Messages in this thread | | | From | Rob Clark <> | Date | Thu, 29 Nov 2018 13:48:15 -0500 | Subject | Re: [PATCH v3 1/1] drm: msm: Replace dma_map_sg with dma_sync_sg* |
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On Thu, Nov 29, 2018 at 10:54 AM Christoph Hellwig <hch@lst.de> wrote: > > On Thu, Nov 29, 2018 at 09:42:50AM -0500, Rob Clark wrote: > > Maybe the thing we need to do is just implement a blacklist of > > compatible strings for devices which should skip the automatic > > iommu/dma hookup. Maybe a bit ugly, but it would also solve a problem > > preventing us from enabling per-process pagetables for a5xx (where we > > need to control the domain/context-bank that is allocated by the dma > > api). > > You can detach from the dma map attachment using arm_iommu_detach_device, > which a few drm drivers do, but I don't think this is the problem.
I think even with detach, we wouldn't end up with the context-bank that the gpu firmware was hard-coded to expect, and so it would overwrite the incorrect page table address register. (I could be mis-remembering that, Jordan spent more time looking at that. But it was something along those lines.)
BR, -R
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