octeon_ep: get max rx packet length from firmware

Max receive packet length can vary across SoCs, so
this needs to be queried from respective firmware and
filled by driver. A control net get mtu api should be
implemented to do the same.
Signed-off-by: Shinas Rasheed <srasheed@marvell.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/marvell/octeon_ep/octep_config.h

@@ -45,8 +45,6 @@
 
 /* Minimum MTU supported by Octeon network interface */
 #define OCTEP_MIN_MTU        ETH_MIN_MTU
-/* Maximum MTU supported by Octeon interface*/
-#define OCTEP_MAX_MTU        (10000 - (ETH_HLEN + ETH_FCS_LEN))
 /* Default MTU */
 #define OCTEP_DEFAULT_MTU    1500
 

drivers/net/ethernet/marvell/octeon_ep/octep_ctrl_net.c

@@ -198,6 +198,24 @@ int octep_ctrl_net_set_mac_addr(struct octep_device *oct, int vfid, u8 *addr,
 	return octep_send_mbox_req(oct, &d, wait_for_response);
 }
 
+int octep_ctrl_net_get_mtu(struct octep_device *oct, int vfid)
+{
+	struct octep_ctrl_net_wait_data d = {};
+	struct octep_ctrl_net_h2f_req *req;
+	int err;
+
+	req = &d.data.req;
+	init_send_req(&d.msg, req, mtu_sz, vfid);
+	req->hdr.s.cmd = OCTEP_CTRL_NET_H2F_CMD_MTU;
+	req->mtu.cmd = OCTEP_CTRL_NET_CMD_GET;
+
+	err = octep_send_mbox_req(oct, &d, true);
+	if (err < 0)
+		return err;
+
+	return d.data.resp.mtu.val;
+}
+
 int octep_ctrl_net_set_mtu(struct octep_device *oct, int vfid, int mtu,
 			   bool wait_for_response)
 {

drivers/net/ethernet/marvell/octeon_ep/octep_ctrl_net.h

@@ -287,6 +287,16 @@ int octep_ctrl_net_get_mac_addr(struct octep_device *oct, int vfid, u8 *addr);
 int octep_ctrl_net_set_mac_addr(struct octep_device *oct, int vfid, u8 *addr,
 				bool wait_for_response);
 
+/**
+ * octep_ctrl_net_get_mtu() - Get max MTU from firmware.
+ *
+ * @oct: non-null pointer to struct octep_device.
+ * @vfid: Index of virtual function.
+ *
+ * return value: mtu on success, -errno on failure.
+ */
+int octep_ctrl_net_get_mtu(struct octep_device *oct, int vfid);
+
 /** 
  * octep_ctrl_net_set_mtu() - Set mtu in firmware.
  *

drivers/net/ethernet/marvell/octeon_ep/octep_main.c

@@ -1307,6 +1307,7 @@ static int octep_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 {
 	struct octep_device *octep_dev = NULL;
 	struct net_device *netdev;
+	int max_rx_pktlen;
 	int err;
 
 	err = pci_enable_device(pdev);
@@ -1377,8 +1378,15 @@ static int octep_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 
 	netdev->hw_features = NETIF_F_SG;
 	netdev->features |= netdev->hw_features;
+
+	max_rx_pktlen = octep_ctrl_net_get_mtu(octep_dev, OCTEP_CTRL_NET_INVALID_VFID);
+	if (max_rx_pktlen < 0) {
+		dev_err(&octep_dev->pdev->dev,
+			"Failed to get max receive packet size; err = %d\n", max_rx_pktlen);
+		goto register_dev_err;
+	}
 	netdev->min_mtu = OCTEP_MIN_MTU;
-	netdev->max_mtu = OCTEP_MAX_MTU;
+	netdev->max_mtu = max_rx_pktlen - (ETH_HLEN + ETH_FCS_LEN);
 	netdev->mtu = OCTEP_DEFAULT_MTU;
 
 	err = octep_ctrl_net_get_mac_addr(octep_dev, OCTEP_CTRL_NET_INVALID_VFID,