• Viresh Kumar's avatar
    cpufreq: Schedule work for the first-online CPU on resume · c75de0ac
    Viresh Kumar authored
    All CPUs leaving the first-online CPU are hotplugged out on suspend and
    and cpufreq core stops managing them.
    
    On resume, we need to call cpufreq_update_policy() for this CPU's policy
    to make sure its frequency is in sync with cpufreq's cached value, as it
    might have got updated by hardware during suspend/resume.
    
    The policies are always added to the top of the policy-list. So, in
    normal circumstances, CPU 0's policy will be the last one in the list.
    And so the code checks for the last policy.
    
    But there are cases where it will fail. Consider quad-core system, with
    policy-per core. If CPU0 is hotplugged out and added back again, the
    last policy will be on CPU1 :(
    
    To fix this in a proper way, always look for the policy of the first
    online CPU. That way we will be sure that we are calling
    cpufreq_update_policy() for the only CPU that wasn't hotplugged out.
    
    Cc: 3.15+ <stable@vger.kernel.org> # 3.15+
    Fixes: 2f0aea93 ("cpufreq: suspend governors on system suspend/hibernate")
    Reported-by: default avatarSaravana Kannan <skannan@codeaurora.org>
    Signed-off-by: default avatarViresh Kumar <viresh.kumar@linaro.org>
    Acked-by: default avatarSaravana Kannan <skannan@codeaurora.org>
    Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
    c75de0ac
cpufreq.c 64.7 KB