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Commit 827325a0 authored Nov 03, 2016 by Patrick Daly

dma-mapping: Introduce DMA_ATTR_IOMMU_USE_UPSTREAM_HINT



Add documentation for this new attribute. It will be used on the
skunk target for allowing smmu clients to set the bus attributes
required to use system cache.

Change-Id: Id0b0dc261e46082ac48accdeb949947dce375d28
Signed-off-by: Patrick Daly <pdaly@codeaurora.org>

parent b13a28ff

Documentation/DMA-attributes.txt

+7 −0

Original line number	Diff line number	Diff line
		@@ -169,3 +169,10 @@ DMA_ATTR_EXEC_MAPPING
		By default, the DMA mappings are non-executable. Some use cases might require
		an executable mapping. This attribute can be used to indicate to the DMA
		subsystem to create an executable mappings for the buffer.

		DMA_ATTR_IOMMU_USE_UPSTREAM_HINT
		--------------------------------

		DMA_ATTR_IOMMU_USE_UPSTREAM_HINT: Normally an smmu will override any bus
		attributes (i.e cacheablilty) provided by the client device. Some hardware
		may be designed to use the original attributes instead.

include/linux/dma-mapping.h

+6 −0

Original line number	Diff line number	Diff line
		@@ -81,6 +81,12 @@
		* DMA_ATTR_EXEC_MAPPING: The mapping has executable permissions.
		*/
		#define DMA_ATTR_EXEC_MAPPING (1UL << 12)
		/*
		* DMA_ATTR_IOMMU_USE_UPSTREAM_HINT: Normally an smmu will override any bus
		* attributes (i.e cacheablilty) provided by the client device. Some hardware
		* may be designed to use the original attributes instead.
		*/
		#define DMA_ATTR_IOMMU_USE_UPSTREAM_HINT (1UL << 13)

		/*
		* A dma_addr_t can hold any valid DMA or bus address for the platform.