diff options
Diffstat (limited to 'Documentation/DMA-API.txt')
| -rw-r--r-- | Documentation/DMA-API.txt | 55 |
1 files changed, 17 insertions, 38 deletions
diff --git a/Documentation/DMA-API.txt b/Documentation/DMA-API.txt index 45b29326d719..ac66ae2509a9 100644 --- a/Documentation/DMA-API.txt +++ b/Documentation/DMA-API.txt @@ -515,14 +515,15 @@ API at all. :: void * - dma_alloc_noncoherent(struct device *dev, size_t size, - dma_addr_t *dma_handle, gfp_t flag) + dma_alloc_attrs(struct device *dev, size_t size, dma_addr_t *dma_handle, + gfp_t flag, unsigned long attrs) -Identical to dma_alloc_coherent() except that the platform will -choose to return either consistent or non-consistent memory as it sees -fit. By using this API, you are guaranteeing to the platform that you -have all the correct and necessary sync points for this memory in the -driver should it choose to return non-consistent memory. +Identical to dma_alloc_coherent() except that when the +DMA_ATTR_NON_CONSISTENT flags is passed in the attrs argument, the +platform will choose to return either consistent or non-consistent memory +as it sees fit. By using this API, you are guaranteeing to the platform +that you have all the correct and necessary sync points for this memory +in the driver should it choose to return non-consistent memory. Note: where the platform can return consistent memory, it will guarantee that the sync points become nops. @@ -535,12 +536,13 @@ that simply cannot make consistent memory. :: void - dma_free_noncoherent(struct device *dev, size_t size, void *cpu_addr, - dma_addr_t dma_handle) + dma_free_attrs(struct device *dev, size_t size, void *cpu_addr, + dma_addr_t dma_handle, unsigned long attrs) -Free memory allocated by the nonconsistent API. All parameters must -be identical to those passed in (and returned by -dma_alloc_noncoherent()). +Free memory allocated by the dma_alloc_attrs(). All parameters common +parameters must identical to those otherwise passed to dma_fre_coherent, +and the attrs argument must be identical to the attrs passed to +dma_alloc_attrs(). :: @@ -564,8 +566,8 @@ memory or doing partial flushes. dma_cache_sync(struct device *dev, void *vaddr, size_t size, enum dma_data_direction direction) -Do a partial sync of memory that was allocated by -dma_alloc_noncoherent(), starting at virtual address vaddr and +Do a partial sync of memory that was allocated by dma_alloc_attrs() with +the DMA_ATTR_NON_CONSISTENT flag starting at virtual address vaddr and continuing on for size. Again, you *must* observe the cache line boundaries when doing this. @@ -590,34 +592,11 @@ size is the size of the area (must be multiples of PAGE_SIZE). flags can be ORed together and are: -- DMA_MEMORY_MAP - request that the memory returned from - dma_alloc_coherent() be directly writable. - -- DMA_MEMORY_IO - request that the memory returned from - dma_alloc_coherent() be addressable using read()/write()/memcpy_toio() etc. - -One or both of these flags must be present. - -- DMA_MEMORY_INCLUDES_CHILDREN - make the declared memory be allocated by - dma_alloc_coherent of any child devices of this one (for memory residing - on a bridge). - - DMA_MEMORY_EXCLUSIVE - only allocate memory from the declared regions. Do not allow dma_alloc_coherent() to fall back to system memory when it's out of memory in the declared region. -The return value will be either DMA_MEMORY_MAP or DMA_MEMORY_IO and -must correspond to a passed in flag (i.e. no returning DMA_MEMORY_IO -if only DMA_MEMORY_MAP were passed in) for success or zero for -failure. - -Note, for DMA_MEMORY_IO returns, all subsequent memory returned by -dma_alloc_coherent() may no longer be accessed directly, but instead -must be accessed using the correct bus functions. If your driver -isn't prepared to handle this contingency, it should not specify -DMA_MEMORY_IO in the input flags. - -As a simplification for the platforms, only **one** such region of +As a simplification for the platforms, only *one* such region of memory may be declared per device. For reasons of efficiency, most platforms choose to track the declared |
