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iommu/arm-smmu-v3: Enable CFGI/TLBI-repeat workaround on Tegra264

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Nvidia Tegra264 SMMU is affected by an erratum where a TLB entry can
survive an invalidation that races with concurrent traffic targeting
the same entry. The hardware-recommended software workaround is to
issue every CFGI/TLBI command (each followed by CMD_SYNC) twice, and
that infrastructure is already in place behind
arm_smmu_erratum_repeat_tlbi_cfgi_key.

Neither IDR nor IIDR flags this Tegra264-specific bug, so hardware
detection is not possible. Tegra264 is device-tree-only (no ACPI/IORT
support) and already has a dedicated "nvidia,tegra264-smmu" compatible,
so DT-probe is the only viable detection path.

Enable the workaround on instances matching the existing
"nvidia,tegra264-smmu" compatible by calling static_branch_enable() on
arm_smmu_erratum_repeat_tlbi_cfgi_key. Document the erratum in
Documentation/arch/arm64/silicon-errata.rst.

Signed-off-by: Ashish Mhetre <amhetre@nvidia.com>
Reviewed-by: Nicolin Chen <nicolinc@nvidia.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Will Deacon <will@kernel.org>
This commit is contained in:
Ashish Mhetre 2026-07-26 08:19:04 +00:00 committed by Will Deacon
parent d501d66815
commit 06b15ddcfb
2 changed files with 5 additions and 1 deletions
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2
Documentation/arch/arm64/silicon-errata.rst
View File

@ -312,6 +312,8 @@ stable kernels.
| | | T241-MPAM-4, | |
| | | T241-MPAM-6 | |
+----------------+-----------------+-----------------+-----------------------------+
| NVIDIA | T264 SMMU | T264-SMMU-3 | N/A |
+----------------+-----------------+-----------------+-----------------------------+
+----------------+-----------------+-----------------+-----------------------------+
| Freescale/NXP | LS2080A/LS1043A | A-008585 | FSL_ERRATUM_A008585 |
+----------------+-----------------+-----------------+-----------------------------+

4
drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
View File

@ -5386,8 +5386,10 @@ static int arm_smmu_device_dt_probe(struct platform_device *pdev,
if (of_dma_is_coherent(dev->of_node))
smmu->features |= ARM_SMMU_FEAT_COHERENCY;
if (of_device_is_compatible(dev->of_node, "nvidia,tegra264-smmu"))
if (of_device_is_compatible(dev->of_node, "nvidia,tegra264-smmu")) {
tegra_cmdqv_dt_probe(dev->of_node, smmu);
static_branch_enable(&arm_smmu_erratum_repeat_tlbi_cfgi_key);
}
return ret;
}