diff options
Diffstat (limited to 'Documentation/DMA-API.txt')
| -rw-r--r-- | Documentation/DMA-API.txt | 33 |
1 files changed, 14 insertions, 19 deletions
diff --git a/Documentation/DMA-API.txt b/Documentation/DMA-API.txt index 45ef3f279c3b..1d26eeb6b5f6 100644 --- a/Documentation/DMA-API.txt +++ b/Documentation/DMA-API.txt @@ -369,35 +369,32 @@ See also dma_map_single(). dma_addr_t dma_map_single_attrs(struct device *dev, void *cpu_addr, size_t size, enum dma_data_direction dir, - struct dma_attrs *attrs) + unsigned long attrs) void dma_unmap_single_attrs(struct device *dev, dma_addr_t dma_addr, size_t size, enum dma_data_direction dir, - struct dma_attrs *attrs) + unsigned long attrs) int dma_map_sg_attrs(struct device *dev, struct scatterlist *sgl, int nents, enum dma_data_direction dir, - struct dma_attrs *attrs) + unsigned long attrs) void dma_unmap_sg_attrs(struct device *dev, struct scatterlist *sgl, int nents, enum dma_data_direction dir, - struct dma_attrs *attrs) + unsigned long attrs) The four functions above are just like the counterpart functions without the _attrs suffixes, except that they pass an optional -struct dma_attrs*. - -struct dma_attrs encapsulates a set of "DMA attributes". For the -definition of struct dma_attrs see linux/dma-attrs.h. +dma_attrs. The interpretation of DMA attributes is architecture-specific, and each attribute should be documented in Documentation/DMA-attributes.txt. -If struct dma_attrs* is NULL, the semantics of each of these -functions is identical to those of the corresponding function +If dma_attrs are 0, the semantics of each of these functions +is identical to those of the corresponding function without the _attrs suffix. As a result dma_map_single_attrs() can generally replace dma_map_single(), etc. @@ -405,15 +402,15 @@ As an example of the use of the *_attrs functions, here's how you could pass an attribute DMA_ATTR_FOO when mapping memory for DMA: -#include <linux/dma-attrs.h> -/* DMA_ATTR_FOO should be defined in linux/dma-attrs.h and +#include <linux/dma-mapping.h> +/* DMA_ATTR_FOO should be defined in linux/dma-mapping.h and * documented in Documentation/DMA-attributes.txt */ ... - DEFINE_DMA_ATTRS(attrs); - dma_set_attr(DMA_ATTR_FOO, &attrs); + unsigned long attr; + attr |= DMA_ATTR_FOO; .... - n = dma_map_sg_attrs(dev, sg, nents, DMA_TO_DEVICE, &attr); + n = dma_map_sg_attrs(dev, sg, nents, DMA_TO_DEVICE, attr); .... Architectures that care about DMA_ATTR_FOO would check for its @@ -422,12 +419,10 @@ routines, e.g.: void whizco_dma_map_sg_attrs(struct device *dev, dma_addr_t dma_addr, size_t size, enum dma_data_direction dir, - struct dma_attrs *attrs) + unsigned long attrs) { .... - int foo = dma_get_attr(DMA_ATTR_FOO, attrs); - .... - if (foo) + if (attrs & DMA_ATTR_FOO) /* twizzle the frobnozzle */ .... |