phb4: Use link if degraded

In the recent change:
 3f936ba phb4: Retrain link if degraded
We retrain if the link is degraded.  We do 3 retries to get an optimal
link.

Unfortunately if the last retry fails, we mark the PHB as bad and
don't use it. Hence that PHB is lost even though it actually trained
(just degraded).

This fixes the problem by printing an error message (as below) but
still marking the PHB as good.

  [    7.179320404,3] PHB#0005[0:5]: LINK: Link degraded
  [    8.387346665,3] PHB#0005[0:5]: LINK: Link degraded
  [   10.078409137,3] PHB#0005[0:5]: LINK: Link degraded
  [   11.281477269,3] PHB#0005[0:5]: LINK: Link degraded
  [   11.283123885,3] PHB#0005[0:5]: LINK: Degraded but no more retries

Signed-off-by: Michael Neuling <mikey@neuling.org>
Acked-by: Russell Currey <ruscur@russell.cc>
Signed-off-by: Stewart Smith <stewart@linux.vnet.ibm.com>

hw/phb4.c

@@ -2622,7 +2622,13 @@ static int64_t phb4_poll_link(struct pci_slot *slot)
 			PHBDBG(p, "LINK: Link is stable\n");
 			if (!phb4_link_optimal(slot)) {
 				PHBERR(p, "LINK: Link degraded\n");
-				return phb4_retry_state(slot);
+				if (slot->link_retries)
+					return phb4_retry_state(slot);
+				/*
+				 * Link is degraded but no more retries, so
+				 * settle for what we have :-(
+				 */
+				PHBERR(p, "LINK: Degraded but no more retries\n");
 			}
 			pci_slot_set_state(slot, PHB4_SLOT_NORMAL);
 			return OPAL_SUCCESS;