• Andreas Herrmann's avatar
    Revert "cpufreq: pcc-cpufreq: update default value of cpuinfo_transition_latency" · da7d3abe
    Andreas Herrmann authored
    This reverts commit 790d849b.
    
    Using a v4.7-rc7 kernel on a HP ProLiant triggered following messages
    
     pcc-cpufreq: (v1.10.00) driver loaded with frequency limits: 1200 MHz, 2800 MHz
     cpufreq: ondemand governor failed, too long transition latency of HW, fallback to performance governor
    
    The last line was shown for each CPU in the system.
    Testing v4.5 (where commit 790d849b was integrated) triggered
    similar messages. Same behaviour on a 2nd HP Proliant system.
    
    So commit 790d849b (cpufreq: pcc-cpufreq: update default value of
    cpuinfo_transition_latency) causes the system to use performance
    governor which, I guess, was not the intention of the patch.
    
    Enabling debug output in pcc-cpufreq provides following verbose output:
    
     pcc-cpufreq: (v1.10.00) driver loaded with frequency limits: 1200 MHz, 2800 MHz
     pcc_get_offset: for CPU 0: pcc_cpu_data input_offset: 0x44, pcc_cpu_data output_offset: 0x48
     init: policy->max is 2800000, policy->min is 1200000
     get: get_freq for CPU 0
     get: SUCCESS: (virtual) output_offset for cpu 0 is 0xffffc9000d7c0048, contains a value of: 0xff06. Speed is: 168000 MHz
     cpufreq: ondemand governor failed, too long transition latency of HW, fallback to performance governor
     target: CPU 0 should go to target freq: 2800000 (virtual) input_offset is 0xffffc9000d7c0044
     target: was SUCCESSFUL for cpu 0
    
    I am asking to revert 790d849b to re-enable usage of ondemand
    governor with pcc-cpufreq.
    
    Fixes: 790d849b (cpufreq: pcc-cpufreq: update default value of cpuinfo_transition_latency)
    CC: <stable@vger.kernel.org> # 4.5+
    Signed-off-by: default avatarAndreas Herrmann <aherrmann@suse.com>
    Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
    da7d3abe