diff options
Diffstat (limited to 'Documentation/DMA-attributes.txt')
-rw-r--r-- | Documentation/DMA-attributes.txt | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/Documentation/DMA-attributes.txt b/Documentation/DMA-attributes.txt index e59480db9ee0..cc2450d80310 100644 --- a/Documentation/DMA-attributes.txt +++ b/Documentation/DMA-attributes.txt | |||
@@ -13,7 +13,7 @@ all pending DMA writes to complete, and thus provides a mechanism to | |||
13 | strictly order DMA from a device across all intervening busses and | 13 | strictly order DMA from a device across all intervening busses and |
14 | bridges. This barrier is not specific to a particular type of | 14 | bridges. This barrier is not specific to a particular type of |
15 | interconnect, it applies to the system as a whole, and so its | 15 | interconnect, it applies to the system as a whole, and so its |
16 | implementation must account for the idiosyncracies of the system all | 16 | implementation must account for the idiosyncrasies of the system all |
17 | the way from the DMA device to memory. | 17 | the way from the DMA device to memory. |
18 | 18 | ||
19 | As an example of a situation where DMA_ATTR_WRITE_BARRIER would be | 19 | As an example of a situation where DMA_ATTR_WRITE_BARRIER would be |
@@ -60,7 +60,7 @@ such mapping is non-trivial task and consumes very limited resources | |||
60 | Buffers allocated with this attribute can be only passed to user space | 60 | Buffers allocated with this attribute can be only passed to user space |
61 | by calling dma_mmap_attrs(). By using this API, you are guaranteeing | 61 | by calling dma_mmap_attrs(). By using this API, you are guaranteeing |
62 | that you won't dereference the pointer returned by dma_alloc_attr(). You | 62 | that you won't dereference the pointer returned by dma_alloc_attr(). You |
63 | can threat it as a cookie that must be passed to dma_mmap_attrs() and | 63 | can treat it as a cookie that must be passed to dma_mmap_attrs() and |
64 | dma_free_attrs(). Make sure that both of these also get this attribute | 64 | dma_free_attrs(). Make sure that both of these also get this attribute |
65 | set on each call. | 65 | set on each call. |
66 | 66 | ||
@@ -82,7 +82,7 @@ to 'device' domain, what synchronizes CPU caches for the given region | |||
82 | (usually it means that the cache has been flushed or invalidated | 82 | (usually it means that the cache has been flushed or invalidated |
83 | depending on the dma direction). However, next calls to | 83 | depending on the dma direction). However, next calls to |
84 | dma_map_{single,page,sg}() for other devices will perform exactly the | 84 | dma_map_{single,page,sg}() for other devices will perform exactly the |
85 | same sychronization operation on the CPU cache. CPU cache sychronization | 85 | same synchronization operation on the CPU cache. CPU cache synchronization |
86 | might be a time consuming operation, especially if the buffers are | 86 | might be a time consuming operation, especially if the buffers are |
87 | large, so it is highly recommended to avoid it if possible. | 87 | large, so it is highly recommended to avoid it if possible. |
88 | DMA_ATTR_SKIP_CPU_SYNC allows platform code to skip synchronization of | 88 | DMA_ATTR_SKIP_CPU_SYNC allows platform code to skip synchronization of |