igb: only support SRRCTL_DROP_EN when using multiple queues

The SRRCTL.DROP_EN bit should only be set when we are supporting
multiple queues. This bit is meant to prevent head of line blocking
and is unnecessary in the single queue case.

Signed-off-by: Nicholas Nunley <nicholasx.d.nunley@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 3 insertions, 0 deletions

diff --git a/drivers/net/igb/igb_main.c b/drivers/net/igb/igb_main.c
index 4ccc7fc70f53..b989b34a4adb 100644
--- a/drivers/net/igb/igb_main.c
+++ b/drivers/net/igb/igb_main.c
@@ -2595,6 +2595,9 @@ void igb_configure_rx_ring(struct igb_adapter *adapter,
                          E1000_SRRCTL_BSIZEPKT_SHIFT;
                 srrctl |= E1000_SRRCTL_DESCTYPE_ADV_ONEBUF;
         }
+        /* Only set Drop Enable if we are supporting multiple queues */
+        if (adapter->vfs_allocated_count || adapter->num_rx_queues > 1)
+                srrctl |= E1000_SRRCTL_DROP_EN;
 
         wr32(E1000_SRRCTL(reg_idx), srrctl);