net: dsa: mv88e6xxx: correctly report serdes link failure

Phylink wants to know if the link has dropped since the last time state
was retrieved, and the BMSR gives us that. Read the BMSR and use it when
deciding the link state. Fill in the an_complete member as well for the
emulated PHY state.
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/dsa/mv88e6xxx/serdes.c

@@ -53,6 +53,14 @@ static int mv88e6xxx_serdes_pcs_get_state(struct mv88e6xxx_chip *chip,
 					  u16 bmsr, u16 lpa, u16 status,
 					  struct phylink_link_state *state)
 {
+	state->link = false;
+
+	/* If the BMSR reports that the link had failed, report this to
+	 * phylink.
+	 */
+	if (!(bmsr & BMSR_LSTATUS))
+		return 0;
+
 	state->link = !!(status & MV88E6390_SGMII_PHY_STATUS_LINK);
 	state->an_complete = !!(bmsr & BMSR_ANEGCOMPLETE);