From b02de871617be353c941edce5f7c22bb18499b4e Mon Sep 17 00:00:00 2001 From: FUJITA Tomonori Date: Wed, 26 May 2010 14:44:21 -0700 Subject: [PATCH] Documentation: update scatterlist struct description in DMA-API-HOWTO Now we have . 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 --- Documentation/DMA-API-HOWTO.txt | 17 ++++------------- 1 file 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 + . You need to enable + CONFIG_NEED_SG_DMA_LENGTH if the architecture supports IOMMUs + (including software IOMMU). 2) More to come... -- 2.20.1