e1000e: partial revert of 3ec2a2b8 plus FC workraround for 82577/8

Commit 3ec2a2b80f3eb53851fe4cef9e65b5d33376ef89 broke Tx/Rx when using
jumbo frames on certain parts (i.e. only PAUSE frames could be exchanged
once the high water mark was reached preventing normal packet traffic).
This patch reverts the breakage and sets appropriate high and low water
marks of the Rx FIFO for 82577/82578 which require a workaround due to a
flow control issue in hardware.

Signed-off-by: Bruce Allan <bruce.w.allan@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 29 insertions, 12 deletions

diff --git a/drivers/net/e1000e/netdev.c b/drivers/net/e1000e/netdev.c
index 0687c6aa4e46..a1a5a6f15a65 100644
--- a/drivers/net/e1000e/netdev.c
+++ b/drivers/net/e1000e/netdev.c
@@ -2769,25 +2769,38 @@ void e1000e_reset(struct e1000_adapter *adapter)
         /*
          * flow control settings
          *
-         * The high water mark must be low enough to fit two full frame
+         * The high water mark must be low enough to fit one full frame
          * (or the size used for early receive) above it in the Rx FIFO.
          * Set it to the lower of:
          * - 90% of the Rx FIFO size, and
          * - the full Rx FIFO size minus the early receive size (for parts
          *   with ERT support assuming ERT set to E1000_ERT_2048), or
-         * - the full Rx FIFO size minus two full frames
+         * - the full Rx FIFO size minus one full frame
          */
-        if ((adapter->flags & FLAG_HAS_ERT) &&
-            (adapter->netdev->mtu > ETH_DATA_LEN))
-                hwm = min(((pba << 10) * 9 / 10),
-                          ((pba << 10) - (E1000_ERT_2048 << 3)));
-        else
-                hwm = min(((pba << 10) * 9 / 10),
-                          ((pba << 10) - (2 * adapter->max_frame_size)));
+        if (hw->mac.type == e1000_pchlan) {
+                /*
+                 * Workaround PCH LOM adapter hangs with certain network
+                 * loads.  If hangs persist, try disabling Tx flow control.
+                 */
+                if (adapter->netdev->mtu > ETH_DATA_LEN) {
+                        fc->high_water = 0x3500;
+                        fc->low_water  = 0x1500;
+                } else {
+                        fc->high_water = 0x5000;
+                        fc->low_water  = 0x3000;
+                }
+        } else {
+                if ((adapter->flags & FLAG_HAS_ERT) &&
+                    (adapter->netdev->mtu > ETH_DATA_LEN))
+                        hwm = min(((pba << 10) * 9 / 10),
+                                  ((pba << 10) - (E1000_ERT_2048 << 3)));
+                else
+                        hwm = min(((pba << 10) * 9 / 10),
+                                  ((pba << 10) - adapter->max_frame_size));
 
-        fc->high_water = hwm & E1000_FCRTH_RTH; /* 8-byte granularity */
-        fc->low_water = (fc->high_water - (2 * adapter->max_frame_size));
-        fc->low_water &= E1000_FCRTL_RTL; /* 8-byte granularity */
+                fc->high_water = hwm & E1000_FCRTH_RTH; /* 8-byte granularity */
+                fc->low_water = fc->high_water - 8;
+        }
 
         if (adapter->flags & FLAG_DISABLE_FC_PAUSE_TIME)
                 fc->pause_time = 0xFFFF;
@@ -2813,6 +2826,10 @@ void e1000e_reset(struct e1000_adapter *adapter)
         if (mac->ops.init_hw(hw))
                 e_err("Hardware Error\n");
 
+        /* additional part of the flow-control workaround above */
+        if (hw->mac.type == e1000_pchlan)
+                ew32(FCRTV_PCH, 0x1000);
+
         e1000_update_mng_vlan(adapter);
 
         /* Enable h/w to recognize an 802.1Q VLAN Ethernet packet */