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PCI/ACPI: correct error message for ASPM disabling

PATCH In review Sinan Kaya 3 participants 4 messages Aug 10, 2018 – Sep 6, 2018

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ACPI PCI
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Sinan Kaya

author
#0 lore raw

PATCH v2 1/2 PCI/ACPI: correct error message for ASPM disabling

If _OSC execution fails today for platforms without an _OSC entry, code is printing a misleading message saying disabling ASPM as follows:

acpi PNP0A03:00: _OSC failed (AE_NOT_FOUND); disabling ASPM

We need to ensure that platform supports ASPM to begin with.

Signed-off-by Sinan Kaya <[email protected]>
Reported-by Michael Kelley <[email protected]>
---
 drivers/acpi/pci_root.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)
drivers/acpi/pci_root.c +3 -2
index 7433035..e465e72 100644
@@ -455,8 +455,9 @@ static void negotiate_os_control(struct acpi_pci_root *root, int *no_aspm)
 	decode_osc_support(root, "OS supports", support);
 	status = acpi_pci_osc_support(root, support);
 	if (ACPI_FAILURE(status)) {
-		dev_info(&device->dev, "_OSC failed (%s); disabling ASPM\n",
-			 acpi_format_exception(status));
+		dev_info(&device->dev, "_OSC failed (%s)%s\n",
+			 acpi_format_exception(status),
+			 pcie_aspm_support_enabled() ? "; disabling ASPM" : "");
 		*no_aspm = 1;
 		return;
 	}
Signature · 1 line
2.7.4
author
#1 lore raw

PATCH v2 2/2 PCI/ACPI: allow _OSC presence to be optional for PCI

ACPI Spec 6.0 Section 6.2.11.3 OSC Implementation Example for PCI Host Bridge Devices:

For a host bridge device that originates a PCI Express hierarchy, the _OSC interface defined in this section is required.

For a host bridge device that originates a PCI/PCI-X bus hierarchy, inclusion of an _OSC object is optional.

Allow PCI host bridges to bail out silently if _OSC is not found.

Signed-off-by Sinan Kaya <[email protected]>
Reported-by Michael Kelley <[email protected]>
---
 drivers/acpi/pci_root.c | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)
drivers/acpi/pci_root.c +11 -3
index e465e72..707aafc 100644
@@ -421,7 +421,8 @@ acpi_status acpi_pci_osc_control_set(acpi_handle handle, u32 *mask, u32 req)
 }
 EXPORT_SYMBOL(acpi_pci_osc_control_set);
 
-static void negotiate_os_control(struct acpi_pci_root *root, int *no_aspm)
+static void negotiate_os_control(struct acpi_pci_root *root, int *no_aspm,
+				 bool is_pcie)
 {
 	u32 support, control, requested;
 	acpi_status status;

@@ -455,10 +456,15 @@ static void negotiate_os_control(struct acpi_pci_root *root, int *no_aspm)
 	decode_osc_support(root, "OS supports", support);
 	status = acpi_pci_osc_support(root, support);
 	if (ACPI_FAILURE(status)) {
+		*no_aspm = 1;
+
+		/* _OSC is optional for PCI host bridges */
+		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" : "");
-		*no_aspm = 1;
 		return;
 	}
 

@@ -534,6 +540,7 @@ static int acpi_pci_root_add(struct acpi_device *device,
 	acpi_handle handle = device->handle;
 	int no_aspm = 0;
 	bool hotadd = system_state == SYSTEM_RUNNING;
+	bool is_pcie;
 
 	root = kzalloc(sizeof(struct acpi_pci_root), GFP_KERNEL);
 	if (!root)

@@ -591,7 +598,8 @@ static int acpi_pci_root_add(struct acpi_device *device,
 
 	root->mcfg_addr = acpi_pci_root_get_mcfg_addr(handle);
 
-	negotiate_os_control(root, &no_aspm);
+	is_pcie = strcmp(acpi_device_hid(device), "PNP0A08") == 0;
+	negotiate_os_control(root, &no_aspm, is_pcie);
 
 	/*
 	 * TBD: Need PCI interface for enumeration/configuration of roots.
Signature · 1 line
2.7.4
#2 lore raw
In reply to Sinan Kaya
Quoted 10 lines · Sinan Kaya

If _OSC execution fails today for platforms without an _OSC entry, code is printing a misleading message saying disabling ASPM as follows:

acpi PNP0A03:00: _OSC failed (AE_NOT_FOUND); disabling ASPM

We need to ensure that platform supports ASPM to begin with.

Signed-off-by Sinan Kaya <[email protected]>
Reported-by Michael Kelley <[email protected]>

Tentatively applied both to pci/aspm for v4.20, thanks!

Rafael, let me know if you object or would rather put these through your tree.

Quoted 23 lines
---
 drivers/acpi/pci_root.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)
drivers/acpi/pci_root.c +3 -2
index 7433035..e465e72 100644
@@ -455,8 +455,9 @@ static void negotiate_os_control(struct acpi_pci_root *root, int *no_aspm)
 	decode_osc_support(root, "OS supports", support);
 	status = acpi_pci_osc_support(root, support);
 	if (ACPI_FAILURE(status)) {
-		dev_info(&device->dev, "_OSC failed (%s); disabling ASPM\n",
-			 acpi_format_exception(status));
+		dev_info(&device->dev, "_OSC failed (%s)%s\n",
+			 acpi_format_exception(status),
+			 pcie_aspm_support_enabled() ? "; disabling ASPM" : "");
 		*no_aspm = 1;
 		return;
 	}
Signature · 1 line
2.7.4
maintainer
#3 lore raw
Quoted 8 lines · Bjorn Helgaas
Quoted 6 lines · Sinan Kaya

If _OSC execution fails today for platforms without an _OSC entry, code is printing a misleading message saying disabling ASPM as follows:

acpi PNP0A03:00: _OSC failed (AE_NOT_FOUND); disabling ASPM

Quoted 8 lines
Quoted 4 lines

We need to ensure that platform supports ASPM to begin with.

Signed-off-by Sinan Kaya <[email protected]>
Reported-by Michael Kelley <[email protected]>

Tentatively applied both to pci/aspm for v4.20, thanks!

Rafael, let me know if you object or would rather put these through your tree.

I have no problems with these and they can go in via the PCI tree as far as I'm concerned.

Thanks,
Rafael