ixgbe: disable tx engine before disabling tx laser

Disabling the tx laser while receiving DMA requests
can hang the device.  After this occurs the device
is in a bad state. The GPIO bit never clears when
PCI master access is disabled and a reboot is required
to get the device in a good state again.
Signed-off-by: John Fastabend <john.r.fastabend@intel.com>
Acked-by: Peter P Waskiewicz Jr <peter.p.waskiewicz.jr@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ixgbe/ixgbe_main.c

@@ -3684,10 +3684,6 @@ void ixgbe_down(struct ixgbe_adapter *adapter)
 	/* signal that we are down to the interrupt handler */
 	set_bit(__IXGBE_DOWN, &adapter->state);
 
-	/* power down the optics */
-	if (hw->phy.multispeed_fiber)
-		hw->mac.ops.disable_tx_laser(hw);
-
 	/* disable receive for all VFs and wait one second */
 	if (adapter->num_vfs) {
 		/* ping all the active vfs to let them know we are going down */
@@ -3742,6 +3738,10 @@ void ixgbe_down(struct ixgbe_adapter *adapter)
 		                (IXGBE_READ_REG(hw, IXGBE_DMATXCTL) &
 		                 ~IXGBE_DMATXCTL_TE));
 
+	/* power down the optics */
+	if (hw->phy.multispeed_fiber)
+		hw->mac.ops.disable_tx_laser(hw);
+
 	/* clear n-tuple filters that are cached */
 	ethtool_ntuple_flush(netdev);