Re: [PATCH v4] ACPI: Fix osc flag setup ordering to allow pciehotplug use when available

[Yinghai Lu]

On Thu, Aug 29, 2013 at 1:17 PM, Neil Horman <nhorman@xxxxxxxxxxxxx> wrote:
> This is a fix for:
> https://bugzilla.kernel.org/show_bug.cgi?id=60736
>
> During the 3.8 devel cycle:
>
> commit 8c33f51df406e1a1f7fa4e9b244845b7ebd61fa6
> Author: Taku Izumi <izumi.taku@xxxxxxxxxxxxxx>
> Date:   Tue Oct 30 15:27:13 2012 +0900
>
>     PCI/ACPI: Request _OSC control before scanning PCI root bus
>
> went in to allow us to query the pcie hotplug flags during the acpi bus scan.
> It however caused problems with the disabling of pcie aspm, and so:
> commit b8178f130e25c1bdac1c33e0996f1ff6e20ec08e
> Author: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
> Date:   Mon Apr 1 15:47:39 2013 -0600
>
>     Revert "PCI/ACPI: Request _OSC control before scanning PCI root bus"
>
> Backed it out.  This of course brought back the problem in which acpi took over
> hotplug ports that were meant to be controlled by pcie.
>
> This patch gives us both items.  It lets us request _OSC control before scanning
> the pci root bus, but defers any disabling of aspm until after the scan is
> complete, allowing us to properly handle old pcie 1.1 devices aspm settings
> properly, as b8178f130e documents.
>
> Tested successfully by myself.
>
> Signed-off-by: Neil Horman <nhorman@xxxxxxxxxxxxx>
> CC: Len Brown <lenb@xxxxxxxxxx>
> CC: "Rafael J. Wysocki" <rjw@xxxxxxx>
> CC: linux-acpi@xxxxxxxxxxxxxxx
> CC: linux-pci@xxxxxxxxxxxxxxx
> ---
>  drivers/acpi/pci_root.c | 62 ++++++++++++++++++++++++++++++-------------------
>  1 file changed, 38 insertions(+), 24 deletions(-)
>
> diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
> index 5917839..6110fd2 100644
> --- a/drivers/acpi/pci_root.c
> +++ b/drivers/acpi/pci_root.c
> @@ -378,6 +378,7 @@ static int acpi_pci_root_add(struct acpi_device *device,
>         struct acpi_pci_root *root;
>         u32 flags, base_flags;
>         acpi_handle handle = device->handle;
> +       bool no_aspm = false, clear_aspm = false;
>
>         root = kzalloc(sizeof(struct acpi_pci_root), GFP_KERNEL);
>         if (!root)
> @@ -437,27 +438,6 @@ 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.
> -        */
> -
> -       /*
> -        * 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) {
> -               dev_err(&device->dev,
> -                       "Bus %04x:%02x not present in PCI namespace\n",
> -                       root->segment, (unsigned int)root->secondary.start);
> -               result = -ENODEV;
> -               goto end;
> -       }
> -
> -       /* Indicate support for various _OSC capabilities. */
>         if (pci_ext_cfg_avail())
>                 flags |= OSC_EXT_PCI_CONFIG_SUPPORT;
>         if (pcie_aspm_support_enabled()) {
> @@ -471,7 +451,7 @@ static int acpi_pci_root_add(struct acpi_device *device,
>                 if (ACPI_FAILURE(status)) {
>                         dev_info(&device->dev, "ACPI _OSC support "
>                                 "notification failed, disabling PCIe ASPM\n");
> -                       pcie_no_aspm();
> +                       no_aspm = true;
>                         flags = base_flags;
>                 }
>         }
> @@ -503,7 +483,7 @@ static int acpi_pci_root_add(struct acpi_device *device,
>                                  * We have ASPM control, but the FADT indicates
>                                  * that it's unsupported. Clear it.
>                                  */
> -                               pcie_clear_aspm(root->bus);
> +                               clear_aspm = true;
>                         }
>                 } else {
>                         dev_info(&device->dev,
> @@ -512,7 +492,14 @@ static int acpi_pci_root_add(struct acpi_device *device,
>                                 acpi_format_exception(status), flags);
>                         dev_info(&device->dev,
>                                  "ACPI _OSC control for PCIe not granted, disabling ASPM\n");
> -                       pcie_no_aspm();
> +                       /*
> +                        * We want to disable aspm here, but aspm_disabled
> +                        * needs to remain in its state from boot so that we
> +                        * properly handle pcie 1.1 devices.  So we set this
> +                        * flag here, to defer the action until after the acpi
> +                        * root scan
> +                        */
> +                       no_aspm = true;
>                 }
>         } else {
>                 dev_info(&device->dev,
> @@ -520,6 +507,33 @@ 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.
> +        */
> +
> +       /*
> +        * 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) {
> +               dev_err(&device->dev,
> +                       "Bus %04x:%02x not present in PCI namespace\n",
> +                       root->segment, (unsigned int)root->secondary.start);
> +               result = -ENODEV;
> +               goto end;
> +       }
> +
> +       if (clear_aspm) {
> +               dev_info(&device->dev, "Disabling ASPM (FADT indicates it is unsupported)\n");
> +               pcie_clear_aspm(root->bus);
> +       }
> +       if (no_aspm)
> +               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);

Also need to cc stable?

Acked-by: Yinghai Lu <yinghai@xxxxxxxxxx>
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