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Commit 8582e267 authored by Ricardo Ribalda Delgado's avatar Ricardo Ribalda Delgado Committed by Marek Szyprowski
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asm/dma-mapping-common: Clarify output of dma_map_sg_attrs 



Although dma_map_sg_attrs returns 0 on error and it cannot return a
value < 0, the function returns a signed integer.

Most of the time, this function is used with a scatterlist structure.
This structure uses an unsigned integer for the number of memory.

A dma developer that has not read in detail DMA-API.txt, can wrongly
return a value < 0 on error.

The comment will help the driver developer, and the WARN_ON the dma
developer.

Signed-off-by: default avatarRicardo Ribalda Delgado <ricardo.ribalda@gmail.com>
Signed-off-by: default avatarMarek Szyprowski <m.szyprowski@samsung.com>
parent 9eccca08

include/asm-generic/dma-mapping-common.h

+5 −0
Original line number Diff line number Diff line
@@ -39,6 +39,10 @@ static inline void dma_unmap_single_attrs(struct device *dev, dma_addr_t addr, 
	debug_dma_unmap_page(dev, addr, size, dir, true);

}



/*

 * dma_maps_sg_attrs returns 0 on error and > 0 on success.

 * It should never return a value < 0.

 */

static inline int dma_map_sg_attrs(struct device *dev, struct scatterlist *sg,

				   int nents, enum dma_data_direction dir,

				   struct dma_attrs *attrs)
@@ -51,6 +55,7 @@ static inline int dma_map_sg_attrs(struct device *dev, struct scatterlist *sg, 
		kmemcheck_mark_initialized(sg_virt(s), s->length);

	BUG_ON(!valid_dma_direction(dir));

	ents = ops->map_sg(dev, sg, nents, dir, attrs);

	BUG_ON(ents < 0);

	debug_dma_map_sg(dev, sg, nents, ents, dir);



	return ents;