Rockchip Ethernet "Cannot attach to PHY (error: -19)": Fix

Symptoms

• ip link set eth0 up fails, and dmesg shows "Cannot attach to PHY (error: -19)"
• No PHY ID under /sys/bus/mdio_bus/devices

Common causes

• PHY held in reset: wrong reset GPIO, polarity or too-short reset delays
• PHY unpowered or missing its 25 MHz crystal
• Wrong PHY address (reg) vs hardware straps
• MDIO/MDC pinctrl not applied
• phy-handle points at the wrong node

How to fix it

1. See what the MDIO bus found

   dmesg | grep -iE 'stmmac|dwmac|mdio|phy'
   cat /sys/bus/mdio_bus/devices/*/phy_id 2>/dev/null

2. Fix reset timing and address

   &mdio0 {
       rgmii_phy: ethernet-phy@1 {
           compatible = "ethernet-phy-ieee802.3-c22";
           reg = <0x1>;              /* must match PHY address straps */
           reset-gpios = <&gpio4 RK_PB3 GPIO_ACTIVE_LOW>;
           reset-assert-us = <20000>;
           reset-deassert-us = <100000>;
       };
   };

3. Measure the hardware

   Check PHY supply rails and the 25 MHz clock with a scope; confirm the reset line toggles at boot.

Go deeper

• Rockchip Ethernet PHY Debugging: RGMII Delays, MDIO and Link Problems

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