On 10/11/16 12:24, Joerg Roedel wrote: > On Wed, Oct 26, 2016 at 06:43:56PM +0100, Robin Murphy wrote: >> With the new dma_{map,unmap}_resource() functions added to the DMA API >> for the benefit of cases like slave DMA, add suitable implementations to >> the arsenal of our generic layer. Since cache maintenance should not be >> a concern, these can both be standalone callback implementations without >> the need for arch code wrappers. >> >> CC: Joerg Roedel <j...@8bytes.org> >> Signed-off-by: Robin Murphy <robin.mur...@arm.com> >> --- >> >> v2: Use iommu_dma_unmap_page for symmetry, instead of being sneaky. >> >> drivers/iommu/dma-iommu.c | 13 +++++++++++++ >> include/linux/dma-iommu.h | 4 ++++ >> 2 files changed, 17 insertions(+) >> >> diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c >> index c5ab8667e6f2..a2fd90a6a782 100644 >> --- a/drivers/iommu/dma-iommu.c >> +++ b/drivers/iommu/dma-iommu.c >> @@ -624,6 +624,19 @@ 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)); >> } >> >> +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) >> +{ >> + return iommu_dma_map_page(dev, phys_to_page(phys), offset_in_page(phys), >> + size, dma_direction_to_prot(dir, false) | IOMMU_MMIO); >> +} > > Isn't the whole point of map_resource that we can map regions which have > no 'struct page' associated? The use phys_to_page() will certainly not > do the right thing here.
Perhaps it's a bit cheeky, but the struct page pointer is never dereferenced - the only thing iommu_dma_map_page() does with it is immediately convert it back again. Is there ever a case where page_to_phys(phys_to_page(phys)) != phys ? Robin. _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu