Commit 508d392a authored Jun 02, 2020 by Bjorn Helgaas

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>

parent 866e61fc

drivers/acpi/pci_root.c

+3 −4

Original line number	Diff line number	Diff line
		@@ -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));

		/*