igb: Fix SGMII SFP module discovery for 100FX/LX.

Changing the link mode should also be done for 100BaseFX SGMII modules,
otherwise they just don't work when the default link mode in CTRL_EXT
coming from the EEPROM is SERDES.

Additionally 100Base-LX SGMII SFP modules are also supported now, which
was not the case before.

Tested with an i210 using Flexoptix S.1303.2M.G 100FX and
S.1303.10.G 100LX SGMII SFP modules.
Signed-off-by: Manfred Rudigier <manfred.rudigier@omicronenergy.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ethernet/intel/igb/e1000_82575.c

@@ -530,7 +530,7 @@ static s32 igb_set_sfp_media_type_82575(struct e1000_hw *hw)
 		dev_spec->module_plugged = true;
 		if (eth_flags->e1000_base_lx || eth_flags->e1000_base_sx) {
 			hw->phy.media_type = e1000_media_type_internal_serdes;
-		} else if (eth_flags->e100_base_fx) {
+		} else if (eth_flags->e100_base_fx || eth_flags->e100_base_lx) {
 			dev_spec->sgmii_active = true;
 			hw->phy.media_type = e1000_media_type_internal_serdes;
 		} else if (eth_flags->e1000_base_t) {
@@ -657,14 +657,10 @@ static s32 igb_get_invariants_82575(struct e1000_hw *hw)
 			break;
 		}
 
-		/* do not change link mode for 100BaseFX */
-		if (dev_spec->eth_flags.e100_base_fx)
-			break;
-
 		/* change current link mode setting */
 		ctrl_ext &= ~E1000_CTRL_EXT_LINK_MODE_MASK;
 
-		if (hw->phy.media_type == e1000_media_type_copper)
+		if (dev_spec->sgmii_active)
 			ctrl_ext |= E1000_CTRL_EXT_LINK_MODE_SGMII;
 		else
 			ctrl_ext |= E1000_CTRL_EXT_LINK_MODE_PCIE_SERDES;

drivers/net/ethernet/intel/igb/igb_ethtool.c

@@ -181,7 +181,7 @@ static int igb_get_link_ksettings(struct net_device *netdev,
 				advertising &= ~ADVERTISED_1000baseKX_Full;
 			}
 		}
-		if (eth_flags->e100_base_fx) {
+		if (eth_flags->e100_base_fx || eth_flags->e100_base_lx) {
 			supported |= SUPPORTED_100baseT_Full;
 			advertising |= ADVERTISED_100baseT_Full;
 		}