• Srivatsa S. Bhat's avatar
    cpufreq: powernow-k6: Fix double invocation of cpufreq_freq_transition_begin/end · 3221e55b
    Srivatsa S. Bhat authored
    During frequency transitions, the cpufreq core takes the responsibility of
    invoking cpufreq_freq_transition_begin() and cpufreq_freq_transition_end()
    for those cpufreq drivers that define the ->target_index callback but don't
    set the ASYNC_NOTIFICATION flag.
    
    The powernow-k6 cpufreq driver falls under this category, but this driver was
    invoking the _begin() and _end() APIs itself around frequency transitions,
    which led to double invocation of the _begin() API. The _begin API makes
    contending callers wait until the previous invocation is complete. Hence,
    the powernow-k6 driver ended up waiting on itself, leading to system hangs
    during boot.
    
    Fix this by removing the calls to the _begin() and _end() APIs from the
    powernow-k6 driver, since they rightly belong to the cpufreq core.
    
    (Note that during ->exit(), the powernow-k6 driver sets the frequency
     without any help from the cpufreq core. So add explicit calls to the
     _begin() and _end() APIs around that frequency transition alone, to take
     care of that special case. Also, add a missing 'break' statement there.)
    
    Fixes: 12478cf0 (cpufreq: Make sure frequency transitions are serialized)
    Signed-off-by: default avatarSrivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
    Acked-by: default avatarViresh Kumar <viresh.kumar@linaro.org>
    Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
    3221e55b
powernow-k6.c 8.21 KB