net: dsa: mv88e6xxx: Fix application of erratum 4.8 for 88E6393X

According to SERDES scripts for 88E6393X, erratum 4.8 has to be applied
every time before SerDes is powered on.

Split the code for erratum 4.8 into separate function and call it in
mv88e6393x_serdes_power().

Fixes: de776d0d ("net: dsa: mv88e6xxx: add support for mv88e6393x family")
Signed-off-by: Marek Behún <kabel@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/dsa/mv88e6xxx/serdes.c

@@ -1271,9 +1271,9 @@ void mv88e6390_serdes_get_regs(struct mv88e6xxx_chip *chip, int port, void *_p)
 	}
 }
 
-static int mv88e6393x_serdes_port_errata(struct mv88e6xxx_chip *chip, int lane)
+static int mv88e6393x_serdes_erratum_4_6(struct mv88e6xxx_chip *chip, int lane)
 {
-	u16 reg, pcs;
+	u16 reg;
 	int err;
 
 	/* mv88e6393x family errata 4.6:
@@ -1300,11 +1300,32 @@ static int mv88e6393x_serdes_port_errata(struct mv88e6xxx_chip *chip, int lane)
 		if (err)
 			return err;
 
-		err = mv88e6390_serdes_power_sgmii(chip, lane, false);
-		if (err)
-			return err;
+		return mv88e6390_serdes_power_sgmii(chip, lane, false);
 	}
 
+	return 0;
+}
+
+int mv88e6393x_serdes_setup_errata(struct mv88e6xxx_chip *chip)
+{
+	int err;
+
+	err = mv88e6393x_serdes_erratum_4_6(chip, MV88E6393X_PORT0_LANE);
+	if (err)
+		return err;
+
+	err = mv88e6393x_serdes_erratum_4_6(chip, MV88E6393X_PORT9_LANE);
+	if (err)
+		return err;
+
+	return mv88e6393x_serdes_erratum_4_6(chip, MV88E6393X_PORT10_LANE);
+}
+
+static int mv88e6393x_serdes_erratum_4_8(struct mv88e6xxx_chip *chip, int lane)
+{
+	u16 reg, pcs;
+	int err;
+
 	/* mv88e6393x family errata 4.8:
 	 * When a SERDES port is operating in 1000BASE-X or SGMII mode link may
 	 * not come up after hardware reset or software reset of SERDES core.
@@ -1334,29 +1355,21 @@ static int mv88e6393x_serdes_port_errata(struct mv88e6xxx_chip *chip, int lane)
 				      MV88E6393X_ERRATA_4_8_REG, reg);
 }
 
-int mv88e6393x_serdes_setup_errata(struct mv88e6xxx_chip *chip)
-{
-	int err;
-
-	err = mv88e6393x_serdes_port_errata(chip, MV88E6393X_PORT0_LANE);
-	if (err)
-		return err;
-
-	err = mv88e6393x_serdes_port_errata(chip, MV88E6393X_PORT9_LANE);
-	if (err)
-		return err;
-
-	return mv88e6393x_serdes_port_errata(chip, MV88E6393X_PORT10_LANE);
-}
-
 int mv88e6393x_serdes_power(struct mv88e6xxx_chip *chip, int port, int lane,
 			    bool on)
 {
 	u8 cmode = chip->ports[port].cmode;
+	int err;
 
 	if (port != 0 && port != 9 && port != 10)
 		return -EOPNOTSUPP;
 
+	if (on) {
+		err = mv88e6393x_serdes_erratum_4_8(chip, lane);
+		if (err)
+			return err;
+	}
+
 	switch (cmode) {
 	case MV88E6XXX_PORT_STS_CMODE_SGMII:
 	case MV88E6XXX_PORT_STS_CMODE_1000BASEX: