[PATCH 2/4] PCI/portdrv: Don't require AER to bind DPC service

[Kuppuswamy Sathyanarayanan]

get_port_device_capability() binds the DPC service only if
pci_aer_available() is true.  pci_aer_available() is false with
"pci=noaer" or when MSI is disabled.

The DPC driver does not need either of these.  pci_aer_available()
depends on MSI only because the AER driver does not work with INTx
(commit 3e77a3f7895e ("PCI: Disable AER with pci=nomsi")).  The DPC
driver does not depend on MSI or on the AER driver, and it works on
ports without an AER capability.

PCIe r7.0 sec 6.2.11 recommends that the OS link control of DPC to
control of AER.  PCI Firmware r3.3, sec 4.5.2.4, requires the same for
_OSC.  Both are about ownership, not about using the AER driver.
host->native_aer and the _OSC negotiation already cover ownership.

Drop the pci_aer_available() check.

The changes in behavior are:

  - ACPI systems booted with "pci=noaer" or with MSI disabled, and with
    "pcie_ports=native" or "pcie_ports=dpc-native".  The OS now uses DPC
    there, which is what those options ask for.  Without them nothing
    changes, because the OS does not request AER control in _OSC, so
    host->native_aer is not set.

  - Non-ACPI systems booted with "pci=noaer" or with MSI disabled.
    host->native_aer is set there, so the OS now uses DPC.  An
    uncorrectable error that used to be ignored with "pci=noaer" now
    triggers DPC, which takes the link down and resets the devices below
    the port.

Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@xxxxxxxxxxxxxxx>
---
 drivers/pci/pcie/portdrv.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/drivers/pci/pcie/portdrv.c b/drivers/pci/pcie/portdrv.c
index 32fc623dd410..b77680fd3b75 100644
--- a/drivers/pci/pcie/portdrv.c
+++ b/drivers/pci/pcie/portdrv.c
@@ -263,7 +263,6 @@ static int get_port_device_capability(struct pci_dev *dev)
 	 * permission to use AER.
 	 */
 	if (pci_find_ext_capability(dev, PCI_EXT_CAP_ID_DPC) &&
-	    pci_aer_available() &&
 	    (pcie_ports_dpc_native || host->native_aer))
 		services |= PCIE_PORT_SERVICE_DPC;
 
-- 
2.43.0