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It doesn't > declare any fixups, e.g., DECLARE_PCI_FIXUP_FINAL, and it doesn't > update any state cached by the PCI core. It works like the acs quirks that are in the quirks file, which are also arguably only used by iommu too :) I'm not keen on spreading lists of device ids for PCI quirks to iommu files, but it would be OK to move pci_ats_always_on() to iommu_ats_always_on() that calls the PCI quirk function. Thanks, Jason