diff --git a/drivers/net/dsa/microchip/ksz_common.c b/drivers/net/dsa/microchip/ksz_common.c
index 0f02c62b0268..c9389880ad1f 100644
--- a/drivers/net/dsa/microchip/ksz_common.c
+++ b/drivers/net/dsa/microchip/ksz_common.c
@@ -453,9 +453,15 @@ void ksz_phylink_get_caps(struct dsa_switch *ds, int port,
 	if (dev->info->supports_rgmii[port])
 		phy_interface_set_rgmii(config->supported_interfaces);
 
-	if (dev->info->internal_phy[port])
+	if (dev->info->internal_phy[port]) {
 		__set_bit(PHY_INTERFACE_MODE_INTERNAL,
 			  config->supported_interfaces);
+		/* Compatibility for phylib's default interface type when the
+		 * phy-mode property is absent
+		 */
+		__set_bit(PHY_INTERFACE_MODE_GMII,
+			  config->supported_interfaces);
+	}
 
 	if (dev->dev_ops->get_caps)
 		dev->dev_ops->get_caps(dev, port, config);