On Sun, Jan 12, 2020 at 02:44:02PM -0800, sathyanarayanan.kuppuswamy@xxxxxxxxxxxxxxx wrote: > From: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@xxxxxxxxxxxxxxx> > > As per PCI firmware specification r3.2 Downstream Port Containment > Related Enhancements ECN, sec 4.5.1, OS must implement following steps > to enable/use EDR feature. > > 1. OS can use bit 7 of _OSC Control Field to negotiate control over > Downstream Port Containment (DPC) configuration of PCIe port. After _OSC > negotiation, firmware will Set this bit to grant OS control over PCIe > DPC configuration and Clear it if this feature was requested and denied, > or was not requested. > > 2. Also, if OS supports EDR, it should expose its support to BIOS by > setting bit 7 of _OSC Support Field. And if OS sets bit 7 of _OSC > Control Field it must also expose support for EDR by setting bit 7 of > _OSC Support Field. > --- a/drivers/pci/pcie/portdrv_core.c > +++ b/drivers/pci/pcie/portdrv_core.c > @@ -253,10 +253,13 @@ static int get_port_device_capability(struct pci_dev *dev) > /* > * With dpc-native, allow Linux to use DPC even if it doesn't have > * permission to use AER. > + * If EDR support is enabled in OS, then even if AER is not handled in > + * OS, DPC service can be enabled. Can you clarify this comment? It talks about AER, but the code you added: (IS_ENABLED(CONFIG_PCIE_EDR) && !host->native_dpc) doesn't have anything to do with AER. > */ > if (pci_find_ext_capability(dev, PCI_EXT_CAP_ID_DPC) && > - pci_aer_available() && > - (pcie_ports_dpc_native || (services & PCIE_PORT_SERVICE_AER))) > + ((IS_ENABLED(CONFIG_PCIE_EDR) && !host->native_dpc) || > + (pci_aer_available() && > + (pcie_ports_dpc_native || (services & PCIE_PORT_SERVICE_AER))))) > services |= PCIE_PORT_SERVICE_DPC;
