e1000e: Export S0ix flags to ethtool

This flag can be used by an end user to disable S0ix flows on a
buggy system or by an OEM for development purposes.

If you need this flag to be persisted across reboots, it's suggested
to use a udev rule to call adjust it until the kernel could have your
configuration in a disallow list.

Signed-off-by: Mario Limonciello <mario.limonciello@dell.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Tested-by: Yijun Shen <Yijun.shen@dell.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
diff --git a/drivers/net/ethernet/intel/e1000e/netdev.c b/drivers/net/ethernet/intel/e1000e/netdev.c
index b9800ba..e9b82c2 100644
--- a/drivers/net/ethernet/intel/e1000e/netdev.c
+++ b/drivers/net/ethernet/intel/e1000e/netdev.c
@@ -6923,7 +6923,6 @@ static __maybe_unused int e1000e_pm_suspend(struct device *dev)
 	struct net_device *netdev = pci_get_drvdata(to_pci_dev(dev));
 	struct e1000_adapter *adapter = netdev_priv(netdev);
 	struct pci_dev *pdev = to_pci_dev(dev);
-	struct e1000_hw *hw = &adapter->hw;
 	int rc;
 
 	e1000e_flush_lpic(pdev);
@@ -6935,7 +6934,7 @@ static __maybe_unused int e1000e_pm_suspend(struct device *dev)
 		e1000e_pm_thaw(dev);
 	} else {
 		/* Introduce S0ix implementation */
-		if (hw->mac.type >= e1000_pch_cnp)
+		if (adapter->flags2 & FLAG2_ENABLE_S0IX_FLOWS)
 			e1000e_s0ix_entry_flow(adapter);
 	}
 
@@ -6947,11 +6946,10 @@ static __maybe_unused int e1000e_pm_resume(struct device *dev)
 	struct net_device *netdev = pci_get_drvdata(to_pci_dev(dev));
 	struct e1000_adapter *adapter = netdev_priv(netdev);
 	struct pci_dev *pdev = to_pci_dev(dev);
-	struct e1000_hw *hw = &adapter->hw;
 	int rc;
 
 	/* Introduce S0ix implementation */
-	if (hw->mac.type >= e1000_pch_cnp)
+	if (adapter->flags2 & FLAG2_ENABLE_S0IX_FLOWS)
 		e1000e_s0ix_exit_flow(adapter);
 
 	rc = __e1000_resume(pdev);
@@ -7615,6 +7613,9 @@ static int e1000_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 	if (!(adapter->flags & FLAG_HAS_AMT))
 		e1000e_get_hw_control(adapter);
 
+	if (hw->mac.type >= e1000_pch_cnp)
+		adapter->flags2 |= FLAG2_ENABLE_S0IX_FLOWS;
+
 	strlcpy(netdev->name, "eth%d", sizeof(netdev->name));
 	err = register_netdev(netdev);
 	if (err)