On Tue, Sep 05, 2017 at 08:47:15PM +0800, Zhou Wang wrote: > On 2017/9/4 23:59, Lorenzo Pieralisi wrote: > > 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 > > Yes, DT also has this problem. > > > 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. > > I am not familiar with IORT init, but can we do it like: > > diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c > index a3215ee..a6f1a21 100644 > --- a/drivers/acpi/arm64/iort.c > +++ b/drivers/acpi/arm64/iort.c > @@ -1131,6 +1131,7 @@ static void __init iort_init_platform_devices(void) > acpi_free_fwnode_static(fwnode); > return; > } > + pci_request_acs(); > } > > iort_node = ACPI_ADD_PTR(struct acpi_iort_node, iort_node, > Yep, will send something similar shortly. Thanks, Lorenzo
