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>

2 files changed, 12 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>