path: root/Documentation/DMA-API-HOWTO.txt
diff options
authorFUJITA Tomonori <>2010-05-26 14:44:21 -0700
committerLinus Torvalds <>2010-05-27 09:12:53 -0700
commitb02de871617be353c941edce5f7c22bb18499b4e (patch)
tree5d4d9cc22118ae3f4ecd134d1ce31ae3e95d33e0 /Documentation/DMA-API-HOWTO.txt
parent7cdcc8e4762f0e4a94cead6a3b57b5eaa01bd5da (diff)
Documentation: update scatterlist struct description in DMA-API-HOWTO
Now we have <asm-generic/scatterlist.h>. Architectures should use it instead of inventing the own scatterlist struct. Let's update the description. Signed-off-by: FUJITA Tomonori <> Signed-off-by: Andrew Morton <> Signed-off-by: Linus Torvalds <>
Diffstat (limited to 'Documentation/DMA-API-HOWTO.txt')
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...