iommu/dma: Remove bogus dma_supported() implementation (a1831bb9) · Commits · 戴 / test

Back when this was first written, dma_supported() was somewhat of a murky mess, with subtly different interpretations being relied upon in various places. The "does device X support DMA to address range Y?" uses assuming Y to be physical addresses, which motivated the current iommu_dma_supported() implementation and are alluded to in the comment therein, have since been cleaned up, leaving only the far less ambiguous "can device X drive address bits Y" usage internal to DMA API mask setting. As such, there is no reason to keep a slightly misleading callback which does nothing but duplicate the current default behaviour; we already constrain IOVA allocations to the iommu_domain aperture where necessary, so let's leave DMA mask business to architecture-specific code where it belongs. Signed-off-by:

Robin Murphy <robin.murphy@arm.com> Signed-off-by:

Joerg Roedel <jroedel@suse.de>

arch/arm64/mm/dma-mapping.c

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Original line number	Diff line number	Diff line
		@@ -799,7 +799,6 @@ static struct dma_map_ops iommu_dma_ops = {
		.sync_sg_for_device = __iommu_sync_sg_for_device,
		.map_resource = iommu_dma_map_resource,
		.unmap_resource = iommu_dma_unmap_resource,
		.dma_supported = iommu_dma_supported,
		.mapping_error = iommu_dma_mapping_error,
		};

drivers/iommu/dma-iommu.c

+0 −10

Original line number	Diff line number	Diff line
		@@ -734,16 +734,6 @@ void iommu_dma_unmap_resource(struct device *dev, dma_addr_t handle,
		__iommu_dma_unmap(iommu_get_domain_for_dev(dev), handle);
		}

		int iommu_dma_supported(struct device *dev, u64 mask)
		{
		/*
		* 'Special' IOMMUs which don't have the same addressing capability
		* as the CPU will have to wait until we have some way to query that
		* before they'll be able to use this framework.
		*/
		return 1;
		}

		int iommu_dma_mapping_error(struct device *dev, dma_addr_t dma_addr)
		{
		return dma_addr == DMA_ERROR_CODE;

include/linux/dma-iommu.h

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Original line number	Diff line number	Diff line
		@@ -67,7 +67,6 @@ dma_addr_t iommu_dma_map_resource(struct device *dev, phys_addr_t phys,
		size_t size, enum dma_data_direction dir, unsigned long attrs);
		void iommu_dma_unmap_resource(struct device *dev, dma_addr_t handle,
		size_t size, enum dma_data_direction dir, unsigned long attrs);
		int iommu_dma_supported(struct device *dev, u64 mask);
		int iommu_dma_mapping_error(struct device *dev, dma_addr_t dma_addr);

		/* The DMA API isn't _quite_ the whole story, though... */

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