PCI: dpc: Increase pciehp waiting time for DPC recovery

zhaoxin inclusion
category: feature

--------------------

Commit a97396c ("PCI: pciehp: Ignore Link Down/Up caused by DPC")
amended PCIe hotplug to not bring down the slot upon Data Link Layer State
Changed events caused by Downstream Port Containment.

However, PCIe hotplug (pciehp) waits up to 4 seconds before assuming that
DPC recovery has failed and disabling the slot. This timeout period is
insufficient for some PCIe devices.
For example, the E810 dual-port network card driver needs to take over
10 seconds to execute its err_detected() callback.
Since this exceeds the maximum wait time allowed for DPC recovery by the
hotplug IRQ threads, a race condition occurs between the hotplug thread and
the dpc_handler() thread.

Signed-off-by: leoliu-oc <leoliu-oc@zhaoxin.com>

Author: leoliu-oc

drivers/pci/pcie/dpc.c

@@ -115,10 +115,10 @@ bool pci_dpc_recovered(struct pci_dev *pdev)
 	/*
 	 * Need a timeout in case DPC never completes due to failure of
 	 * dpc_wait_rp_inactive().  The spec doesn't mandate a time limit,
-	 * but reports indicate that DPC completes within 4 seconds.
+	 * but reports indicate that DPC completes within 16 seconds.
 	 */
 	wait_event_timeout(dpc_completed_waitqueue, dpc_completed(pdev),
-			   msecs_to_jiffies(4000));
+			   msecs_to_jiffies(16000));
 
 	return test_and_clear_bit(PCI_DPC_RECOVERED, &pdev->priv_flags);
 }