linux-kernel - [PATCH 3/3] PCI/ACPI: Clarify message about

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Date:   Tue, 26 Jan 2021 16:03:11 -0600
From:   Bjorn Helgaas <helgaas@...nel.org>
To:     "Rafael J . Wysocki" <rjw@...ysocki.net>,
        Len Brown <lenb@...nel.org>
Cc:     Sinan Kaya <okaya@...nel.org>,
        Yicong Yang <yangyicong@...ilicon.com>,
        Sean V Kelley <sean.v.kelley@...el.com>,
        linux-pci@...r.kernel.org, linux-acpi@...r.kernel.org,
        linux-kernel@...r.kernel.org, Bjorn Helgaas <bhelgaas@...gle.com>
Subject: [PATCH 3/3] PCI/ACPI: Clarify message about _OSC failure

From: Bjorn Helgaas <bhelgaas@...gle.com>

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@...gle.com>
Reviewed-by: Sinan Kaya <okaya@...nel.org>
Cc: Yicong Yang <yangyicong@...ilicon.com>
---
 drivers/acpi/pci_root.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
index a001f8f56b4b..6950a35a5ac7 100644
--- 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));
 
 		/*
-- 
2.25.1