net: stmmac: check fwnode for phy device before scanning for phy

Some DT devices already have phy device configured in the DT/ACPI.
Current implementation scans for a phy unconditionally even though
there is a phy listed in the DT/ACPI and already attached.

We should check the fwnode if there is any phy device listed in
fwnode and decide whether to scan for a phy to attach to.

Fixes: fe2cfbc968 ("net: stmmac: check if MAC needs to attach to a PHY")
Reported-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Link: https://lore.kernel.org/lkml/20230403212434.296975-1-martin.blumenstingl@googlemail.com/
Tested-by: Guenter Roeck <linux@roeck-us.net>
Tested-by: Shahab Vahedi <shahab@synopsys.com>
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Tested-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Suggested-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Signed-off-by: Michael Sit Wei Hong <michael.wei.hong.sit@intel.com>
Link: https://lore.kernel.org/r/20230406024541.3556305-1-michael.wei.hong.sit@intel.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/stmicro/stmmac/stmmac_main.c

@@ -1134,22 +1134,26 @@ static void stmmac_check_pcs_mode(struct stmmac_priv *priv)
 static int stmmac_init_phy(struct net_device *dev)
 {
 	struct stmmac_priv *priv = netdev_priv(dev);
+	struct fwnode_handle *phy_fwnode;
 	struct fwnode_handle *fwnode;
-	bool phy_needed;
 	int ret;
 
+	if (!phylink_expects_phy(priv->phylink))
+		return 0;
+
 	fwnode = of_fwnode_handle(priv->plat->phylink_node);
 	if (!fwnode)
 		fwnode = dev_fwnode(priv->device);
 
 	if (fwnode)
-		ret = phylink_fwnode_phy_connect(priv->phylink, fwnode, 0);
+		phy_fwnode = fwnode_get_phy_node(fwnode);
+	else
+		phy_fwnode = NULL;
 
-	phy_needed = phylink_expects_phy(priv->phylink);
 	/* Some DT bindings do not set-up the PHY handle. Let's try to
 	 * manually parse it
 	 */
-	if (!fwnode || phy_needed || ret) {
+	if (!phy_fwnode || IS_ERR(phy_fwnode)) {
 		int addr = priv->plat->phy_addr;
 		struct phy_device *phydev;
 
@@ -1165,6 +1169,9 @@ static int stmmac_init_phy(struct net_device *dev)
 		}
 
 		ret = phylink_connect_phy(priv->phylink, phydev);
+	} else {
+		fwnode_handle_put(phy_fwnode);
+		ret = phylink_fwnode_phy_connect(priv->phylink, fwnode, 0);
 	}
 
 	if (!priv->plat->pmt) {