PCI/portdrv: Report reset for frozen channel

The PCI error recovery always resets the link for a frozen state, so the
port driver should return that a reset is required for its result. This
will get the .slot_reset() callback invoked, which is necessary to
restore the port's config space. Without this, the driver had been
relying on downstream drivers to return this status.

Link: https://lore.kernel.org/r/20210104230300.1277180-6-kbusch@kernel.orgTested-by: Hedi Berriche <hedi.berriche@hpe.com>
Signed-off-by: Keith Busch <kbusch@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Hedi Berriche <hedi.berriche@hpe.com>

drivers/pci/pcie/portdrv_pci.c

@@ -153,7 +153,8 @@ static void pcie_portdrv_remove(struct pci_dev *dev)
 static pci_ers_result_t pcie_portdrv_error_detected(struct pci_dev *dev,
 					pci_channel_state_t error)
 {
-	/* Root Port has no impact. Always recovers. */
+	if (error == pci_channel_io_frozen)
+		return PCI_ERS_RESULT_NEED_RESET;
 	return PCI_ERS_RESULT_CAN_RECOVER;
 }