Hi Will, On Wednesday 21 January 2015 14:48:35 Will Deacon wrote: > On Tue, Jan 20, 2015 at 04:56:03PM +0000, Laurent Pinchart wrote: > > On Monday 19 January 2015 16:06:20 Will Deacon wrote: > > > On Fri, Nov 14, 2014 at 08:01:56PM +0000, Arnd Bergmann wrote: > > > > On Friday 14 November 2014 19:27:54 Will Deacon wrote: > > > > > > At the moment, iommu_ops is a structure that can get used for any > > > > > > number of iommus of the same type, but by putting per-device > > > > > > private data into the same structure you have to duplicate it per > > > > > > instance. > > > > > > > > > > I'm not sure I agree -- the pgsize_bitmap, for example, could vary > > > > > between different implementations of the same IOMMU. I think we > > > > > already have this in Juno (some SMMUs can only do 64k pages, whilst > > > > > others can do 4k and 64k). > > > > > > > > Ah, I hadn't noticed that, it should be in the 'struct iommu' then of > > > > course, not in iommu_ops. > > > > > > Now that of_iommu_get_ops has its own list of iommu_ops, we can actually > > > just move pgsize_bitmap into the iommu_domain, which I think makes a lot > > > more sense anyway. > > > > The code looks good to me, but what does it have to do with > > of_iommu_get_ops() having its own list of iommu_ops ? > > So, the initial patches for of_iommu_configure/of_xlate made use of a void > *priv field in struct iommu_ops (which actually made it to mainline but > isn't used). This was replaced by the list maintained by of_iommu_get_ops, > but the discussion highlighted that iommu_ops is not per-IOMMU instance and > therefore shouldn't contain the pgsize_bitmap, which can (and does) vary > between different IOMMU instances in a running system. > > This patch is an effort to move the pgsize_bitmap field out of iommu_ops > (leaving that structure to contain only function pointers) and into > iommu_domain, where I think it makes more sense.
OK, that's what I had understood. Thanks for the clarification. I was just puzzled by what I thought you meant was a dependency on of_iommu_get_ops(). > > > diff below seems to do the trick. The next step would be postponing the > > > pgsize_bitmap initialisation until device attach for the ARM SMMU, since > > > it's at that point that we know the active page table format (and > > > therefore the supported page sizes). -- Regards, Laurent Pinchart _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
