net: hns: adds limitation for debug port mtu

If mtu for debug port is set more than 1500, it may cause that packets
are dropped by ppe. So maximum value for debug port should be 1500.
Signed-off-by: Kejian Yan <yankejian@huawei.com>
Signed-off-by: Yisen Zhuang <Yisen.Zhuang@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/hisilicon/hns/hns_dsaf_mac.c

@@ -470,6 +470,9 @@ int hns_mac_set_mtu(struct hns_mac_cb *mac_cb, u32 new_mtu)
 	u32 max_frm = AE_IS_VER1(mac_cb->dsaf_dev->dsaf_ver) ?
 			MAC_MAX_MTU : MAC_MAX_MTU_V2;
 
+	if (mac_cb->mac_type == HNAE_PORT_DEBUG)
+		max_frm = MAC_MAX_MTU_DBG;
+
 	if ((new_mtu < MAC_MIN_MTU) || (new_frm > max_frm) ||
 	    (new_frm > HNS_RCB_RING_MAX_BD_PER_PKT * buf_size))
 		return -EINVAL;

drivers/net/ethernet/hisilicon/hns/hns_dsaf_mac.h

@@ -28,6 +28,7 @@ struct dsaf_device;
 #define MAC_MAX_MTU		9600
 #define MAC_MAX_MTU_V2		9728
 #define MAC_MIN_MTU		68
+#define MAC_MAX_MTU_DBG		MAC_DEFAULT_MTU
 
 #define MAC_DEFAULT_PAUSE_TIME 0xff