iommu/arm-smmu-v3: Convert to use atomic poll timeout

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The arm_smmu_write_reg_sync() helper is currently implemented using
readl_relaxed_poll_timeout() (that relies on usleep_range() internally)
which becomes a critical issue when used in the gerror irq handler.

If the SMMU hits a gerror and enters Service Failure Mode
(GERROR_SFM_ERR), the gerror handler calls arm_smmu_device_disable() in
hard-irq context. This becomes a problem as arm_smmu_device_disable()
inevitably calls arm_smmu_write_reg_sync() which might attempt to sleep
inside a hard-irq context.

Fix this by converting the arm_smmu_write_reg_sync to use the
readl_relaxed_poll_timeout_atomic() polling helper.

(Discovered while running Sashiko locally on another patch series).

Reported-by: Sashiko <sashiko-bot@kernel.org>
Fixes: 48ec83bcbc ("iommu/arm-smmu: Add initial driver support for ARM SMMUv3 devices")
Signed-off-by: Pranjal Shrivastava <praan@google.com>
Signed-off-by: Will Deacon <will@kernel.org>

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Pranjal Shrivastava 2026-07-28 21:11:23 +00:00 • committed by Will Deacon

parent f99d3b4bb0

commit eced8058c8

1 changed files with 3 additions and 2 deletions

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drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c

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