Re: [PATCH v8 3/4] iommu/arm-smmu-v3: Standardize ATS enablement failure reporting

[Samiullah Khawaja <skhawaja@google.com>]

On Thu, Jun 04, 2026 at 06:21:15PM +0000, Pranjal Shrivastava wrote:
>Update arm_smmu_enable_ats() to wrap the pci_enable_ats() call in
>WARN_ON(). Since probe-time checks now preclude configuration errors
>any failure during hardware enablement is considered a kernel bug.
>
>Reviewed-by: Kevin Tian <kevin.tian@intel.com>
>Signed-off-by: Pranjal Shrivastava <praan@google.com>
>---
> drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 7 ++++++-
> 1 file changed, 6 insertions(+), 1 deletion(-)
>
>diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
>index a10affb483a4..0494c68daa19 100644
>--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
>+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
>@@ -2956,7 +2956,12 @@ static void arm_smmu_enable_ats(struct arm_smmu_master *master)
> 	 * ATC invalidation of PASID 0 causes the entire ATC to be flushed.
> 	 */
> 	arm_smmu_atc_inv_master(master, IOMMU_NO_PASID);
>-	if (pci_enable_ats(pdev, stu))
>+
>+	 /*
>+	  * Since pci_prepare_ats() has already verified the HW capability
>+	  * and programmed the STE, pci_enable_ats() should not fail here.
>+	  */
>+	if (WARN_ON(pci_enable_ats(pdev, stu)))
> 		dev_err(master->dev, "Failed to enable ATS (STU %zu)\n", stu);
> }
>
>-- 
>2.54.0.1032.g2f8565e1d1-goog
>

Reviewed-by: Samiullah Khawaja <skhawaja@google.com>