diff options
-rw-r--r-- | Documentation/DMA-API-HOWTO.txt | 17 |
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". | |||
703 | 703 | ||
704 | 1) Struct scatterlist requirements. | 704 | 1) Struct scatterlist requirements. |
705 | 705 | ||
706 | Struct scatterlist must contain, at a minimum, the following | 706 | Don't invent the architecture specific struct scatterlist; just use |
707 | members: | 707 | <asm-generic/scatterlist.h>. You need to enable |
708 | 708 | CONFIG_NEED_SG_DMA_LENGTH if the architecture supports IOMMUs | |
709 | struct page *page; | 709 | (including software IOMMU). |
710 | unsigned int offset; | ||
711 | unsigned int length; | ||
712 | |||
713 | The base address is specified by a "page+offset" pair. | ||
714 | |||
715 | Previous versions of struct scatterlist contained a "void *address" | ||
716 | field that was sometimes used instead of page+offset. As of Linux | ||
717 | 2.5., page+offset is always used, and the "address" field has been | ||
718 | deleted. | ||
719 | 710 | ||
720 | 2) More to come... | 711 | 2) More to come... |
721 | 712 | ||