e1000e: Add code to check for failure of pci_disable_link_state call

This patch attempts to work around a problem found with some systems where
the call to pci_diable_link_state_locked() fails.  As a result, ASPM is not,
in fact, disabled.  Changing disable ASPM code to check if state actually
is disabled after the call and, if not, try another way to disable it.

Signed-off-by: Carolyn Wyborny <carolyn.wyborny@intel.com>
Acked-by: Bruce W. Allan <bruce.w.allan@intel.com>
Tested-by: Pavel Machek <pavel@ucw.cz>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ethernet/intel/e1000e/netdev.c

@@ -64,8 +64,6 @@ static int debug = -1;
 module_param(debug, int, 0);
 MODULE_PARM_DESC(debug, "Debug level (0=none,...,16=all)");
 
-static void e1000e_disable_aspm(struct pci_dev *pdev, u16 state);
-
 static const struct e1000_info *e1000_info_tbl[] = {
 	[board_82571]		= &e1000_82571_info,
 	[board_82572]		= &e1000_82572_info,
@@ -6019,38 +6017,73 @@ static int __e1000_shutdown(struct pci_dev *pdev, bool runtime)
 	return 0;
 }
 
-#ifdef CONFIG_PCIEASPM
-static void __e1000e_disable_aspm(struct pci_dev *pdev, u16 state)
+/**
+ * e1000e_disable_aspm - Disable ASPM states
+ * @pdev: pointer to PCI device struct
+ * @state: bit-mask of ASPM states to disable
+ *
+ * Some devices *must* have certain ASPM states disabled per hardware errata.
+ **/
+static void e1000e_disable_aspm(struct pci_dev *pdev, u16 state)
 {
-	pci_disable_link_state_locked(pdev, state);
-}
-#else
-static void __e1000e_disable_aspm(struct pci_dev *pdev, u16 state)
-{
-	u16 aspm_ctl = 0;
+	struct pci_dev *parent = pdev->bus->self;
+	u16 aspm_dis_mask = 0;
+	u16 pdev_aspmc, parent_aspmc;
 
-	if (state & PCIE_LINK_STATE_L0S)
-		aspm_ctl |= PCI_EXP_LNKCTL_ASPM_L0S;
-	if (state & PCIE_LINK_STATE_L1)
-		aspm_ctl |= PCI_EXP_LNKCTL_ASPM_L1;
+	switch (state) {
+	case PCIE_LINK_STATE_L0S:
+	case PCIE_LINK_STATE_L0S | PCIE_LINK_STATE_L1:
+		aspm_dis_mask |= PCI_EXP_LNKCTL_ASPM_L0S;
+		/* fall-through - can't have L1 without L0s */
+	case PCIE_LINK_STATE_L1:
+		aspm_dis_mask |= PCI_EXP_LNKCTL_ASPM_L1;
+		break;
+	default:
+		return;
+	}
+
+	pcie_capability_read_word(pdev, PCI_EXP_LNKCTL, &pdev_aspmc);
+	pdev_aspmc &= PCI_EXP_LNKCTL_ASPMC;
+
+	if (parent) {
+		pcie_capability_read_word(parent, PCI_EXP_LNKCTL,
+					  &parent_aspmc);
+		parent_aspmc &= PCI_EXP_LNKCTL_ASPMC;
+	}
+
+	/* Nothing to do if the ASPM states to be disabled already are */
+	if (!(pdev_aspmc & aspm_dis_mask) &&
+	    (!parent || !(parent_aspmc & aspm_dis_mask)))
+		return;
+
+	dev_info(&pdev->dev, "Disabling ASPM %s %s\n",
+		 (aspm_dis_mask & pdev_aspmc & PCI_EXP_LNKCTL_ASPM_L0S) ?
+		 "L0s" : "",
+		 (aspm_dis_mask & pdev_aspmc & PCI_EXP_LNKCTL_ASPM_L1) ?
+		 "L1" : "");
+
+#ifdef CONFIG_PCIEASPM
+	pci_disable_link_state_locked(pdev, state);
+
+	/* Double-check ASPM control.  If not disabled by the above, the
+	 * BIOS is preventing that from happening (or CONFIG_PCIEASPM is
+	 * not enabled); override by writing PCI config space directly.
+	 */
+	pcie_capability_read_word(pdev, PCI_EXP_LNKCTL, &pdev_aspmc);
+	pdev_aspmc &= PCI_EXP_LNKCTL_ASPMC;
+
+	if (!(aspm_dis_mask & pdev_aspmc))
+		return;
+#endif
 
 	/* Both device and parent should have the same ASPM setting.
 	 * Disable ASPM in downstream component first and then upstream.
 	 */
-	pcie_capability_clear_word(pdev, PCI_EXP_LNKCTL, aspm_ctl);
+	pcie_capability_clear_word(pdev, PCI_EXP_LNKCTL, aspm_dis_mask);
 
-	if (pdev->bus->self)
-		pcie_capability_clear_word(pdev->bus->self, PCI_EXP_LNKCTL,
-					   aspm_ctl);
-}
-#endif
-static void e1000e_disable_aspm(struct pci_dev *pdev, u16 state)
-{
-	dev_info(&pdev->dev, "Disabling ASPM %s %s\n",
-		 (state & PCIE_LINK_STATE_L0S) ? "L0s" : "",
-		 (state & PCIE_LINK_STATE_L1) ? "L1" : "");
-
-	__e1000e_disable_aspm(pdev, state);
+	if (parent)
+		pcie_capability_clear_word(parent, PCI_EXP_LNKCTL,
+					   aspm_dis_mask);
 }
 
 #ifdef CONFIG_PM