Merge branch 'for-v4.1-rc1' of git://git.linaro.org/people/mszyprowski/linux-dma-mapping

Pull DMA-mapping updates from Marek Szyprowski:
 "This contains two patches, which clarify abiguity in the dma-mapping
  api"

* 'for-v4.1-rc1' of git://git.linaro.org/people/mszyprowski/linux-dma-mapping:
  include/dma-mapping: Clarify output of dma_map_sg
  asm/dma-mapping-common: Clarify output of dma_map_sg_attrs

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

@@ -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;

include/linux/dma-mapping.h

@@ -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);