3 files changed, 44 insertions, 22 deletions

diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
index 2672c798272f..7aff6312ce7c 100644
--- a/drivers/acpi/pci_root.c
+++ b/drivers/acpi/pci_root.c
@@ -596,6 +596,13 @@ static int __devinit acpi_pci_root_add(struct acpi_device *device)
                 if (ACPI_SUCCESS(status)) {
                         dev_info(root->bus->bridge,
                                 "ACPI _OSC control (0x%02x) granted\n", flags);
+                        if (acpi_gbl_FADT.boot_flags & ACPI_FADT_NO_ASPM) {
+                                /*
+                                 * We have ASPM control, but the FADT indicates
+                                 * that it's unsupported. Clear it.
+                                 */
+                                pcie_clear_aspm(root->bus);
+                        }
                 } else {
                         dev_info(root->bus->bridge,
                                 "ACPI _OSC request failed (%s), "
diff --git a/drivers/pci/pci-acpi.c b/drivers/pci/pci-acpi.c
index 4ecb6408b0d6..c8e75851a314 100644
--- a/drivers/pci/pci-acpi.c
+++ b/drivers/pci/pci-acpi.c
@@ -395,7 +395,6 @@ static int __init acpi_pci_init(void)
 
         if (acpi_gbl_FADT.boot_flags & ACPI_FADT_NO_ASPM) {
                 printk(KERN_INFO"ACPI FADT declares the system doesn't support PCIe ASPM, so disable it\n");
-                pcie_clear_aspm();
                 pcie_no_aspm();
         }
 
diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c
index cbfbab18be91..1cfbf228fbb1 100644
--- a/drivers/pci/pcie/aspm.c
+++ b/drivers/pci/pcie/aspm.c
@@ -68,7 +68,7 @@ struct pcie_link_state {
         struct aspm_latency acceptable[8];
 };
 
-static int aspm_disabled, aspm_force, aspm_clear_state;
+static int aspm_disabled, aspm_force;
 static bool aspm_support_enabled = true;
 static DEFINE_MUTEX(aspm_lock);
 static LIST_HEAD(link_list);
@@ -500,9 +500,6 @@ static int pcie_aspm_sanity_check(struct pci_dev *pdev)
         int pos;
         u32 reg32;
 
-        if (aspm_clear_state)
-                return -EINVAL;
-
         /*
          * Some functions in a slot might not all be PCIe functions,
          * very strange. Disable ASPM for the whole slot
@@ -574,9 +571,6 @@ void pcie_aspm_init_link_state(struct pci_dev *pdev)
             pdev->pcie_type != PCI_EXP_TYPE_DOWNSTREAM)
                 return;
 
-        if (aspm_disabled && !aspm_clear_state)
-                return;
-
         /* VIA has a strange chipset, root port is under a bridge */
         if (pdev->pcie_type == PCI_EXP_TYPE_ROOT_PORT &&
             pdev->bus->self)
@@ -608,7 +602,7 @@ void pcie_aspm_init_link_state(struct pci_dev *pdev)
          * the BIOS's expectation, we'll do so once pci_enable_device() is
          * called.
          */
-        if (aspm_policy != POLICY_POWERSAVE || aspm_clear_state) {
+        if (aspm_policy != POLICY_POWERSAVE) {
                 pcie_config_aspm_path(link);
                 pcie_set_clkpm(link, policy_to_clkpm_state(link));
         }
@@ -649,8 +643,7 @@ void pcie_aspm_exit_link_state(struct pci_dev *pdev)
         struct pci_dev *parent = pdev->bus->self;
         struct pcie_link_state *link, *root, *parent_link;
 
-        if ((aspm_disabled && !aspm_clear_state) || !pci_is_pcie(pdev) ||
-            !parent || !parent->link_state)
+        if (!pci_is_pcie(pdev) || !parent || !parent->link_state)
                 return;
         if ((parent->pcie_type != PCI_EXP_TYPE_ROOT_PORT) &&
             (parent->pcie_type != PCI_EXP_TYPE_DOWNSTREAM))
@@ -734,13 +727,18 @@ void pcie_aspm_powersave_config_link(struct pci_dev *pdev)
  * pci_disable_link_state - disable pci device's link state, so the link will
  * never enter specific states
  */
-static void __pci_disable_link_state(struct pci_dev *pdev, int state, bool sem)
+static void __pci_disable_link_state(struct pci_dev *pdev, int state, bool sem,
+                                     bool force)
 {
         struct pci_dev *parent = pdev->bus->self;
         struct pcie_link_state *link;
 
-        if (aspm_disabled || !pci_is_pcie(pdev))
+        if (aspm_disabled && !force)
+                return;
+
+        if (!pci_is_pcie(pdev))
                 return;
+
         if (pdev->pcie_type == PCI_EXP_TYPE_ROOT_PORT ||
             pdev->pcie_type == PCI_EXP_TYPE_DOWNSTREAM)
                 parent = pdev;
@@ -768,16 +766,31 @@ static void __pci_disable_link_state(struct pci_dev *pdev, int state, bool sem)
 
 void pci_disable_link_state_locked(struct pci_dev *pdev, int state)
 {
-        __pci_disable_link_state(pdev, state, false);
+        __pci_disable_link_state(pdev, state, false, false);
 }
 EXPORT_SYMBOL(pci_disable_link_state_locked);
 
 void pci_disable_link_state(struct pci_dev *pdev, int state)
 {
-        __pci_disable_link_state(pdev, state, true);
+        __pci_disable_link_state(pdev, state, true, false);
 }
 EXPORT_SYMBOL(pci_disable_link_state);
 
+void pcie_clear_aspm(struct pci_bus *bus)
+{
+        struct pci_dev *child;
+
+        /*
+         * Clear any ASPM setup that the firmware has carried out on this bus
+         */
+        list_for_each_entry(child, &bus->devices, bus_list) {
+                __pci_disable_link_state(child, PCIE_LINK_STATE_L0S |
+                                         PCIE_LINK_STATE_L1 |
+                                         PCIE_LINK_STATE_CLKPM,
+                                         false, true);
+        }
+}
+
 static int pcie_aspm_set_policy(const char *val, struct kernel_param *kp)
 {
         int i;
@@ -935,6 +948,7 @@ void pcie_aspm_remove_sysfs_dev_files(struct pci_dev *pdev)
 static int __init pcie_aspm_disable(char *str)
 {
         if (!strcmp(str, "off")) {
+                aspm_policy = POLICY_DEFAULT;
                 aspm_disabled = 1;
                 aspm_support_enabled = false;
                 printk(KERN_INFO "PCIe ASPM is disabled\n");
@@ -947,16 +961,18 @@ static int __init pcie_aspm_disable(char *str)
 
 __setup("pcie_aspm=", pcie_aspm_disable);
 
-void pcie_clear_aspm(void)
-{
-        if (!aspm_force)
-                aspm_clear_state = 1;
-}
-
 void pcie_no_aspm(void)
 {
-        if (!aspm_force)
+        /*
+         * Disabling ASPM is intended to prevent the kernel from modifying
+         * existing hardware state, not to clear existing state. To that end:
+         * (a) set policy to POLICY_DEFAULT in order to avoid changing state
+         * (b) prevent userspace from changing policy
+         */
+        if (!aspm_force) {
+                aspm_policy = POLICY_DEFAULT;
                 aspm_disabled = 1;
+        }
 }
 
 /**