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include/dma-mapping: Clarify output of dma_map_sg 

Although dma_map_sg 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.

Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
This commit is contained in:
Ricardo Ribalda Delgado 2015-02-11 13:53:15 +01:00 committed by Marek Szyprowski
parent 8582e267e9
commit 04abab6982
1 changed files with 4 additions and 0 deletions
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4
include/linux/dma-mapping.h
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@ -34,6 +34,10 @@ struct dma_map_ops {
void (*unmap_page)(struct device *dev, dma_addr_t dma_handle,
size_t size, enum dma_data_direction dir,
struct dma_attrs *attrs);
/*
* map_sg returns 0 on error and a value > 0 on success.
* It should never return a value < 0.
*/
int (*map_sg)(struct device *dev, struct scatterlist *sg,
int nents, enum dma_data_direction dir,
struct dma_attrs *attrs);