diff --git a/drivers/net/fm/p1023.c b/drivers/net/fm/p1023.c
index b17dc40b8a..9765da5b23 100644
--- a/drivers/net/fm/p1023.c
+++ b/drivers/net/fm/p1023.c
@@ -39,6 +39,11 @@ static int is_device_disabled(enum fm_port port)
 void fman_disable_port(enum fm_port port)
 {
 	ccsr_gur_t *gur = (void *)(CONFIG_SYS_MPC85xx_GUTS_ADDR);
+
+	/* don't allow disabling of DTSEC1 as its needed for MDIO */
+	if (port == FM1_DTSEC1)
+		return;
+
 	setbits_be32(&gur->devdisr, port_to_devdisr[port]);
 }
 
diff --git a/drivers/net/fm/p3060.c b/drivers/net/fm/p3060.c
index 176e1d292c..c9748a954c 100644
--- a/drivers/net/fm/p3060.c
+++ b/drivers/net/fm/p3060.c
@@ -45,6 +45,11 @@ static int is_device_disabled(enum fm_port port)
 void fman_disable_port(enum fm_port port)
 {
 	ccsr_gur_t *gur = (void *)(CONFIG_SYS_MPC85xx_GUTS_ADDR);
+
+	/* don't allow disabling of DTSEC1 as its needed for MDIO */
+	if (port == FM1_DTSEC1)
+		return;
+
 	setbits_be32(&gur->devdisr2, port_to_devdisr[port]);
 }
 
diff --git a/drivers/net/fm/p4080.c b/drivers/net/fm/p4080.c
index 791caab7ec..9dc6049c36 100644
--- a/drivers/net/fm/p4080.c
+++ b/drivers/net/fm/p4080.c
@@ -47,6 +47,11 @@ static int is_device_disabled(enum fm_port port)
 void fman_disable_port(enum fm_port port)
 {
 	ccsr_gur_t *gur = (void *)(CONFIG_SYS_MPC85xx_GUTS_ADDR);
+
+	/* don't allow disabling of DTSEC1 as its needed for MDIO */
+	if (port == FM1_DTSEC1)
+		return;
+
 	setbits_be32(&gur->devdisr2, port_to_devdisr[port]);
 }
 
diff --git a/drivers/net/fm/p5020.c b/drivers/net/fm/p5020.c
index 69c27d2237..a7a6e43fe2 100644
--- a/drivers/net/fm/p5020.c
+++ b/drivers/net/fm/p5020.c
@@ -43,6 +43,11 @@ static int is_device_disabled(enum fm_port port)
 void fman_disable_port(enum fm_port port)
 {
 	ccsr_gur_t *gur = (void *)(CONFIG_SYS_MPC85xx_GUTS_ADDR);
+
+	/* don't allow disabling of DTSEC1 as its needed for MDIO */
+	if (port == FM1_DTSEC1)
+		return;
+
 	setbits_be32(&gur->devdisr2, port_to_devdisr[port]);
 }