search for: explicit_iommu

...gure() could still set that up, perhaps based on some DT property, though I can already hear the NAK from DT maintainers because this is, after all, policy, not hardware description. The last solution that I can think of that might allow us to do this is to add a flag to struct device_driver (bool explicit_iommu?) that will be used by the DMA/IOMMU setup code to decide whether or not to attach to the IOMMU automatically. Though, again, I'm not sure that would actually solve your bank problem. That's really something I don't see any other solution than to fix it in the ARM SMMU driver. Perhaps...

On Wed, Apr 25, 2018 at 12:10:47PM +0200, Thierry Reding wrote: > From: Thierry Reding <treding at nvidia.com> > > Depending on the kernel configuration, early ARM architecture setup code > may have attached the GPU to a DMA/IOMMU mapping that transparently uses > the IOMMU to back the DMA API. Tegra requires special handling for IOMMU > backed buffers (a special bit in

...hat up, perhaps based on some DT > property, though I can already hear the NAK from DT maintainers because > this is, after all, policy, not hardware description. > > The last solution that I can think of that might allow us to do this is > to add a flag to struct device_driver (bool explicit_iommu?) that will > be used by the DMA/IOMMU setup code to decide whether or not to attach > to the IOMMU automatically. > > Though, again, I'm not sure that would actually solve your bank problem. > That's really something I don't see any other solution than to fix it in >...

From: Thierry Reding <treding at nvidia.com> Depending on the kernel configuration, early ARM architecture setup code may have attached the GPU to a DMA/IOMMU mapping that transparently uses the IOMMU to back the DMA API. Tegra requires special handling for IOMMU backed buffers (a special bit in the GPU's MMU page tables indicates the memory path to take: via the SMMU or directly to the