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SubjectRe: [PATCH v12 8/8] PCI/ACPI: Enable EDR support
On Sun, Jan 12, 2020 at 02:44:02PM -0800, sathyanarayanan.kuppuswamy@linux.intel.com wrote:
> From: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
>
> 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;

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