[PATCH next v1] r8169: Fix PHY lookup for mdiobus_get_phy() and improve error reporting during probe

[Anand Moon <linux.amoon@gmail.com>]

The driver currently assumes the PHY is always at address 0. On some
hardware or buggy BIOS implementations, the PHY may reside at a
different address on the MDIO bus. Update r8169_mdio_register()
to scan the bus for the first available PHY instead of hardcoding
address 0.

Additionally, switch to dev_err_probe() in the main probe path to
provide standardized error handling and cleaner log output for
registration failures.

Link: https://lore.kernel.org/all/87bc37ee-234c-4568-b72e-955c130a6838@arm.com/
Fixes: ec392abc9593 ("PCI: dw-rockchip: Enable async probe by default")
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: Danilo Krummrich <dakr@kernel.org>
Cc: Niklas Cassel <cassel@kernel.org>
Signed-off-by: Anand Moon <linux.amoon@gmail.com>
---
 drivers/net/ethernet/realtek/r8169_main.c | 34 ++++++++++++++++-------
 1 file changed, 24 insertions(+), 10 deletions(-)

diff --git a/drivers/net/ethernet/realtek/r8169_main.c b/drivers/net/ethernet/realtek/r8169_main.c
index 791277e750ba..0fd735beff92 100644
--- a/drivers/net/ethernet/realtek/r8169_main.c
+++ b/drivers/net/ethernet/realtek/r8169_main.c
@@ -5427,7 +5427,8 @@ static int r8169_mdio_register(struct rtl8169_private *tp)
 {
 	struct pci_dev *pdev = tp->pci_dev;
 	struct mii_bus *new_bus;
-	int ret;
+	struct phy_device *phydev;
+	int ret, addr;
 
 	/* On some boards with this chip version the BIOS is buggy and misses
 	 * to reset the PHY page selector. This results in the PHY ID read
@@ -5462,18 +5463,31 @@ static int r8169_mdio_register(struct rtl8169_private *tp)
 	if (ret)
 		return ret;
 
-	tp->phydev = mdiobus_get_phy(new_bus, 0);
-	if (!tp->phydev) {
+	/* find the first (lowest address) PHY on the current MAC's MII bus */
+	for (addr = 0; addr < PHY_MAX_ADDR; addr++) {
+		struct phy_device *tmp = mdiobus_get_phy(new_bus, addr);
+
+		if (tmp) {
+			phydev = tmp;
+			break;
+		}
+	}
+
+	if (!phydev) {
+		dev_err(&pdev->dev, "no PHY found on bus\n");
 		return -ENODEV;
-	} else if (!tp->phydev->drv) {
-		/* Most chip versions fail with the genphy driver.
-		 * Therefore ensure that the dedicated PHY driver is loaded.
-		 */
+	}
+
+	/* Most chip versions fail with the genphy driver.
+	 * Therefore ensure that the dedicated PHY driver is loaded.
+	 */
+	if (!phydev->drv) {
 		dev_err(&pdev->dev, "no dedicated PHY driver found for PHY ID 0x%08x, maybe realtek.ko needs to be added to initramfs?\n",
-			tp->phydev->phy_id);
+			phydev->phy_id);
 		return -EUNATCH;
 	}
 
+	tp->phydev = phydev;
 	tp->phydev->mac_managed_pm = true;
 	if (rtl_supports_eee(tp))
 		phy_support_eee(tp->phydev);
@@ -5790,11 +5804,11 @@ static int rtl_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
 
 	rc = r8169_mdio_register(tp);
 	if (rc)
-		return rc;
+		return dev_err_probe(&pdev->dev, rc, "mdio register failure\n");
 
 	rc = register_netdev(dev);
 	if (rc)
-		return rc;
+		return dev_err_probe(&pdev->dev, rc, "register newdev failure\n");
 
 	if (IS_ENABLED(CONFIG_R8169_LEDS)) {
 		if (rtl_is_8125(tp))

base-commit: 95c541ddfb0815a0ea8477af778bb13bb075079a
-- 
2.50.1