diff --git a/drivers/net/dsa/microchip/ksz9477.c b/drivers/net/dsa/microchip/ksz9477.c
index b1b86b6..03de50e 100644
--- a/drivers/net/dsa/microchip/ksz9477.c
+++ b/drivers/net/dsa/microchip/ksz9477.c
@@ -450,12 +450,14 @@ static void ksz9477_port_stp_state_set(struct dsa_switch *ds, int port,
 			break;
 
 		member = dev->host_mask | p->vid_member;
+		mutex_lock(&dev->dev_mutex);
 
 		/* Port is a member of a bridge. */
 		if (dev->br_member & (1 << port)) {
 			dev->member |= (1 << port);
 			member = dev->member;
 		}
+		mutex_unlock(&dev->dev_mutex);
 		break;
 	case BR_STATE_BLOCKING:
 		data |= PORT_LEARN_DISABLE;
@@ -470,6 +472,7 @@ static void ksz9477_port_stp_state_set(struct dsa_switch *ds, int port,
 
 	ksz_pwrite8(dev, port, P_STP_CTRL, data);
 	p->stp_state = state;
+	mutex_lock(&dev->dev_mutex);
 	if (data & PORT_RX_ENABLE)
 		dev->rx_ports |= (1 << port);
 	else
@@ -494,6 +497,7 @@ static void ksz9477_port_stp_state_set(struct dsa_switch *ds, int port,
 	 */
 	if (forward != dev->member)
 		ksz_update_port_member(dev, port);
+	mutex_unlock(&dev->dev_mutex);
 }
 
 static void ksz9477_flush_dyn_mac_table(struct ksz_device *dev, int port)
@@ -1080,6 +1084,7 @@ static void ksz9477_port_setup(struct ksz_device *dev, int port, bool cpu_port)
 		ksz_pwrite8(dev, port, REG_PORT_XMII_CTRL_1, data8);
 		p->phydev.duplex = 1;
 	}
+	mutex_lock(&dev->dev_mutex);
 	if (cpu_port) {
 		member = dev->port_mask;
 		dev->on_ports = dev->host_mask;
@@ -1092,6 +1097,7 @@ static void ksz9477_port_setup(struct ksz_device *dev, int port, bool cpu_port)
 		if (p->phydev.link)
 			dev->live_ports |= (1 << port);
 	}
+	mutex_unlock(&dev->dev_mutex);
 	ksz9477_cfg_port_member(dev, port, member);
 
 	/* clear pending interrupts */
diff --git a/drivers/net/dsa/microchip/ksz_common.c b/drivers/net/dsa/microchip/ksz_common.c
index 0589fc7..d89c977 100644
--- a/drivers/net/dsa/microchip/ksz_common.c
+++ b/drivers/net/dsa/microchip/ksz_common.c
@@ -20,6 +20,16 @@
 
 #include "ksz_priv.h"
 
+void ksz_port_cleanup(struct ksz_device *dev, int port)
+{
+	/* Common code for port cleanup. */
+	mutex_lock(&dev->dev_mutex);
+	dev->on_ports &= ~(1 << port);
+	dev->live_ports &= ~(1 << port);
+	mutex_unlock(&dev->dev_mutex);
+}
+EXPORT_SYMBOL_GPL(ksz_port_cleanup);
+
 void ksz_update_port_member(struct ksz_device *dev, int port)
 {
 	struct ksz_port *p;
@@ -151,6 +161,13 @@ void ksz_adjust_link(struct dsa_switch *ds, int port,
 		p->read = true;
 		schedule_work(&dev->mib_read);
 	}
+	mutex_lock(&dev->dev_mutex);
+	if (!phydev->link)
+		dev->live_ports &= ~(1 << port);
+	else
+		/* Remember which port is connected and active. */
+		dev->live_ports |= (1 << port) & dev->on_ports;
+	mutex_unlock(&dev->dev_mutex);
 }
 EXPORT_SYMBOL_GPL(ksz_adjust_link);
 
@@ -188,7 +205,9 @@ int ksz_port_bridge_join(struct dsa_switch *ds, int port,
 {
 	struct ksz_device *dev = ds->priv;
 
+	mutex_lock(&dev->dev_mutex);
 	dev->br_member |= (1 << port);
+	mutex_unlock(&dev->dev_mutex);
 
 	/* port_stp_state_set() will be called after to put the port in
 	 * appropriate state so there is no need to do anything.
@@ -203,8 +222,10 @@ void ksz_port_bridge_leave(struct dsa_switch *ds, int port,
 {
 	struct ksz_device *dev = ds->priv;
 
+	mutex_lock(&dev->dev_mutex);
 	dev->br_member &= ~(1 << port);
 	dev->member &= ~(1 << port);
+	mutex_unlock(&dev->dev_mutex);
 
 	/* port_stp_state_set() will be called after to put the port in
 	 * forwarding state so there is no need to do anything.
@@ -417,6 +438,7 @@ int ksz_switch_register(struct ksz_device *dev,
 		gpiod_set_value(dev->reset_gpio, 0);
 	}
 
+	mutex_init(&dev->dev_mutex);
 	mutex_init(&dev->reg_mutex);
 	mutex_init(&dev->stats_mutex);
 	mutex_init(&dev->alu_mutex);
diff --git a/drivers/net/dsa/microchip/ksz_common.h b/drivers/net/dsa/microchip/ksz_common.h
index eb29bb0..0d25bc4 100644
--- a/drivers/net/dsa/microchip/ksz_common.h
+++ b/drivers/net/dsa/microchip/ksz_common.h
@@ -7,6 +7,7 @@
 #ifndef __KSZ_COMMON_H
 #define __KSZ_COMMON_H
 
+void ksz_port_cleanup(struct ksz_device *dev, int port);
 void ksz_update_port_member(struct ksz_device *dev, int port);
 void ksz_init_mib_timer(struct ksz_device *dev);
 
diff --git a/drivers/net/dsa/microchip/ksz_priv.h b/drivers/net/dsa/microchip/ksz_priv.h
index 1d2d98f..b52e5ca 100644
--- a/drivers/net/dsa/microchip/ksz_priv.h
+++ b/drivers/net/dsa/microchip/ksz_priv.h
@@ -48,6 +48,7 @@ struct ksz_device {
 	struct ksz_platform_data *pdata;
 	const char *name;
 
+	struct mutex dev_mutex;		/* device access */
 	struct mutex reg_mutex;		/* register access */
 	struct mutex stats_mutex;	/* status access */
 	struct mutex alu_mutex;		/* ALU access */
@@ -137,6 +138,7 @@ struct ksz_dev_ops {
 	void (*flush_dyn_mac_table)(struct ksz_device *dev, int port);
 	void (*phy_setup)(struct ksz_device *dev, int port,
 			  struct phy_device *phy);
+	void (*port_cleanup)(struct ksz_device *dev, int port);
 	void (*port_setup)(struct ksz_device *dev, int port, bool cpu_port);
 	void (*r_phy)(struct ksz_device *dev, u16 phy, u16 reg, u16 *val);
 	void (*w_phy)(struct ksz_device *dev, u16 phy, u16 reg, u16 val);
