search for: of_dma_configure

...hing to struct device that could be used by arch_setup_dma_ops() to not attach any of the IOMMU-backed DMA operations to the device. Unfortunately that code is called before the driver's ->probe() implementation is called, so a driver doesn't have an opportunity to set it. Something like of_dma_configure() 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 expl...

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

...e that could be used by arch_setup_dma_ops() to not attach any of > the IOMMU-backed DMA operations to the device. Unfortunately that code > is called before the driver's ->probe() implementation is called, so a > driver doesn't have an opportunity to set it. Something like > of_dma_configure() 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...

Hello, There is a trouble on ARM with DMA allocations made by device drivers, the trouble is that DMA allocations are getting implicitly backed with IOMMU mapping by the driver core if IOMMU presents in a system and IOMMU could handle device. This is an undesired behaviour for drivers that manage IOMMU by themselves, like NVIDIA Tegra GPU driver. On arm32 the implicit backing happens if

On Tue, May 05, 2020 at 03:00:04PM +0530, Bharat Bhushan wrote: > Different endpoint can support different page size, probe > endpoint if it supports specific page size otherwise use > global page sizes. > > Signed-off-by: Bharat Bhushan <bbhushan2 at marvell.com> > --- > v4->v5: > - Rebase to Linux v5.7-rc4 > > v3->v4: > - Fix whitespace error >

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