unsigned long attrs);38 gfp_t gfp, unsigned long attrs);
25void arch_dma_free(struct device *dev, size_t size, void *cpu_addr,39void arch_dma_free(struct device *dev, size_t size, void *cpu_addr,

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