diff --git a/drivers/net/sfc/net_driver.h b/drivers/net/sfc/net_driver.h
index 5fffd9abffdec901b88b8a733d4d4fd1d08f181d..4762c91cb587f03c19eddd58abef2ea449a2e941 100644
--- a/drivers/net/sfc/net_driver.h
+++ b/drivers/net/sfc/net_driver.h
@@ -645,7 +645,6 @@ union efx_multicast_hash {
  * struct efx_nic - an Efx NIC
  * @name: Device name (net device name or bus id before net device registered)
  * @pci_dev: The PCI device
- * @port_num: Index of this host port within the controller
  * @type: Controller type attributes
  * @legacy_irq: IRQ number
  * @workqueue: Workqueue for port reconfigures and the HW monitor.
@@ -729,7 +728,6 @@ union efx_multicast_hash {
 struct efx_nic {
 	char name[IFNAMSIZ];
 	struct pci_dev *pci_dev;
-	unsigned port_num;
 	const struct efx_nic_type *type;
 	int legacy_irq;
 	struct workqueue_struct *workqueue;
@@ -832,7 +830,7 @@ static inline const char *efx_dev_name(struct efx_nic *efx)
 
 static inline unsigned int efx_port_num(struct efx_nic *efx)
 {
-	return efx->port_num;
+	return efx->net_dev->dev_id;
 }
 
 /**
diff --git a/drivers/net/sfc/siena.c b/drivers/net/sfc/siena.c
index 7ecd255a7cc0075ccfb4c2c0a852e1696e9e6dcf..f2b1e6180753536336921b90f53f62c8675fda72 100644
--- a/drivers/net/sfc/siena.c
+++ b/drivers/net/sfc/siena.c
@@ -222,7 +222,7 @@ static int siena_probe_nic(struct efx_nic *efx)
 	}
 
 	efx_reado(efx, &reg, FR_AZ_CS_DEBUG);
-	efx->port_num = EFX_OWORD_FIELD(reg, FRF_CZ_CS_PORT_NUM) - 1;
+	efx->net_dev->dev_id = EFX_OWORD_FIELD(reg, FRF_CZ_CS_PORT_NUM) - 1;
 
 	efx_mcdi_init(efx);