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Date: Thu, 29 Aug 2013 17:40:52 -0600
From: Bjorn Helgaas <bhelgaas@...gle.com>
To: Neil Horman <nhorman@...driver.com>
Cc: linux-kernel@...r.kernel.org, Len Brown <lenb@...nel.org>,
"Rafael J. Wysocki" <rjw@...k.pl>, linux-acpi@...r.kernel.org,
linux-pci@...r.kernel.org
Subject: Re: [PATCH v4] ACPI: Fix osc flag setup ordering to allow pcie
hotplug use when available
On Thu, Aug 29, 2013 at 04:17:05PM -0400, Neil Horman 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@...fujitsu.com>
> 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@...gle.com>
> 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@...driver.com>
> CC: Len Brown <lenb@...nel.org>
> CC: "Rafael J. Wysocki" <rjw@...k.pl>
> CC: linux-acpi@...r.kernel.org
> CC: linux-pci@...r.kernel.org
I added Yinghai's ack and a stable tag and put this in pci/misc
for v3.12. Thanks!
I reworked the changelog because I think the actual cause of the
regression was 3b63aaa70e, not the _OSC commits you mentioned:
8c33f51df4 ("PCI/ACPI: Request _OSC control before scanning PCI root bus")
appeared in v3.8 and broke ASPM but not acpiphp.
b8178f130e ('Revert "PCI/ACPI: Request _OSC control before scanning PCI
root bus"') appeared in v3.9 and fixed ASPM, leaving acpiphp working.
3b63aaa70e ("PCI: acpiphp: Do not use ACPI PCI subdriver mechanism")
appeared in v3.10, and I believe this is what actually broke acpiphp
because it moved the acpiphp initialization earlier, into the bus scan.
in v3.8:
acpi_pci_root_add
acpi_pci_osc_control_set # request OS control
pci_acpi_scan_root # scan bus
acpi_pci_root_start
add_bridge # acpi_pci_driver .add method
...
device_is_managed_by_native_pciehp # OK
in v3.9:
acpi_pci_root_add
pci_acpi_scan_root # scan bus
acpi_pci_osc_control_set # request OS control
add_bridge # acpi_pci_driver .add method
...
device_is_managed_by_native_pciehp # OK
in v3.10:
acpi_pci_root_add
pci_acpi_scan_root # scan bus
...
acpiphp_enumerate_slots
...
device_is_managed_by_native_pciehp # PROBLEM
acpi_pci_osc_control_set # request OS control
So I added a stable tag for v3.10+ only. I'll ask Linus to merge it
directly during the merge window for v3.12, and hopefully it will be
backported to the v3.10 and v3.11 stable trees soon after that.
Bjorn
> ---
> 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);
> --
> 1.8.1.4
>
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