On Friday, September 06, 2013 11:13:24 AM Bjorn Helgaas wrote:
> This is a long series of mostly minor changes with the goal of
> simplifying the _OSC-related code and making the negotiation between
> Linux and the platform more understandable.
>
> My intent is that this doesn't change any behavior except for the text
> in dmesg.
>
> However, this restructuring does raise some questions in my mind, such
> as the fact that we do not call pcie_no_aspm() to disable ASPM in two
> cases where it seems like we might want to:
>
> 1) When pcie_ports_disabled, e.g., when booting with
> "pcie_ports=compat".
>
> 2) When Linux doesn't support all the required services, e.g., if
> compiled with ASPM support but not MSI support.
>
> I haven't looked deeply, so maybe there are other constraints that
> keep us from using ASPM in these cases. In any case, this series
> doesn't change any behavior in this regard.
>
> Below are samples of the dmesg changes from this series. Typical case
> where we successfully get control of PCIe services:
>
> -acpi PNP0A08:00: Requesting ACPI _OSC control (0x1d)
> -acpi PNP0A08:00: ACPI _OSC control (0x1d) granted
> +acpi PNP0A08:00: _OSC: OS supports [ExtendedConfig ASPM ClockPM Segments MSI]
> +acpi PNP0A08:00: _OSC: OS now controls [PCIeHotplug PME AER PCIeCapability]
>
> Failure case where the system has no _OSC method:
>
> -acpi PNP0A03:00: ACPI _OSC support notification failed, disabling PCIe ASPM
> -acpi PNP0A03:00: Unable to request _OSC control (_OSC support mask: 0x08)
> +acpi PNP0A03:00: _OSC: OS supports [ASPM ClockPM Segments MSI]
> +acpi PNP0A03:00: _OSC failed (AE_NOT_FOUND); disabling ASPM
>
> Linux only requests _OSC control of features as a group; if Linux
> doesn't support *all* of those features, we don't request control of
> any of them (per 415e12b237). Here's an example booted with
> "pci=nomsi":
>
> -acpi PNP0A08:00: Unable to request _OSC control (_OSC support mask: 0x0f)
> +acpi PNP0A08:00: _OSC: OS supports [ExtendedConfig ASPM ClockPM Segments]
> +acpi PNP0A08:00: _OSC: not requesting OS control; OS requires [ExtendedConfig ASPM ClockPM MSI]
>
> Here's a system that doesn't grant OS control of the PCIe Capability.
> This is another case where we don't want control of anything unless we
> have control of the PCIe Capability:
>
> -acpi PNP0A08:00: Requesting ACPI _OSC control (0x1d)
> -acpi PNP0A08:00: ACPI _OSC request failed (AE_SUPPORT), returned control mask: 0x0d
> -acpi PNP0A08:00: ACPI _OSC control for PCIe not granted, disabling ASPM
> +acpi PNP0A08:00: _OSC: OS supports [ExtendedConfig ASPM ClockPM Segments MSI]
> +acpi PNP0A08:00: _OSC: platform does not support [PCIeCapability]
> +acpi PNP0A08:00: _OSC: not requesting control; platform does not support [PCIeCapability]
> +acpi PNP0A08:00: _OSC: OS requested [PCIeHotplug PME AER PCIeCapability]
> +acpi PNP0A08:00: _OSC: platform willing to grant [PCIeHotplug PME AER]
> +acpi PNP0A08:00: _OSC failed (AE_SUPPORT); disabling ASPM
>
>
> This is based on a923874198 ("Merge tag 'pci-v3.12-changes' of
> git://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci").
>
> ---
>
> Bjorn Helgaas (14):
> ACPI: Write _OSC bit field definitions in hex
> ACPI: Rename OSC_QUERY_TYPE to OSC_QUERY_DWORD
> ACPI: Tidy acpi_run_osc() declarations
> ACPI: Remove unused OSC_PCI_NATIVE_HOTPLUG
> ACPI: Write OSC_PCI_CONTROL_MASKS like OSC_PCI_SUPPORT_MASKS
> PCI/ACPI: Name _OSC #defines more consistently
> PCI/ACPI: Drop unnecessary _OSC existence tests
> PCI/ACPI: Move _OSC stuff from acpi_pci_root_add() to negotiate_os_control()
> PCI/ACPI: Split _OSC "support" and "control" flags into separate variables
> PCI/ACPI: Run _OSC only once for OSPM feature support
> PCI/ACPI: Skip _OSC control tests if _OSC support call failed
> PCI/ACPI: Separate out _OSC "PCIe port services disabled" path
> PCI/ACPI: Separate out _OSC "we don't support enough services" path
> PCI/ACPI: Decode _OSC bitmasks symbolically
Please feel free to add
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
to the entire series.
Thanks,
Rafael
--
To unsubscribe from this list: send the line "unsubscribe linux-pci" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
