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-rw-r--r--Documentation/DMA-API-HOWTO.txt17
1 files changed, 4 insertions, 13 deletions
diff --git a/Documentation/DMA-API-HOWTO.txt b/Documentation/DMA-API-HOWTO.txt
index a38ddadd208e..c3ab456422f3 100644
--- a/Documentation/DMA-API-HOWTO.txt
+++ b/Documentation/DMA-API-HOWTO.txt
@@ -703,19 +703,10 @@ to "Closing".
1) Struct scatterlist requirements.
- Struct scatterlist must contain, at a minimum, the following
- members:
-
- struct page *page;
- unsigned int offset;
- unsigned int length;
-
- The base address is specified by a "page+offset" pair.
-
- Previous versions of struct scatterlist contained a "void *address"
- field that was sometimes used instead of page+offset. As of Linux
- 2.5., page+offset is always used, and the "address" field has been
- deleted.
+ Don't invent the architecture specific struct scatterlist; just use
+ <asm-generic/scatterlist.h>. You need to enable
+ CONFIG_NEED_SG_DMA_LENGTH if the architecture supports IOMMUs
+ (including software IOMMU).
2) More to come...