Re: [PATCH v6 12/25] iommu/tegra-smmu: Support DMA domains in tegra
From: Baolu Lu <baolu.lu@linux.intel.com>
Date: 2023-08-14 05:09:30
Also in:
linux-arm-kernel, linux-arm-msm, linux-iommu, linux-mediatek, linux-rockchip, linux-s390, linux-samsung-soc, linux-sunxi, linux-tegra
On 2023/8/3 8:07, Jason Gunthorpe wrote:
quoted hunk ↗ jump to hunk
All ARM64 iommu drivers should support IOMMU_DOMAIN_DMA to enable dma-iommu.c. tegra is blocking dma-iommu usage, and also default_domain's, because it wants an identity translation. This is needed for some device quirk. The correct way to do this is to support IDENTITY domains and use ops->def_domain_type() to return IOMMU_DOMAIN_IDENTITY for only the quirky devices. Add support for IOMMU_DOMAIN_DMA and force IOMMU_DOMAIN_IDENTITY mode for everything so no behavior changes. Signed-off-by: Jason Gunthorpe <jgg@nvidia.com> --- drivers/iommu/tegra-smmu.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-)diff --git a/drivers/iommu/tegra-smmu.c b/drivers/iommu/tegra-smmu.c index f63f1d4f0bd10f..6cba034905edbf 100644 --- a/drivers/iommu/tegra-smmu.c +++ b/drivers/iommu/tegra-smmu.c@@ -276,7 +276,7 @@ static struct iommu_domain *tegra_smmu_domain_alloc(unsigned type) { struct tegra_smmu_as *as; - if (type != IOMMU_DOMAIN_UNMANAGED) + if (type != IOMMU_DOMAIN_UNMANAGED && type != IOMMU_DOMAIN_DMA) return NULL; as = kzalloc(sizeof(*as), GFP_KERNEL);@@ -989,6 +989,12 @@ static int tegra_smmu_def_domain_type(struct device *dev) } static const struct iommu_ops tegra_smmu_ops = { + /* + * FIXME: For now we want to run all translation in IDENTITY mode, + * better would be to have a def_domain_type op do this for just the + * quirky device. + */ + .default_domain = &tegra_smmu_identity_domain,
tegra_smmu_def_domain_type() has already forced the core to use ops->identity_domain, why do we still need ops->default_domain?
.identity_domain = &tegra_smmu_identity_domain, .def_domain_type = &tegra_smmu_def_domain_type, .domain_alloc = tegra_smmu_domain_alloc,
Best regards, baolu