Hi,
On Sat, Nov 21, 2015 at 1:16 AM, Srinivas Pandruvada
<srinivas.pandruv...@linux.intel.com> wrote:
>
>
> On 11/18/2015 02:58 PM, Alexandra Yates wrote:
>>
>> When changing from powersave to performance governors
>> Intel_pstate fails to update the MSR values that reflect the
>> max_perf_pct to 100%. For instance in SKL reading rdmsr 0x774:
>>
>> Governor MSR max_perf_pct
>> ========= ======== ============
>> Powersave 80002808 100%
>> Powersave 80002008 80%
>> Performance 80002028 [error] 100%
>> Performance 80002828 [expected] 100%
>>
>> The line label [error] shows the culprit. At this point the MSR
>> should reflect the max_perf_pct that is 100%, that corresponds
>> to MSR 80002828 as shown on the next line of the example. Which
>> is the maximum performance for the Performance governor.
>> Instead it holds back the MSR value previously set by the
>> Powersave, in this case 80002028.
>>
>> This patch allows the system to print the correct MSR value
>> 80002828 that corresponds to the 100% max_perf_pct when changing
>> from powersave to performance governors.
Is this only about what is printed or does it mean that the driver
actually uses an incorrect MSR value?
>> For more information on the MSR values for SKL please visit
>> ISDM under Managing HWP.
>>
>> Signed-off-by: Alexandra Yates <alexandra.ya...@linux.intel.com>
>
> Acked-by: Srinivas Pandruvada <srinivas.pandruv...@linux.intel.com>
>>
>> ---
>> drivers/cpufreq/intel_pstate.c | 2 ++
>> 1 file changed, 2 insertions(+)
>>
>> diff --git a/drivers/cpufreq/intel_pstate.c
>> b/drivers/cpufreq/intel_pstate.c
>> index 2e31d09..0eeb7da 100644
>> --- a/drivers/cpufreq/intel_pstate.c
>> +++ b/drivers/cpufreq/intel_pstate.c
>> @@ -1242,6 +1242,8 @@ static int intel_pstate_set_policy(struct
>> cpufreq_policy *policy)
>> policy->max >= policy->cpuinfo.max_freq) {
>> pr_debug("intel_pstate: set performance\n");
>> limits = &performance_limits;
>> + if (hwp_active)
>> + intel_pstate_hwp_set();
Honestly, I'm not really sure how this is matching the changelog.
What it does is to ensure that the correct limits are used when in the
HWP mode too as far as I can say. Is my understanding correct here?
>> return 0;
>> }
>>
>>
> --
Thanks,
Rafael
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