On Mon, Sep 04, 2017 at 08:33:22PM +0800, Zhou Wang wrote: > +to: Lorenzo > > On 2017/8/31 22:21, Zhou Wang wrote: > > Hi Will and Alex, > > > > pci_request_acs is called in drivers/iommu/arm-smmu-v3.c to set pci_acs_enable. > > > > PCI subsystem tries to enable ACS as below: > > > > pci_device_add > > --> pci_init_capabilities > > --> pci_enable_acs > > > > in ACPI PCI driver. However, ACPI PCI driver will be called before SMMU v3 driver, > > which will lead pci_enable_acs to return directly as pci_acs_enable is not set > > before SMMU v3 driver loading. > > > > I think this is a bug, what do you think about this problem? I think that it is a bug that affects OF/ACPI alike. One way of solving it is requesting ACS at IORT init following appropriate checks (ie mappings PCI->IOMMU - that would not solve the OF path though). I can put together a quick fix, the overall problem needs some thinking though. Lorenzo
