PCI/ACPI: Clarify message about _OSC failure

This message:

  acpi PNP0A08:02: _OSC failed (AE_NOT_FOUND); disabling ASPM

is alarming and slightly misleading.  Per the PCI Firmware Spec, r3.2, sec
4.5.1, _OSC is required for PCIe hierarchies.  If _OSC is absent or fails,
the OS must not attempt to use any of the features defined for _OSC.  That
includes native hotplug, native PME, AER, and other things as well as ASPM.

Rephrase the message to:

  acpi PNP0A08:02: _OSC: platform retains control of PCIe features (AE_NOT_FOUND)

Previous discussion at https://lore.kernel.org/r/20200602223618.GA845676@bjorn-Precision-5520/

Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Sinan Kaya <okaya@kernel.org>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Yicong Yang <yangyicong@hisilicon.com>

diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
index ea08b32..dcd5937 100644 (file)
--- a/drivers/acpi/pci_root.c
+++ b/drivers/acpi/pci_root.c
@@ -441,9 +441,8 @@ static void negotiate_os_control(struct acpi_pci_root *root, int *no_aspm,
                if ((status == AE_NOT_FOUND) && !is_pcie)
                        return;
 
-               dev_info(&device->dev, "_OSC failed (%s)%s\n",
-                        acpi_format_exception(status),
-                        pcie_aspm_support_enabled() ? "; disabling ASPM" : "");
+               dev_info(&device->dev, "_OSC: platform retains control of PCIe features (%s)\n",
+                        acpi_format_exception(status));
                return;
        }
 
@@ -499,7 +498,7 @@ static void negotiate_os_control(struct acpi_pci_root *root, int *no_aspm,
        } else {
                decode_osc_control(root, "OS requested", requested);
                decode_osc_control(root, "platform willing to grant", control);
-               dev_info(&device->dev, "_OSC failed (%s); disabling ASPM\n",
+               dev_info(&device->dev, "_OSC: platform retains control of PCIe features (%s)\n",
                        acpi_format_exception(status));
 
                /*