e1000: Recover from the 82574 PHY hang

The shared code provides e1000_check_phy_82574() to recognize a PHY
hang from saturated receive error and idle error counters, but em(4)
never calls it.

Run the check from timer driven admin work.  Match Intel e1000e by
requiring two consecutive positive samples before requesting a full
iflib reset.

MFC after:	2 weeks
Sponsored by:	BBOX.io

2 files changed, 25 insertions, 1 deletions

diff --git a/sys/dev/e1000/if_em.c b/sys/dev/e1000/if_em.c
index 6574b2d0e7d7..f07f75100650 100644
--- a/sys/dev/e1000/if_em.c
+++ b/sys/dev/e1000/if_em.c
@@ -3447,8 +3447,30 @@ em_if_update_admin_status(if_ctx_t ctx)
 	 * message.  Exported counters can consequently trail hardware by the
 	 * timer interval (normally 500 ms).
 	 */
-	if (atomic_readandclear_32(&sc->stats_pending) != 0)
+	if (atomic_readandclear_32(&sc->stats_pending) != 0) {
 		em_update_stats_counters(sc);
+		/*
+		 * The 82574 PHY can enter a state in which both its receive
+		 * error and idle error counters saturate.  Require two
+		 * consecutive timer samples before resetting, matching Intel's
+		 * e1000e recovery policy and avoiding a reset on a transient
+		 * register sample.
+		 */
+		if (hw->mac.type == e1000_82574) {
+			if (e1000_check_phy_82574(hw))
+				sc->phy_hang_count++;
+			else
+				sc->phy_hang_count = 0;
+			if (sc->phy_hang_count > 1) {
+				sc->phy_hang_count = 0;
+				device_printf(dev,
+				    "PHY appears hung; requesting reset\n");
+				iflib_request_reset(ctx);
+				iflib_admin_intr_deferred(ctx);
+				return;
+			}
+		}
+	}
 
 	/* Reset LAA into RAR[0] on 82571 */
 	if (hw->mac.type == e1000_82571 && e1000_get_laa_state_82571(hw))
@@ -4511,6 +4533,7 @@ em_reset(if_ctx_t ctx)
 	E1000_WRITE_REG(hw, E1000_VET, ETHERTYPE_VLAN);
 	e1000_get_phy_info(hw);
 	e1000_check_for_link(hw);
+	sc->phy_hang_count = 0;
 
 	return (E1000_SUCCESS);
 }
diff --git a/sys/dev/e1000/if_em.h b/sys/dev/e1000/if_em.h
index 9c441edd320b..e5b0fec8b087 100644
--- a/sys/dev/e1000/if_em.h
+++ b/sys/dev/e1000/if_em.h
@@ -622,6 +622,7 @@ struct e1000_softc {
 	u32			pba;
 	int			link_mask;
 	int			tso_automasked;
+	u32			phy_hang_count;
 	u32			promisc_pending;
 	u32			stats_pending;
 	u32			fatal_error_state;