net/mlx4_en: Fix HW timestamp init issue upon system startup

mlx4_en_init_timestamp was called before creation of netdev and port
init, thus used uninitialized values.  Specifically - NIC frequency was
incorrect causing wrong calculations and later wrong HW timestamps.

Fixes: 1ec4864b1017 ('net/mlx4_en: Fixed crash when port type is changed')
Signed-off-by: Eugenia Emantayev <eugenia@mellanox.com>
Signed-off-by: Marina Varshaver <marinav@mellanox.com>
Signed-off-by: Eran Ben Elisha <eranbe@mellanox.com>
Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/ethernet/mellanox/mlx4/en_clock.c b/drivers/net/ethernet/mellanox/mlx4/en_clock.c
index 8a083d7..038f9ce 100644
--- a/drivers/net/ethernet/mellanox/mlx4/en_clock.c
+++ b/drivers/net/ethernet/mellanox/mlx4/en_clock.c
@@ -242,6 +242,13 @@
 	unsigned long flags;
 	u64 ns, zero = 0;
 
+	/* mlx4_en_init_timestamp is called for each netdev.
+	 * mdev->ptp_clock is common for all ports, skip initialization if
+	 * was done for other port.
+	 */
+	if (mdev->ptp_clock)
+		return;
+
 	rwlock_init(&mdev->clock_lock);
 
 	memset(&mdev->cycles, 0, sizeof(mdev->cycles));