pci: completely disable aspm if it's unsupported

Commit Message

Pavel Machek Dec. 3, 2015, 10:40 p.m. UTC

Hi!

> We have some hardware that takes about 30 seconds to setup common clocks for
> ASPM, but our bios'es don't actually allow ASPM.  It seems we had this thing in
> place where we would disable ASPM after the pci bus probe so that we would make
> sure that pre pcie 1.1 devices would be properly skipped during initialization.
> This is because the mechanism to disable ASPM doesn't actually disable the
> setting up of the link state stuff, it just keeps us from changing the link
> state after the fact.  So instead make it so that when we call pcie_no_aspm()
> that we disable ASPM completley, that is we skip setting up the link state and
> everything.  This way we avoid the costly setup for a feature we cannot support
> in the first place and we also make sure we are safe from future tampering with
> the ASPM link state.  Thanks,

On thinkpad x60, I have similar problem.

I'm carying this for long long time now:

Patch

diff --git a/drivers/pci/pci-acpi.c b/drivers/pci/pci-acpi.c
index a32ba75..5eb7621 100644
--- a/drivers/pci/pci-acpi.c
+++ b/drivers/pci/pci-acpi.c
@@ -700,7 +700,7 @@  static int __init acpi_pci_init(void)
 
 	if (acpi_gbl_FADT.boot_flags & ACPI_FADT_NO_ASPM) {
 		pr_info("ACPI FADT declares the system doesn't support PCIe ASPM, so disable it\n");
-		pcie_no_aspm();
+//		pcie_no_aspm();
 	}
 
 	ret = register_acpi_bus_type(&acpi_pci_bus);