This is part of an ongoing evolution for enabling split pagetable support for arm-smmu. Previous versions can be found [1]. In the discussion for v2 Robin pointed out that this is a very Adreno specific use case and that is exactly true. Not only do we want to configure and use a pagetable in the TTBR1 space, we also want to configure the TTBR0 region but not allocate a pagetable for it or touch it until the GPU hardware does so. As much as I want it to be a generic concept it really isn't. This revision leans into that idea. Most of the same io-pgtable code is there but now it is wrapped as an Adreno GPU specific format that is selected by the compatible string in the arm-smmu device. Additionally, per Robin's suggestion we are skipping creating a TTBR0 pagetable to save on wasted memory. This isn't as clean as I would like it to be but I think that this is a better direction than trying to pretend that the generic format would work. I'm tempting fate by posting this and then taking some time off, but I wanted to try to kick off a conversation or at least get some flames so I can try to refine this again next week. Please take a look and give some advice on the direction. [1] https://patchwork.freedesktop.org/series/63403/ Jordan Jordan Crouse (2): iommu/io-pgtable-arm: Add support for ARM_ADRENO_GPU_LPAE io-pgtable format iommu/arm-smmu: Add support for Adreno GPU pagetable formats drivers/iommu/arm-smmu.c | 8 +- drivers/iommu/io-pgtable-arm.c | 214 ++++++++++++++++++++++++++++++++++++++--- drivers/iommu/io-pgtable.c | 1 + include/linux/io-pgtable.h | 2 + 4 files changed, 209 insertions(+), 16 deletions(-) -- 2.7.4
