igb: update handling of RCTL for smaller buffer sizes

As we begin to move into virtualization the use of a global value for
buffer sizes becomes undesirable.  This change makes it so only 256 and 512
byte buffers require use of the RCTL register.

Signed-off-by: Alexander Duyck <alexander.h.duyck@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/igb/igb_main.c b/drivers/net/igb/igb_main.c
index c49b8d8..dad742f 100644 (file)
--- a/drivers/net/igb/igb_main.c
+++ b/drivers/net/igb/igb_main.c
@@ -1801,25 +1801,21 @@ static void igb_setup_rctl(struct igb_adapter *adapter)
         */
        rctl &= ~(E1000_RCTL_SBP | E1000_RCTL_LPE | E1000_RCTL_SZ_256);
 
-       if (adapter->netdev->mtu <= ETH_DATA_LEN) {
-               /* Setup buffer sizes */
-               switch (adapter->rx_buffer_len) {
-               case IGB_RXBUFFER_256:
-                       rctl |= E1000_RCTL_SZ_256;
-                       break;
-               case IGB_RXBUFFER_512:
-                       rctl |= E1000_RCTL_SZ_512;
-                       break;
-               case IGB_RXBUFFER_1024:
-                       rctl |= E1000_RCTL_SZ_1024;
-                       break;
-               default:
-                       rctl |= E1000_RCTL_SZ_2048;
-                       break;
-               }
-       } else {
+       if (adapter->netdev->mtu > ETH_DATA_LEN)
                rctl |= E1000_RCTL_LPE;
-               srrctl = adapter->rx_buffer_len >> E1000_SRRCTL_BSIZEPKT_SHIFT;
+
+       /* Setup buffer sizes */
+       switch (adapter->rx_buffer_len) {
+       case IGB_RXBUFFER_256:
+               rctl |= E1000_RCTL_SZ_256;
+               break;
+       case IGB_RXBUFFER_512:
+               rctl |= E1000_RCTL_SZ_512;
+               break;
+       default:
+               srrctl = ALIGN(adapter->rx_buffer_len, 1024)
+                        >> E1000_SRRCTL_BSIZEPKT_SHIFT;
+               break;
        }
 
        /* 82575 and greater support packet-split where the protocol