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Commit 56f55f8b authored by Russell King's avatar Russell King Committed by Russell King
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[ARM] dma: provide a better dma_map_page() implementation 



We can translate a struct page directly to a DMA address using
page_to_dma().  No need to use page_address() followed by
virt_to_dma().

Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent afd1a321

arch/arm/common/dmabounce.c

+13 −0
Original line number Diff line number Diff line
@@ -412,6 +412,19 @@ dma_map_single(struct device *dev, void *ptr, size_t size, 
	return dma_addr;

}



dma_addr_t dma_map_page(struct device *dev, struct page *page,

			unsigned long offset, size_t size,

			enum dma_data_direction dir)

{

	dev_dbg(dev, "%s(page=%p,off=%#lx,size=%zx,dir=%x)\n",

		__func__, page, offset, size, dir);



	BUG_ON(dir == DMA_NONE);



	return map_single(dev, page_address(page) + offset, size, dir);

}

EXPORT_SYMBOL(dma_map_page);



/*

 * see if a mapped address was really a "safe" buffer and if so, copy

 * the data from the safe buffer back to the unsafe buffer and free up

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

+10 −1
Original line number Diff line number Diff line
@@ -227,13 +227,22 @@ extern dma_addr_t dma_map_single(struct device *,void *, size_t, enum dma_data_d 
 * can regain ownership by calling dma_unmap_page() or

 * dma_sync_single_for_cpu().

 */

#ifndef CONFIG_DMABOUNCE

static inline dma_addr_t

dma_map_page(struct device *dev, struct page *page,

	     unsigned long offset, size_t size,

	     enum dma_data_direction dir)

{

	return dma_map_single(dev, page_address(page) + offset, size, dir);

	if (!arch_is_coherent())

		dma_cache_maint(page_address(page) + offset, size, dir);



	return page_to_dma(dev, page) + offset;

}

#else

extern dma_addr_t dma_map_page(struct device *dev, struct page *page,

			unsigned long offset, size_t size,

			enum dma_data_direction dir);

#endif



/**

 * dma_unmap_single - unmap a single buffer previously mapped