[PATCHv2 13/14] common: DMA-mapping: add WRITE_COMBINE attribute
From: Marek Szyprowski <m.szyprowski@samsung.com>
Date: 2012-03-27 13:43:30
Also in:
linux-alpha, linux-arm-kernel, linux-mips, linux-mm, linuxppc-dev
Subsystem:
documentation, the rest · Maintainers:
Jonathan Corbet, Linus Torvalds
DMA_ATTR_WRITE_COMBINE specifies that writes to the mapping may be buffered to improve performance. It will be used by the replacement for ARM/ARV32 specific dma_alloc_writecombine() function. Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com> Acked-by: Kyungmin Park <kyungmin.park@samsung.com> Reviewed-by: Arnd Bergmann <arnd@arndb.de> --- Documentation/DMA-attributes.txt | 10 ++++++++++ include/linux/dma-attrs.h | 1 + 2 files changed, 11 insertions(+), 0 deletions(-)
diff --git a/Documentation/DMA-attributes.txt b/Documentation/DMA-attributes.txt
index b768cc0..811a5d4 100644
--- a/Documentation/DMA-attributes.txt
+++ b/Documentation/DMA-attributes.txt@@ -31,3 +31,13 @@ may be weakly ordered, that is that reads and writes may pass each other. Since it is optional for platforms to implement DMA_ATTR_WEAK_ORDERING, those that do not will simply ignore the attribute and exhibit default behavior. + +DMA_ATTR_WRITE_COMBINE +---------------------- + +DMA_ATTR_WRITE_COMBINE specifies that writes to the mapping may be +buffered to improve performance. + +Since it is optional for platforms to implement DMA_ATTR_WRITE_COMBINE, +those that do not will simply ignore the attribute and exhibit default +behavior.
diff --git a/include/linux/dma-attrs.h b/include/linux/dma-attrs.h
index 71ad34e..ada61e1 100644
--- a/include/linux/dma-attrs.h
+++ b/include/linux/dma-attrs.h@@ -13,6 +13,7 @@ enum dma_attr { DMA_ATTR_WRITE_BARRIER, DMA_ATTR_WEAK_ORDERING, + DMA_ATTR_WRITE_COMBINE, DMA_ATTR_MAX, };
--
1.7.1.569.g6f426
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