PCI: disable ASPM per ACPI FADT setting

The ACPI FADT table includes an ASPM control bit. If the bit is set, do
not enable ASPM since it may indicate that the platform doesn't actually
support the feature.

Tested-by: Jack Howarth <howarth@bromo.msbb.uc.edu>
Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

4 files changed, 18 insertions, 0 deletions

diff --git a/drivers/pci/pci-acpi.c b/drivers/pci/pci-acpi.c
index 7764768b6a0e..89a2f0fa10f9 100644
--- a/drivers/pci/pci-acpi.c
+++ b/drivers/pci/pci-acpi.c
@@ -11,6 +11,7 @@
 #include <linux/init.h>
 #include <linux/pci.h>
 #include <linux/module.h>
+#include <linux/pci-aspm.h>
 #include <acpi/acpi.h>
 #include <acpi/acnamesp.h>
 #include <acpi/acresrc.h>
@@ -372,6 +373,12 @@ static int __init acpi_pci_init(void)
                 printk(KERN_INFO"ACPI FADT declares the system doesn't support MSI, so disable it\n");
                 pci_no_msi();
         }
+
+        if (acpi_gbl_FADT.boot_flags & BAF_PCIE_ASPM_CONTROL) {
+                printk(KERN_INFO"ACPI FADT declares the system doesn't support PCIe ASPM, so disable it\n");
+                pcie_no_aspm();
+        }
+
         ret = register_acpi_bus_type(&acpi_pci_bus);
         if (ret)
                 return 0;
diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c
index f82495583e63..759c51a4e399 100644
--- a/drivers/pci/pcie/aspm.c
+++ b/drivers/pci/pcie/aspm.c
@@ -808,6 +808,11 @@ static int __init pcie_aspm_disable(char *str)
 
 __setup("pcie_noaspm", pcie_aspm_disable);
 
+void pcie_no_aspm(void)
+{
+        aspm_disabled = 1;
+}
+
 #ifdef CONFIG_ACPI
 #include <acpi/acpi_bus.h>
 #include <linux/pci-acpi.h>
diff --git a/include/acpi/actbl.h b/include/acpi/actbl.h
index 1ebbe883f786..13a3d9ad92db 100644
--- a/include/acpi/actbl.h
+++ b/include/acpi/actbl.h
@@ -277,6 +277,7 @@ enum acpi_prefered_pm_profiles {
 #define BAF_LEGACY_DEVICES              0x0001
 #define BAF_8042_KEYBOARD_CONTROLLER    0x0002
 #define BAF_MSI_NOT_SUPPORTED           0x0008
+#define BAF_PCIE_ASPM_CONTROL           0x0010
 
 #define FADT2_REVISION_ID               3
 #define FADT2_MINUS_REVISION_ID         2
diff --git a/include/linux/pci-aspm.h b/include/linux/pci-aspm.h
index a1a1e618e996..91ba0b338b47 100644
--- a/include/linux/pci-aspm.h
+++ b/include/linux/pci-aspm.h
@@ -27,6 +27,7 @@ extern void pcie_aspm_init_link_state(struct pci_dev *pdev);
 extern void pcie_aspm_exit_link_state(struct pci_dev *pdev);
 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 pcie_no_aspm(void);
 #else
 static inline void pcie_aspm_init_link_state(struct pci_dev *pdev)
 {
@@ -40,6 +41,10 @@ static inline void pcie_aspm_pm_state_change(struct pci_dev *pdev)
 static inline void pci_disable_link_state(struct pci_dev *pdev, int state)
 {
 }
+
+static inline void pcie_no_aspm(void)
+{
+}
 #endif
 
 #ifdef CONFIG_PCIEASPM_DEBUG /* this depends on CONFIG_PCIEASPM */