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, Best, Zhou > > Lorenzo > > . >
