tsnep: Select speed for loopback

Use 100 Mbps only if the PHY is configured to this speed. Otherwise use
always the maximum speed of 1000 Mbps.

Also remove explicit setting of carrier on and link mode after loopback.
This is not needed anymore, because phy_loopback() with selected speed
signals the link and the speed to the MAC.

Signed-off-by: Gerhard Engleder <gerhard@engleder-embedded.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://patch.msgid.link/20250312203010.47429-6-gerhard@engleder-embedded.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

drivers/net/ethernet/engleder/tsnep_main.c

@@ -221,20 +221,19 @@ static void tsnep_phy_link_status_change(struct net_device *netdev)
 
 static int tsnep_phy_loopback(struct tsnep_adapter *adapter, bool enable)
 {
-	int retval;
-
-	retval = phy_loopback(adapter->phydev, enable, 0);
+	int speed;
 
-	/* PHY link state change is not signaled if loopback is enabled, it
-	 * would delay a working loopback anyway, let's ensure that loopback
-	 * is working immediately by setting link mode directly
-	 */
-	if (!retval && enable) {
-		netif_carrier_on(adapter->netdev);
-		tsnep_set_link_mode(adapter);
+	if (enable) {
+		if (adapter->phydev->autoneg == AUTONEG_DISABLE &&
+		    adapter->phydev->speed == SPEED_100)
+			speed = SPEED_100;
+		else
+			speed = SPEED_1000;
+	} else {
+		speed = 0;
 	}
 
-	return retval;
+	return phy_loopback(adapter->phydev, enable, speed);
 }
 
 static int tsnep_phy_open(struct tsnep_adapter *adapter)