net: phy: dp83tg720: wake up PHYs in managed mode

In case this PHY is bootstrapped for managed mode, we need to manually
wake it. Otherwise no link will be detected.

Cc: stable@vger.kernel.org
Fixes: cb80ee2 ("net: phy: Add support for the DP83TG720S Ethernet PHY")
Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Link: https://lore.kernel.org/r/20240614094516.1481231-1-o.rempel@pengutronix.de
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/phy/dp83tg720.c

@@ -17,6 +17,11 @@
 #define DP83TG720S_PHY_RESET			0x1f
 #define DP83TG720S_HW_RESET			BIT(15)
 
+#define DP83TG720S_LPS_CFG3			0x18c
+/* Power modes are documented as bit fields but used as values */
+/* Power Mode 0 is Normal mode */
+#define DP83TG720S_LPS_CFG3_PWR_MODE_0		BIT(0)
+
 #define DP83TG720S_RGMII_DELAY_CTRL		0x602
 /* In RGMII mode, Enable or disable the internal delay for RXD */
 #define DP83TG720S_RGMII_RX_CLK_SEL		BIT(1)
@@ -154,10 +159,17 @@ static int dp83tg720_config_init(struct phy_device *phydev)
 	 */
 	usleep_range(1000, 2000);
 
-	if (phy_interface_is_rgmii(phydev))
-		return dp83tg720_config_rgmii_delay(phydev);
+	if (phy_interface_is_rgmii(phydev)) {
+		ret = dp83tg720_config_rgmii_delay(phydev);
+		if (ret)
+			return ret;
+	}
 
-	return 0;
+	/* In case the PHY is bootstrapped in managed mode, we need to
+	 * wake it.
+	 */
+	return phy_write_mmd(phydev, MDIO_MMD_VEND2, DP83TG720S_LPS_CFG3,
+			     DP83TG720S_LPS_CFG3_PWR_MODE_0);
 }
 
 static struct phy_driver dp83tg720_driver[] = {