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iommu/dma: Remove bogus dma_supported() implementation 

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>
This commit is contained in:
Robin Murphy 2017-02-01 17:53:04 +00:00 committed by Joerg Roedel
parent 122fac030e
commit a1831bb940
3 changed files with 0 additions and 12 deletions
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1
arch/arm64/mm/dma-mapping.c
View File

@ -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,
};

10
drivers/iommu/dma-iommu.c
View File

@ -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;

1
include/linux/dma-iommu.h
View File

@ -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... */