ixgbe: make sure per Rx queue is disabled before unmapping the receive buffer

When disable the Rx logic globally, we would also want to disable the per Rx
queue receive logic by per queue Rx control register RXDCTL so no more DMA is
happening from the packet buffer to the receive buffer associated with the Rx
ring, before we start unmapping Rx ring receive buffer. The hardware may take
max of 100us before the corresponding Rx queue is really disabled. Added
ixgbe_disable_rx_queue() for this purpose.

Signed-off-by: Yi Zou <yi.zou@intel.com>
Tested-by: Stephen Ko <stephen.s.ko@intel.com>
Tested-by: Ross Brattain <ross.b.brattain@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/ixgbe/ixgbe.h b/drivers/net/ixgbe/ixgbe.h
index 3ae30b8..bdeaa9e 100644
--- a/drivers/net/ixgbe/ixgbe.h
+++ b/drivers/net/ixgbe/ixgbe.h
@@ -508,6 +508,8 @@
 extern void ixgbe_free_tx_resources(struct ixgbe_ring *);
 extern void ixgbe_configure_rx_ring(struct ixgbe_adapter *,struct ixgbe_ring *);
 extern void ixgbe_configure_tx_ring(struct ixgbe_adapter *,struct ixgbe_ring *);
+extern void ixgbe_disable_rx_queue(struct ixgbe_adapter *adapter,
+				   struct ixgbe_ring *);
 extern void ixgbe_update_stats(struct ixgbe_adapter *adapter);
 extern int ixgbe_init_interrupt_scheme(struct ixgbe_adapter *adapter);
 extern void ixgbe_clear_interrupt_scheme(struct ixgbe_adapter *adapter);