e1000e: fix legacy interrupt handling in i219

This fix handles a hardware issue that prevented i219 from
working in legacy interrupts mode (IntMode=0)

Signed-off-by: Yanir Lubetkin <yanirx.lubetkin@intel.com>
Tested-by: Aaron Brown <aaron.f.brown@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 4f029b6..5f94fdf 100644
--- a/drivers/net/ethernet/intel/e1000e/netdev.c
+++ b/drivers/net/ethernet/intel/e1000e/netdev.c
@@ -4120,6 +4120,20 @@
 		phy_data &= ~IGP02E1000_PM_SPD;
 		e1e_wphy(hw, IGP02E1000_PHY_POWER_MGMT, phy_data);
 	}
+	if (hw->mac.type == e1000_pch_spt && adapter->int_mode == 0) {
+		u32 reg;
+
+		/* Fextnvm7 @ 0xe4[2] = 1 */
+		reg = er32(FEXTNVM7);
+		reg |= E1000_FEXTNVM7_SIDE_CLK_UNGATE;
+		ew32(FEXTNVM7, reg);
+		/* Fextnvm9 @ 0x5bb4[13:12] = 11 */
+		reg = er32(FEXTNVM9);
+		reg |= E1000_FEXTNVM9_IOSFSB_CLKGATE_DIS |
+		       E1000_FEXTNVM9_IOSFSB_CLKREQ_DIS;
+		ew32(FEXTNVM9, reg);
+	}
+
 }
 
 int e1000e_up(struct e1000_adapter *adapter)