• Mario Limonciello's avatar
    ACPI: Execute platform _OSC also with query bit clear · 719e1f56
    Mario Limonciello authored
    The platform _OSC can change the hardware state when query bit is not
    set. According to ACPI spec it is recommended that the OS runs _OSC with
    query bit set until the platform does not mask any of the capabilities.
    Then it should run it with query bit clear in order to actually commit
    the changes. Linux has not been doing this for the reasons that there
    has not been anything to commit, until now.
    
    The ACPI 6.4 introduced _OSC for USB4 to allow the OS to negotiate
    native control over USB4 tunneling. The platform might implement this so
    that it only activates the software connection manager path when the OS
    calls the _OSC with the query bit clear. Otherwise it may default to the
    firmware connection manager, for instance.
    
    For this reason modify the _OSC support so that we first execute it with
    query bit set, then use the returned value as base of the features we
    want to control and run the _OSC again with query bit clear. This also
    follows what Windows is doing.
    
    Also rename the function to better match what it does.
    Signed-off-by: default avatarMario Limonciello <mario.limonciello@dell.com>
    Acked-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
    Signed-off-by: default avatarMika Westerberg <mika.westerberg@linux.intel.com>
    719e1f56
bus.c 33.7 KB