Merge branch 'net-enetc-fix-fallback-phy-address-handling-and-do-not-skip-setting-for-addr-0'

Wei Fang says:

====================
net: enetc: fix fallback PHY address handling and do not skip setting for addr 0

There are two potential issues when PHY address 0 is used on the board,
see the commit messages of the patches for more details.

v1: https://lore.kernel.org/imx/20260303103047.228005-1-wei.fang@nxp.com/
====================

Link: https://patch.msgid.link/20260305031211.904812-1-wei.fang@nxp.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

Author: Paolo Abeni

drivers/net/ethernet/freescale/enetc/netc_blk_ctrl.c

@@ -333,11 +333,13 @@ static int netc_get_phy_addr(struct device_node *np)
 
 	mdio_node = of_get_child_by_name(np, "mdio");
 	if (!mdio_node)
-		return 0;
+		return -ENODEV;
 
 	phy_node = of_get_next_child(mdio_node, NULL);
-	if (!phy_node)
+	if (!phy_node) {
+		err = -ENODEV;
 		goto of_put_mdio_node;
+	}
 
 	err = of_property_read_u32(phy_node, "reg", &addr);
 	if (err)
@@ -423,6 +425,9 @@ static int imx95_enetc_mdio_phyaddr_config(struct platform_device *pdev)
 
 			addr = netc_get_phy_addr(gchild);
 			if (addr < 0) {
+				if (addr == -ENODEV)
+					continue;
+
 				dev_err(dev, "Failed to get PHY address\n");
 				return addr;
 			}
@@ -433,12 +438,6 @@ static int imx95_enetc_mdio_phyaddr_config(struct platform_device *pdev)
 				return -EINVAL;
 			}
 
-			/* The default value of LaBCR[MDIO_PHYAD_PRTAD ] is
-			 * 0, so no need to set the register.
-			 */
-			if (!addr)
-				continue;
-
 			switch (bus_devfn) {
 			case IMX95_ENETC0_BUS_DEVFN:
 				netc_reg_write(priv->ierb, IERB_LBCR(0),
@@ -578,16 +577,13 @@ static int imx94_enetc_mdio_phyaddr_config(struct netc_blk_ctrl *priv,
 
 	addr = netc_get_phy_addr(np);
 	if (addr < 0) {
+		if (addr == -ENODEV)
+			return 0;
+
 		dev_err(dev, "Failed to get PHY address\n");
 		return addr;
 	}
 
-	/* The default value of LaBCR[MDIO_PHYAD_PRTAD] is 0,
-	 * so no need to set the register.
-	 */
-	if (!addr)
-		return 0;
-
 	if (phy_mask & BIT(addr)) {
 		dev_err(dev,
 			"Find same PHY address in EMDIO and ENETC node\n");