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iommu/dma: Remove bogus dma_supported() implementation

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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>
Git-commit: a1831bb9403720db6d4c033fe2d6bd0116dd28fe
Git-repo:git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git

CRs-Fixed: 2040683
Change-Id: I67431608ce196bf5ca981fb9aea2afce826094f0
Signed-off-by: Atul Raut <araut@codeaurora.org>
This commit is contained in:
Robin Murphy 2017-04-30 09:56:16 -07:00 • committed by Gerrit - the friendly Code Review server
parent d992f38d6d
commit eb7038b13a
3 changed files with 0 additions and 12 deletions
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1
arch/arm64/mm/dma-mapping.c
View file

@ -929,7 +929,6 @@ static struct dma_map_ops iommu_dma_ops = {
.sync_single_for_device = __iommu_sync_single_for_device,
.sync_sg_for_cpu = __iommu_sync_sg_for_cpu,
.sync_sg_for_device = __iommu_sync_sg_for_device,
.dma_supported = iommu_dma_supported,
.mapping_error = iommu_dma_mapping_error,
};

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

@ -514,16 +514,6 @@ void iommu_dma_unmap_sg(struct device *dev, struct scatterlist *sg, int nents,
__iommu_dma_unmap(iommu_get_domain_for_dev(dev), sg_dma_address(sg));
}
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

@ -59,7 +59,6 @@ void iommu_dma_unmap_page(struct device *dev, dma_addr_t handle, size_t size,
enum dma_data_direction dir, struct dma_attrs *attrs);
void iommu_dma_unmap_sg(struct device *dev, struct scatterlist *sg, int nents,
enum dma_data_direction dir, struct dma_attrs *attrs);
int iommu_dma_supported(struct device *dev, u64 mask);
int iommu_dma_mapping_error(struct device *dev, dma_addr_t dma_addr);
#else