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    PCI: PCIe: Ask BIOS for control of all native services at once · 28eb5f27
    Rafael J. Wysocki 提交于
    After commit 852972ac (ACPI: Disable
    ASPM if the platform won't provide _OSC control for PCIe) control of
    the PCIe Capability Structure is unconditionally requested by
    acpi_pci_root_add(), which in principle may cause problems to
    happen in two ways.  First, the BIOS may refuse to give control of
    the PCIe Capability Structure if it is not asked for any of the
    _OSC features depending on it at the same time.  Second, the BIOS may
    assume that control of the _OSC features depending on the PCIe
    Capability Structure will be requested in the future and may behave
    incorrectly if that doesn't happen.  For this reason, control of
    the PCIe Capability Structure should always be requested along with
    control of any other _OSC features that may depend on it (ie. PCIe
    native PME, PCIe native hot-plug, PCIe AER).
    
    Rework the PCIe port driver so that (1) it checks which native PCIe
    port services can be enabled, according to the BIOS, and (2) it
    requests control of all these services simultaneously.  In
    particular, this causes pcie_portdrv_probe() to fail if the BIOS
    refuses to grant control of the PCIe Capability Structure, which
    means that no native PCIe port services can be enabled for the PCIe
    Root Complex the given port belongs to.  If that happens, ASPM is
    disabled to avoid problems with mishandling it by the part of the
    PCIe hierarchy for which control of the PCIe Capability Structure
    has not been received.
    
    Make it possible to override this behavior using 'pcie_ports=native'
    (use the PCIe native services regardless of the BIOS response to the
    control request), or 'pcie_ports=compat' (do not use the PCIe native
    services at all).
    
    Accordingly, rework the existing PCIe port service drivers so that
    they don't request control of the services directly.
    Signed-off-by: NRafael J. Wysocki <rjw@sisk.pl>
    Signed-off-by: NJesse Barnes <jbarnes@virtuousgeek.org>
    28eb5f27
pci_root.c 15.7 KB