e1000e: fix flow-control thresholds for jumbo frames on 82579/I217/I218

The previous static flow-control thresholds were causing unnecessary pause
packets to be transmitted when jumbo frames are configured reducing the
throughput.

Signed-off-by: Bruce Allan <bruce.w.allan@intel.com>
Tested-by: Jeff Pieper <jeffrey.e.pieper@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

diff --git a/drivers/net/ethernet/intel/e1000e/netdev.c b/drivers/net/ethernet/intel/e1000e/netdev.c
index c15b7e4..8bb5d28 100644 (file)
--- a/drivers/net/ethernet/intel/e1000e/netdev.c
+++ b/drivers/net/ethernet/intel/e1000e/netdev.c
@@ -3724,14 +3724,17 @@ void e1000e_reset(struct e1000_adapter *adapter)
                break;
        case e1000_pch2lan:
        case e1000_pch_lpt:
-               fc->high_water = 0x05C20;
-               fc->low_water = 0x05048;
-               fc->pause_time = 0x0650;
                fc->refresh_time = 0x0400;
-               if (adapter->netdev->mtu > ETH_DATA_LEN) {
-                       pba = 14;
-                       ew32(PBA, pba);
+
+               if (adapter->netdev->mtu <= ETH_DATA_LEN) {
+                       fc->high_water = 0x05C20;
+                       fc->low_water = 0x05048;
+                       fc->pause_time = 0x0650;
+                       break;
                }
+
+               fc->high_water = ((pba << 10) * 9 / 10) & E1000_FCRTH_RTH;
+               fc->low_water = ((pba << 10) * 8 / 10) & E1000_FCRTL_RTL;
                break;
        }