diff --git a/drivers/net/ethernet/broadcom/genet/bcmmii.c b/drivers/net/ethernet/broadcom/genet/bcmmii.c
index 51f6c94e919e..6d823c107476 100644
--- a/drivers/net/ethernet/broadcom/genet/bcmmii.c
+++ b/drivers/net/ethernet/broadcom/genet/bcmmii.c
@@ -264,6 +264,7 @@ int bcmgenet_mii_config(struct net_device *dev, bool init)
 	 * block for the interface to work
 	 */
 	if (priv->ext_phy) {
+		mutex_lock(&phydev->lock);
 		reg = bcmgenet_ext_readl(priv, EXT_RGMII_OOB_CTRL);
 		reg &= ~ID_MODE_DIS;
 		reg |= id_mode_dis;
@@ -272,6 +273,7 @@ int bcmgenet_mii_config(struct net_device *dev, bool init)
 		else
 			reg |= RGMII_MODE_EN;
 		bcmgenet_ext_writel(priv, reg, EXT_RGMII_OOB_CTRL);
+		mutex_unlock(&phydev->lock);
 	}
 
 	if (init)