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Commit c03b5c2d authored by Linux Build Service Account's avatar Linux Build Service Account Committed by Gerrit - the friendly Code Review server
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Merge "arm64: dma-mapping: optimize unmap coherency check"

parents 75774331 37a29f16

Documentation/DMA-attributes.txt

+9 −0
Original line number Diff line number Diff line
@@ -132,6 +132,11 @@ 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.



When the DMA_ATTR_FORCE_COHERENT attribute is set during a map call ensure

that it is also set during for the matching unmap call to ensure that the

correct cache maintenance is carried out.



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

mappings.
@@ -143,5 +148,9 @@ coherent. 
The DMA_ATTR_FORCE_NON_COHERENT DMA attribute overrides the buffer IO

coherency configuration set by making the device IO coherent.



When the DMA_ATTR_FORCE_NON_COHERENT attribute is set during a map call

ensure that it is also set during for the matching unmap call to ensure

that the correct cache maintenance is carried out.



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

mappings.

arch/arm64/mm/dma-mapping.c

+1 −3
Original line number Diff line number Diff line
@@ -1821,10 +1821,8 @@ static void arm_iommu_unmap_page(struct device *dev, dma_addr_t handle, 
						mapping->domain, iova));

	int offset = handle & ~PAGE_MASK;

	int len = PAGE_ALIGN(size + offset);

	bool iova_coherent = iommu_is_iova_coherent(mapping->domain,

							handle);



	if (!(iova_coherent ||

	if (!(is_dma_coherent(dev, attrs) ||

	      dma_get_attr(DMA_ATTR_SKIP_CPU_SYNC, attrs)))

		__dma_page_dev_to_cpu(page, offset, size, dir);