• Rafael J. Wysocki's avatar
    ACPI / ACPICA: Do not execute _PRW methods during initialization · 9874647b
    Rafael J. Wysocki authored
    Currently, during initialization ACPICA walks the entire ACPI
    namespace in search of any device objects with assciated _PRW
    methods.  All of the _PRW methods found are executed in the process
    to extract the GPE information returned by them, so that the GPEs in
    question can be marked as "able to wakeup" (more precisely, the
    ACPI_GPE_CAN_WAKE flag is set for them).  The only purpose of this
    exercise is to avoid enabling the CAN_WAKE GPEs automatically, even
    if there are _Lxx/_Exx methods associated with them.  However, it is
    both costly and unnecessary, because the host OS has to execute the
    _PRW methods anyway to check which devices can wake up the system
    from sleep states.  Moreover, it then uses full information
    returned by _PRW, including the GPE information, so it can take care
    of disabling the GPEs if necessary.
    
    Remove the code that walks the namespace and executes _PRW from
    ACPICA and modify comments to reflect that change.  Make
    acpi_bus_set_run_wake_flags() disable GPEs for wakeup devices
    so that they don't cause spurious wakeup events to be signaled.
    This not only reduces the complexity of the ACPICA initialization
    code, but in some cases it should reduce the kernel boot time as
    well.
    
    Unfortunately, for this purpose we need a new ACPICA function,
    acpi_gpe_can_wake(), to be called by the host OS in order to disable
    the GPEs that can wake up the system and were previously enabled by
    acpi_ev_initialize_gpe_block() or acpi_ev_update_gpes() (such a GPE
    should be disabled only once, because the initialization code enables
    it only once, but it may be pointed to by _PRW for multiple devices
    and that's why the additional function is necessary).
    Signed-off-by: default avatarRafael J. Wysocki <rjw@sisk.pl>
    Signed-off-by: default avatarLen Brown <len.brown@intel.com>
    9874647b
scan.c 38.6 KB