net: phy: marvell: Align set_loopback() implementation

Use genphy_loopback() to disable loopback like ksz9031_set_loopback().
This way disable loopback is implemented only once within
genphy_loopback() and the set_loopback() implementations look similar.

Also fix comment about msleep() in the out-of loopback case which is not
executed in the out-of loopback case.

Suggested-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Gerhard Engleder <gerhard@engleder-embedded.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://patch.msgid.link/20250312203010.47429-5-gerhard@engleder-embedded.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

drivers/net/phy/marvell.c

@@ -2133,56 +2133,50 @@ static void marvell_get_stats_simple(struct phy_device *phydev,
 
 static int m88e1510_loopback(struct phy_device *phydev, bool enable, int speed)
 {
+	u16 bmcr_ctl, mscr2_ctl = 0;
 	int err;
 
-	if (enable) {
-		u16 bmcr_ctl, mscr2_ctl = 0;
+	if (!enable)
+		return genphy_loopback(phydev, enable, 0);
 
-		if (speed == SPEED_10 || speed == SPEED_100 ||
-		    speed == SPEED_1000)
-			phydev->speed = speed;
-		else if (speed)
-			return -EINVAL;
-
-		bmcr_ctl = mii_bmcr_encode_fixed(phydev->speed, phydev->duplex);
-
-		err = phy_write(phydev, MII_BMCR, bmcr_ctl);
-		if (err < 0)
-			return err;
+	if (speed == SPEED_10 || speed == SPEED_100 || speed == SPEED_1000)
+		phydev->speed = speed;
+	else if (speed)
+		return -EINVAL;
 
-		if (phydev->speed == SPEED_1000)
-			mscr2_ctl = BMCR_SPEED1000;
-		else if (phydev->speed == SPEED_100)
-			mscr2_ctl = BMCR_SPEED100;
+	bmcr_ctl = mii_bmcr_encode_fixed(phydev->speed, phydev->duplex);
 
-		err = phy_modify_paged(phydev, MII_MARVELL_MSCR_PAGE,
-				       MII_88E1510_MSCR_2, BMCR_SPEED1000 |
-				       BMCR_SPEED100, mscr2_ctl);
-		if (err < 0)
-			return err;
+	err = phy_write(phydev, MII_BMCR, bmcr_ctl);
+	if (err < 0)
+		return err;
 
-		/* Need soft reset to have speed configuration takes effect */
-		err = genphy_soft_reset(phydev);
-		if (err < 0)
-			return err;
+	if (phydev->speed == SPEED_1000)
+		mscr2_ctl = BMCR_SPEED1000;
+	else if (phydev->speed == SPEED_100)
+		mscr2_ctl = BMCR_SPEED100;
 
-		err = phy_modify(phydev, MII_BMCR, BMCR_LOOPBACK,
-				 BMCR_LOOPBACK);
+	err = phy_modify_paged(phydev, MII_MARVELL_MSCR_PAGE,
+			       MII_88E1510_MSCR_2, BMCR_SPEED1000 |
+			       BMCR_SPEED100, mscr2_ctl);
+	if (err < 0)
+		return err;
 
-		if (!err) {
-			/* It takes some time for PHY device to switch
-			 * into/out-of loopback mode.
-			 */
-			msleep(1000);
-		}
+	/* Need soft reset to have speed configuration takes effect */
+	err = genphy_soft_reset(phydev);
+	if (err < 0)
 		return err;
-	} else {
-		err = phy_modify(phydev, MII_BMCR, BMCR_LOOPBACK, 0);
-		if (err < 0)
-			return err;
 
-		return phy_config_aneg(phydev);
+	err = phy_modify(phydev, MII_BMCR, BMCR_LOOPBACK,
+			 BMCR_LOOPBACK);
+
+	if (!err) {
+		/*
+		 * It takes some time for PHY device to switch into loopback
+		 * mode.
+		 */
+		msleep(1000);
 	}
+	return err;
 }
 
 static int marvell_vct5_wait_complete(struct phy_device *phydev)