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Commit 7e89aa76 authored by Liam Mark's avatar Liam Mark Committed by Gerrit - the friendly Code Review server
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common: DMA-mapping: add per-buffer coherent mappings attributes 



The DMA_ATTR_FORCE_COHERENT DMA attribute can be used to force a buffer
to be mapped as IO coherent.

The DMA_ATTR_FORCE_NON_COHERENT DMA attribute can be used to force a
buffer to not be mapped as IO coherent.

Change-Id: Id80d77a5ccd797eec36b45b320423fb46c9f5861
Signed-off-by: default avatarLiam Mark <lmark@codeaurora.org>
parent cca05311

Documentation/DMA-attributes.txt

+19 −0
Original line number Diff line number Diff line
@@ -126,3 +126,22 @@ 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_FORCE_COHERENT

-----------------------



When passed to a DMA map call the DMA_ATTR_FORCE_COHERENT DMA

attribute can be used to force a buffer to be mapped as IO coherent.

This DMA attribute is only currently supported for arm64 stage 1 IOMMU

mappings.



DMA_ATTR_FORCE_NON_COHERENT

---------------------------

When passed to a DMA map call the DMA_ATTR_FORCE_NON_COHERENT DMA

attribute can be used to force a buffer to not be mapped as IO

coherent.

The DMA_ATTR_FORCE_NON_COHERENT DMA attribute overrides the buffer IO

coherency configuration set by making the device IO coherent.



This DMA attribute is only currently supported for arm64 stage 1 IOMMU

mappings.

include/linux/dma-attrs.h

+2 −0
Original line number Diff line number Diff line
@@ -22,6 +22,8 @@ enum dma_attr { 
	DMA_ATTR_SKIP_ZEROING,

	DMA_ATTR_NO_DELAYED_UNMAP,

	DMA_ATTR_EXEC_MAPPING,

	DMA_ATTR_FORCE_COHERENT,

	DMA_ATTR_FORCE_NON_COHERENT,

	DMA_ATTR_MAX,

};