diff -ur a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c --- a/drivers/acpi/pci_root.c 2012-01-19 19:45:17.000000000 +0100 +++ b/drivers/acpi/pci_root.c 2012-02-12 03:20:19.104634583 +0100 @@ -33,6 +33,7 @@ #include #include #include +#include #include #include #include @@ -583,12 +584,21 @@ status = acpi_pci_osc_control_set(device->handle, &flags, OSC_PCI_EXPRESS_CAP_STRUCTURE_CONTROL); - if (ACPI_SUCCESS(status)) + if (ACPI_SUCCESS(status)) { dev_info(root->bus->bridge, "ACPI _OSC control (0x%02x) granted\n", flags); - else + 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_dbg(root->bus->bridge, "ACPI _OSC request failed (code %d)\n", status); + pcie_no_aspm(); + } } return 0; diff -ur a/drivers/pci/pci-acpi.c b/drivers/pci/pci-acpi.c --- a/drivers/pci/pci-acpi.c 2012-01-19 19:44:15.000000000 +0100 +++ b/drivers/pci/pci-acpi.c 2012-02-12 01:39:31.441635301 +0100 @@ -195,7 +195,6 @@ 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 -ur a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c --- a/drivers/pci/pcie/aspm.c 2012-01-19 19:45:17.000000000 +0100 +++ b/drivers/pci/pcie/aspm.c 2012-02-12 01:39:31.449635162 +0100 @@ -68,7 +68,7 @@ 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 @@ 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 @@ 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 @@ * 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 @@ struct pci_dev *parent = pdev->bus->self; struct pcie_link_state *link, *root, *parent_link; - if ((aspm_disabled && !aspm_clear_state) || !pdev->is_pcie || - !parent || !parent->link_state) + if (!pdev->is_pcie || !parent || !parent->link_state) return; if ((parent->pcie_type != PCI_EXP_TYPE_ROOT_PORT) && (parent->pcie_type != PCI_EXP_TYPE_DOWNSTREAM)) @@ -712,13 +705,18 @@ * 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 || !pdev->is_pcie) + if (aspm_disabled && !force) + return; + + if (!pdev->is_pcie) return; + if (pdev->pcie_type == PCI_EXP_TYPE_ROOT_PORT || pdev->pcie_type == PCI_EXP_TYPE_DOWNSTREAM) parent = pdev; @@ -746,16 +744,31 @@ 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; @@ -907,6 +920,7 @@ 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"); @@ -919,16 +933,18 @@ __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; + } } /** diff -ur a/include/linux/pci-aspm.h b/include/linux/pci-aspm.h --- a/include/linux/pci-aspm.h 2012-01-19 19:44:42.000000000 +0100 +++ b/include/linux/pci-aspm.h 2012-02-12 01:39:31.452664277 +0100 @@ -28,7 +28,7 @@ extern void pcie_aspm_pm_state_change(struct pci_dev *pdev); extern void pci_disable_link_state(struct pci_dev *pdev, int state); extern void pci_disable_link_state_locked(struct pci_dev *pdev, int state); -extern void pcie_clear_aspm(void); +extern void pcie_clear_aspm(struct pci_bus *bus); extern void pcie_no_aspm(void); #else static inline void pcie_aspm_init_link_state(struct pci_dev *pdev) @@ -43,7 +43,7 @@ static inline void pci_disable_link_state(struct pci_dev *pdev, int state) { } -static inline void pcie_clear_aspm(void) +static inline void pcie_clear_aspm(struct pci_bus *bus) { } static inline void pcie_no_aspm(void)