e1000e: disable jumbo frames on 82579 when MACsec enabled in EEPROM

If/when an OEM enables MACsec in the 82579 EEPROM, disable jumbo frames
support in the driver due to an interoperability issue in hardware that
prevents jumbo packets from being transmitted or received.

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>

1 files changed, 7 insertions, 1 deletions

diff --git a/drivers/net/e1000e/ich8lan.c b/drivers/net/e1000e/ich8lan.c
index 9b434c0cbc9..ce1dbfdca11 100644
--- a/drivers/net/e1000e/ich8lan.c
+++ b/drivers/net/e1000e/ich8lan.c
@@ -758,7 +758,13 @@ static s32 e1000_get_variants_ich8lan(struct e1000_adapter *adapter)
         if (rc)
                 return rc;
 
-        if (adapter->hw.phy.type == e1000_phy_ife) {
+        /*
+         * Disable Jumbo Frame support on parts with Intel 10/100 PHY or
+         * on parts with MACsec enabled in NVM (reflected in CTRL_EXT).
+         */
+        if ((adapter->hw.phy.type == e1000_phy_ife) ||
+            ((adapter->hw.mac.type >= e1000_pch2lan) &&
+             (!(er32(CTRL_EXT) & E1000_CTRL_EXT_LSECCK)))) {
                 adapter->flags &= ~FLAG_HAS_JUMBO_FRAMES;
                 adapter->max_hw_frame_size = ETH_FRAME_LEN + ETH_FCS_LEN;
         }