• Rafael J. Wysocki's avatar
    ACPI/PCI: Negotiate _OSC control bits before requesting them · 75fb60f2
    Rafael J. Wysocki authored
    It is possible that the BIOS will not grant control of all _OSC
    features requested via acpi_pci_osc_control_set(), so it is
    recommended to negotiate the final set of _OSC features with the
    query flag set before calling _OSC to request control of these
    features.
    
    To implement it, rework acpi_pci_osc_control_set() so that the caller
    can specify the mask of _OSC control bits to negotiate and the mask
    of _OSC control bits that are absolutely necessary to it.  Then,
    acpi_pci_osc_control_set() will run _OSC queries in a loop until
    the mask of _OSC control bits returned by the BIOS is equal to the
    mask passed to it.  Also, before running the _OSC request
    acpi_pci_osc_control_set() will check if the caller's required
    control bits are present in the final mask.
    
    Using this mechanism we will be able to avoid situations in which the
    BIOS doesn't grant control of certain _OSC features, because they
    depend on some other _OSC features that have not been requested.
    Signed-off-by: default avatarRafael J. Wysocki <rjw@sisk.pl>
    Signed-off-by: default avatarJesse Barnes <jbarnes@virtuousgeek.org>
    75fb60f2
pcie_pme_acpi.c 1.51 KB