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common: DMA-mapping: add DMA_ATTR_FORCE_CONTIGUOUS attribute 

This patch adds DMA_ATTR_FORCE_CONTIGUOUS attribute to the DMA-mapping
subsystem.

By default DMA-mapping subsystem is allowed to assemble the buffer
allocated by dma_alloc_attrs() function from individual pages if it can
be mapped as contiguous chunk into device dma address space. By
specifing this attribute the allocated buffer is forced to be contiguous
also in physical memory.

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
This commit is contained in:
Marek Szyprowski 2012-10-15 16:03:51 +02:00 committed by Inki Dae
parent e7783ba3bf
commit 4b9347dcbe
2 changed files with 10 additions and 0 deletions
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9
Documentation/DMA-attributes.txt
View File

@ -91,3 +91,12 @@ transferred to 'device' domain. This attribute can be also used for
dma_unmap_{single,page,sg} functions family to force buffer to stay in
device domain after releasing a mapping for it. Use this attribute with
care!
DMA_ATTR_FORCE_CONTIGUOUS
-------------------------
By default DMA-mapping subsystem is allowed to assemble the buffer
allocated by dma_alloc_attrs() function from individual pages if it can
be mapped as contiguous chunk into device dma address space. By
specifing this attribute the allocated buffer is forced to be contiguous
also in physical memory.

1
include/linux/dma-attrs.h
View File

@ -17,6 +17,7 @@ enum dma_attr {
DMA_ATTR_NON_CONSISTENT,
DMA_ATTR_NO_KERNEL_MAPPING,
DMA_ATTR_SKIP_CPU_SYNC,
DMA_ATTR_FORCE_CONTIGUOUS,
DMA_ATTR_MAX,
};