• Rafael J. Wysocki's avatar
    PM / sleep: Re-implement suspend-to-idle handling · 38106313
    Rafael J. Wysocki authored
    
    
    In preparation for adding support for quiescing timers in the final
    stage of suspend-to-idle transitions, rework the freeze_enter()
    function making the system wait on a wakeup event, the freeze_wake()
    function terminating the suspend-to-idle loop and the mechanism by
    which deep idle states are entered during suspend-to-idle.
    
    First of all, introduce a simple state machine for suspend-to-idle
    and make the code in question use it.
    
    Second, prevent freeze_enter() from losing wakeup events due to race
    conditions and ensure that the number of online CPUs won't change
    while it is being executed.  In addition to that, make it force
    all of the CPUs re-enter the idle loop in case they are in idle
    states already (so they can enter deeper idle states if possible).
    
    Next, drop cpuidle_use_deepest_state() and replace use_deepest_state
    checks in cpuidle_select() and cpuidle_reflect() with a single
    suspend-to-idle state check in cpuidle_idle_call().
    
    Finally, introduce cpuidle_enter_freeze() that will simply find the
    deepest idle state available to the given CPU and enter it using
    cpuidle_enter().
    
    Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
    Acked-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
    38106313