Index: linux-5.4.124/drivers/net/dsa/mt7530.c
===================================================================
--- linux-5.4.124.orig/drivers/net/dsa/mt7530.c
+++ linux-5.4.124/drivers/net/dsa/mt7530.c
@@ -1021,6 +1021,9 @@ mt7530_stp_state_set(struct dsa_switch *
 	struct mt7530_priv *priv = ds->priv;
 	u32 stp_state;
 
+	if (dsa_is_unused_port(ds, port))
+		return;
+
 	switch (state) {
 	case BR_STATE_DISABLED:
 		stp_state = MT7530_STP_DISABLED;
@@ -1676,10 +1679,58 @@ mt7530_setup(struct dsa_switch *ds)
 }
 
 static int
+setup_unused_ports(struct dsa_switch *ds, u32 pm)
+{
+	struct mt7530_priv *priv = ds->priv;
+	u32 egtag_mask = 0;
+	u32 egtag_val = 0;
+	int i;
+
+	if (!pm)
+		return 0;
+
+	for (i = 0; i < MT7530_NUM_PORTS; i++) {
+		if (!dsa_is_unused_port(ds, i))
+			continue;
+
+		/* Setup MAC port with maximum capability. */
+		if ((i == 5) || (i == 6))
+			if (priv->info->cpu_port_config)
+				priv->info->cpu_port_config(ds, i);
+
+		mt7530_rmw(priv, MT7530_PCR_P(i), PCR_MATRIX_MASK | PCR_PORT_VLAN_MASK,
+			   PCR_MATRIX(pm) | MT7530_PORT_SECURITY_MODE);
+		egtag_mask |= ETAG_CTRL_P_MASK(i);
+		egtag_val |=  ETAG_CTRL_P(i, MT7530_VLAN_EGRESS_UNTAG);
+	}
+
+	/* Add unused ports to VLAN2 group for using IVL fdb. */
+	mt7530_write(priv, MT7530_VAWD1,
+		     IVL_MAC | VTAG_EN | PORT_MEM(pm) | VLAN_VALID);
+	mt7530_rmw(priv, MT7530_VAWD2, egtag_mask, egtag_val);
+	mt7530_vlan_cmd(priv, MT7530_VTCR_WR_VID, MT753X_RESERVED_VLAN);
+
+	for (i = 0; i < MT7530_NUM_PORTS; i++) {
+		if (!dsa_is_unused_port(ds, i))
+			continue;
+
+		mt7530_rmw(priv, MT7530_PPBV1_P(i), G0_PORT_VID_MASK,
+			   G0_PORT_VID(MT753X_RESERVED_VLAN));
+		mt7530_rmw(priv, MT7530_SSP_P(i), FID_PST_MASK, MT7530_STP_FORWARDING);
+
+		dev_dbg(ds->dev, "Add unused port%d to reserved VLAN%d group\n",
+			i, MT753X_RESERVED_VLAN);
+	}
+
+	return 0;
+}
+
+static int
 mt7531_setup(struct dsa_switch *ds)
 {
 	struct mt7530_priv *priv = ds->priv;
 	struct mt7530_dummy_poll p;
+	u32 unused_pm = 0;
 	u32 val, id;
 	int ret, i;
 
@@ -1767,7 +1818,9 @@ mt7531_setup(struct dsa_switch *ds)
 
 		mt7530_set(priv, MT7531_DBG_CNT(i), MT7531_DIS_CLR);
 
-		if (dsa_is_cpu_port(ds, i))
+		if (dsa_is_unused_port(ds, i))
+			unused_pm |= BIT(i);
+		else if (dsa_is_cpu_port(ds, i))
 			mt753x_cpu_port_enable(ds, i);
 		else
 			mt7530_port_disable(ds, i);
@@ -1777,6 +1830,9 @@ mt7531_setup(struct dsa_switch *ds)
 			   PVC_EG_TAG(MT7530_VLAN_EG_CONSISTENT));
 	}
 
+	/* Group and enable unused ports as a standalone dumb switch. */
+	setup_unused_ports(ds, unused_pm);
+
 	ds->configure_vlan_while_not_filtering = true;
 
 	/* Flush the FDB table */
@@ -2101,7 +2157,7 @@ mt7531_mac_config(struct dsa_switch *ds,
 	case PHY_INTERFACE_MODE_RGMII_RXID:
 	case PHY_INTERFACE_MODE_RGMII_TXID:
 		dp = dsa_to_port(ds, port);
-		phydev = dp->slave->phydev;
+		phydev = (dp->slave) ? dp->slave->phydev : NULL;
 		return mt7531_rgmii_setup(priv, port, interface, phydev);
 	case PHY_INTERFACE_MODE_SGMII:
 		return mt7531_sgmii_setup_mode_an(priv, port, interface);
@@ -2641,7 +2697,7 @@ mt7530_probe(struct mdio_device *mdiodev
 	if (!priv)
 		return -ENOMEM;
 
-	priv->ds = dsa_switch_alloc(&mdiodev->dev, DSA_MAX_PORTS);
+	priv->ds = dsa_switch_alloc(&mdiodev->dev, MT7530_NUM_PORTS);
 	if (!priv->ds)
 		return -ENOMEM;
 
Index: linux-5.4.124/drivers/net/dsa/mt7530.h
===================================================================
--- linux-5.4.124.orig/drivers/net/dsa/mt7530.h
+++ linux-5.4.124/drivers/net/dsa/mt7530.h
@@ -10,6 +10,7 @@
 #define MT7530_CPU_PORT			6
 #define MT7530_NUM_FDB_RECORDS		2048
 #define MT7530_ALL_MEMBERS		0xff
+#define MT753X_RESERVED_VLAN		2
 
 enum mt753x_id {
 	ID_MT7530 = 0,