Re: [PATCH v6 06/25] iommu/tegra-gart: Remove tegra-gart

Baolu Lu
2023-08-12T01:52:07Z

On 2023/8/3 8:07, Jason Gunthorpe wrote:
> Thierry says this is not used anymore, and doesn't think it makes sense as
> an iommu driver. The HW it supports is about 10 years old now and newer HW
> uses different IOMMU drivers.
>
> As this is the only driver with a GART approach, and it doesn't really
> meet the driver expectations from the IOMMU core, let's just remove it
> so we don't have to think about how to make it fit in.
>
> It has a number of identified problems:
> - The assignment of iommu_groups doesn't match the HW behavior
>
> - It claims to have an UNMANAGED domain but it is really an IDENTITY
> domain with a translation aperture. This is inconsistent with the core
> expectation for security sensitive operations
>
> - It doesn't implement a SW page table under struct iommu_domain so
> * It can't accept a map until the domain is attached
> * It forgets about all maps after the domain is detached
> * It doesn't clear the HW of maps once the domain is detached
> (made worse by having the wrong groups)
>
> Cc: Thierry Reding<treding@nvidia.com>
> Cc: Dmitry Osipenko<digetx@gmail.com>
> Acked-by: Thierry Reding<treding@nvidia.com>
> Signed-off-by: Jason Gunthorpe<jgg@nvidia.com>
> ---
> arch/arm/configs/multi_v7_defconfig | 1 -
> arch/arm/configs/tegra_defconfig | 1 -
> drivers/iommu/Kconfig | 11 -
> drivers/iommu/Makefile | 1 -
> drivers/iommu/tegra-gart.c | 371 ----------------------------
> drivers/memory/tegra/mc.c | 34 ---
> drivers/memory/tegra/tegra20.c | 28 ---
> include/soc/tegra/mc.h | 26 --
> 8 files changed, 473 deletions(-)
> delete mode 100644 drivers/iommu/tegra-gart.c

Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>

Best regards,
baolu