PCI: disable ASPM on pre-1.1 PCIe devices

Disable ASPM on pre-1.1 PCIe devices, as many of them don't implement it
correctly.

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>

1 files changed, 13 insertions, 0 deletions

diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c
index 759c51a4e399..704605298c5e 100644
--- a/drivers/pci/pcie/aspm.c
+++ b/drivers/pci/pcie/aspm.c
@@ -510,6 +510,7 @@ static int pcie_aspm_sanity_check(struct pci_dev *pdev)
 {
         struct pci_dev *child_dev;
         int child_pos;
+        u32 reg32;
 
         /*
          * Some functions in a slot might not all be PCIE functions, very
@@ -519,6 +520,18 @@ static int pcie_aspm_sanity_check(struct pci_dev *pdev)
                 child_pos = pci_find_capability(child_dev, PCI_CAP_ID_EXP);
                 if (!child_pos)
                         return -EINVAL;
+
+                /*
+                 * Disable ASPM for pre-1.1 PCIe device, we follow MS to use
+                 * RBER bit to determine if a function is 1.1 version device
+                 */
+                pci_read_config_dword(child_dev, child_pos + PCI_EXP_DEVCAP,
+                        &reg32);
+                if (!(reg32 & PCI_EXP_DEVCAP_RBER)) {
+                        printk("Pre-1.1 PCIe device detected, "
+                                "disable ASPM for %s\n", pci_name(pdev));
+                        return -EINVAL;
+                }
         }
         return 0;
 }