• Rafael J. Wysocki's avatar
    cpuidle: Do not use CPUIDLE_DRIVER_STATE_START in cpuidle.c · 7d51d979
    Rafael J. Wysocki authored
    
    
    The CPUIDLE_DRIVER_STATE_START symbol is defined as 1 only if
    CONFIG_ARCH_HAS_CPU_RELAX is set, otherwise it is defined as 0.
    However, if CONFIG_ARCH_HAS_CPU_RELAX is set, the first (index 0)
    entry in the cpuidle driver's table of states is overwritten with
    the default "poll" entry by the core.  The "state" defined by the
    "poll" entry doesn't provide ->enter_dead and ->enter_freeze
    callbacks and its exit_latency is 0.
    
    For this reason, it is not necessary to use CPUIDLE_DRIVER_STATE_START
    in cpuidle_play_dead() (->enter_dead is NULL, so the "poll state"
    will be skipped by the loop).
    
    It also is arguably unuseful to return states with exit_latency
    equal to 0 from find_deepest_state(), so the function can be modified
    to start the loop from index 0 and the "poll state" will be skipped by
    it as a result of the check against latency_req.
    
    Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
    Reviewed-by: default avatarPreeti U Murthy <preeti@linux.vnet.ibm.com>
    7d51d979