net: phy: Add phy library support to check supported list when autoneg is enabled

Adds support in phy library to accept autoneg configuration only when
feature is enabled in supported list.
Signed-off-by: Divya Koppera <divya.koppera@microchip.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://patch.msgid.link/20240821055906.27717-2-Divya.Koppera@microchip.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/phy/phy.c

@@ -1089,7 +1089,10 @@ int phy_ethtool_ksettings_set(struct phy_device *phydev,
 	if (autoneg != AUTONEG_ENABLE && autoneg != AUTONEG_DISABLE)
 		return -EINVAL;
 
-	if (autoneg == AUTONEG_ENABLE && linkmode_empty(advertising))
+	if (autoneg == AUTONEG_ENABLE &&
+	    (linkmode_empty(advertising) ||
+	     !linkmode_test_bit(ETHTOOL_LINK_MODE_Autoneg_BIT,
+				phydev->supported)))
 		return -EINVAL;
 
 	if (autoneg == AUTONEG_DISABLE &&