Commit 4b85faed authored by Christoph Hellwig's avatar Christoph Hellwig
Browse files

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.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
parent 961729bf

include/linux/dma-noncoherent.h

+14 −0
Original line number Diff line number Diff line
@@ -20,6 +20,20 @@ static inline bool dev_is_dma_coherent(struct device *dev) 
}

#endif /* CONFIG_ARCH_HAS_DMA_COHERENCE_H */



/*

 * Check if an allocation needs to be marked uncached to be coherent.

 */

static inline bool dma_alloc_need_uncached(struct device *dev,

		unsigned long attrs)

{

	if (dev_is_dma_coherent(dev))

		return false;

	if (IS_ENABLED(CONFIG_DMA_NONCOHERENT_CACHE_SYNC) &&

	    (attrs & DMA_ATTR_NON_CONSISTENT))

		return false;

	return true;

}



void *arch_dma_alloc(struct device *dev, size_t size, dma_addr_t *dma_handle,

		gfp_t gfp, unsigned long attrs);

void arch_dma_free(struct device *dev, size_t size, void *cpu_addr,

kernel/dma/direct.c

+2 −2
Original line number Diff line number Diff line
@@ -160,7 +160,7 @@ void *dma_direct_alloc_pages(struct device *dev, size_t size, 
	memset(ret, 0, size);



	if (IS_ENABLED(CONFIG_ARCH_HAS_UNCACHED_SEGMENT) &&

	    !dev_is_dma_coherent(dev) && !(attrs & DMA_ATTR_NON_CONSISTENT)) {

	    dma_alloc_need_uncached(dev, attrs)) {

		arch_dma_prep_coherent(page, size);

		ret = uncached_kernel_address(ret);

	}
@@ -182,7 +182,7 @@ void dma_direct_free_pages(struct device *dev, size_t size, void *cpu_addr, 
		set_memory_encrypted((unsigned long)cpu_addr, 1 << page_order);



	if (IS_ENABLED(CONFIG_ARCH_HAS_UNCACHED_SEGMENT) &&

	    !dev_is_dma_coherent(dev) && !(attrs & DMA_ATTR_NON_CONSISTENT))

	    dma_alloc_need_uncached(dev, attrs))

		cpu_addr = cached_kernel_address(cpu_addr);

	__dma_direct_free_pages(dev, size, virt_to_page(cpu_addr));

}

CRA Git | Maintained and supported by SUSTech CRA and CCSE