Commit b8178f13 authored by Bjorn Helgaas's avatar Bjorn Helgaas
Browse files

Revert "PCI/ACPI: Request _OSC control before scanning PCI root bus" 

This reverts commit 8c33f51d.

Conflicts:
	drivers/acpi/pci_root.c

This commit broke some pre-1.1 PCIe devices by leaving them with
ASPM enabled.  Previously, we had disabled ASPM on these devices
because many of them don't implement it correctly (per 149e1637).

Requesting _OSC control early means that aspm_disabled may be set
before we scan the PCI bus and configure link ASPM state.  But the
ASPM configuration currently skips the check for pre-PCIe 1.1 devices
when aspm_disabled is set, like this:

    acpi_pci_root_add
      acpi_pci_osc_support
        if (flags != base_flags)
          pcie_no_aspm
            aspm_disabled = 1
      pci_acpi_scan_root
        ...
          pcie_aspm_init_link_state
            pcie_aspm_sanity_check
              if (!aspm_disabled)
                /* check for pre-PCIe 1.1 device */

Therefore, setting aspm_disabled early means that we leave ASPM enabled
on these pre-PCIe 1.1 devices, which is a regression for some devices.

The best fix would be to clean up the ASPM init so we can evaluate
_OSC before scanning the bug (that way boot-time and hot-add discovery
will work the same), but that requires significant rework.

For now, we'll just revert the _OSC change as the lowest-risk fix.

Reference: https://bugzilla.kernel.org/show_bug.cgi?id=55211


Signed-off-by: default avatarBjorn Helgaas <bhelgaas@google.com>
Acked-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: default avatarYinghai Lu <yinghai@kernel.org>
CC: stable@vger.kernel.org	# v3.8+
parent be7f088b

drivers/acpi/pci_root.c

+37 −39
Original line number Diff line number Diff line
@@ -415,7 +415,6 @@ static int acpi_pci_root_add(struct acpi_device *device, 
	struct acpi_pci_root *root;

	struct acpi_pci_driver *driver;

	u32 flags, base_flags;

	bool is_osc_granted = false;



	root = kzalloc(sizeof(struct acpi_pci_root), GFP_KERNEL);

	if (!root)
@@ -476,6 +475,30 @@ static int acpi_pci_root_add(struct acpi_device *device, 
	flags = base_flags = OSC_PCI_SEGMENT_GROUPS_SUPPORT;

	acpi_pci_osc_support(root, flags);



	/*

	 * TBD: Need PCI interface for enumeration/configuration of roots.

	 */



	mutex_lock(&acpi_pci_root_lock);

	list_add_tail(&root->node, &acpi_pci_roots);

	mutex_unlock(&acpi_pci_root_lock);



	/*

	 * Scan the Root Bridge

	 * --------------------

	 * Must do this prior to any attempt to bind the root device, as the

	 * PCI namespace does not get created until this call is made (and

	 * thus the root bridge's pci_dev does not exist).

	 */

	root->bus = pci_acpi_scan_root(root);

	if (!root->bus) {

		printk(KERN_ERR PREFIX

			    "Bus %04x:%02x not present in PCI namespace\n",

			    root->segment, (unsigned int)root->secondary.start);

		result = -ENODEV;

		goto out_del_root;

	}



	/* Indicate support for various _OSC capabilities. */

	if (pci_ext_cfg_avail())

		flags |= OSC_EXT_PCI_CONFIG_SUPPORT;
@@ -494,6 +517,7 @@ static int acpi_pci_root_add(struct acpi_device *device, 
			flags = base_flags;

		}

	}



	if (!pcie_ports_disabled

	    && (flags & ACPI_PCIE_REQ_SUPPORT) == ACPI_PCIE_REQ_SUPPORT) {

		flags = OSC_PCI_EXPRESS_CAP_STRUCTURE_CONTROL
@@ -514,15 +538,23 @@ static int acpi_pci_root_add(struct acpi_device *device, 
		status = acpi_pci_osc_control_set(device->handle, &flags,

				       OSC_PCI_EXPRESS_CAP_STRUCTURE_CONTROL);

		if (ACPI_SUCCESS(status)) {

			is_osc_granted = true;

			dev_info(&device->dev,

				"ACPI _OSC control (0x%02x) granted\n", flags);

			if (acpi_gbl_FADT.boot_flags & ACPI_FADT_NO_ASPM) {

				/*

				 * We have ASPM control, but the FADT indicates

				 * that it's unsupported. Clear it.

				 */

				pcie_clear_aspm(root->bus);

			}

		} else {

			is_osc_granted = false;

			dev_info(&device->dev,

				"ACPI _OSC request failed (%s), "

				"returned control mask: 0x%02x\n",

				acpi_format_exception(status), flags);

			pr_info("ACPI _OSC control for PCIe not granted, "

				"disabling ASPM\n");

			pcie_no_aspm();

		}

	} else {

		dev_info(&device->dev,
@@ -530,40 +562,6 @@ static int acpi_pci_root_add(struct acpi_device *device, 
			 "(_OSC support mask: 0x%02x)\n", flags);

	}



	/*

	 * TBD: Need PCI interface for enumeration/configuration of roots.

	 */



	mutex_lock(&acpi_pci_root_lock);

	list_add_tail(&root->node, &acpi_pci_roots);

	mutex_unlock(&acpi_pci_root_lock);



	/*

	 * Scan the Root Bridge

	 * --------------------

	 * Must do this prior to any attempt to bind the root device, as the

	 * PCI namespace does not get created until this call is made (and 

	 * thus the root bridge's pci_dev does not exist).

	 */

	root->bus = pci_acpi_scan_root(root);

	if (!root->bus) {

		printk(KERN_ERR PREFIX

			    "Bus %04x:%02x not present in PCI namespace\n",

			    root->segment, (unsigned int)root->secondary.start);

		result = -ENODEV;

		goto out_del_root;

	}



	/* ASPM setting */

	if (is_osc_granted) {

		if (acpi_gbl_FADT.boot_flags & ACPI_FADT_NO_ASPM)

			pcie_clear_aspm(root->bus);

	} else {

		pr_info("ACPI _OSC control for PCIe not granted, "

			"disabling ASPM\n");

		pcie_no_aspm();

	}



	pci_acpi_add_bus_pm_notifier(device, root->bus);

	if (device->wakeup.flags.run_wake)

		device_set_run_wake(root->bus->bridge, true);

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