linux-kernel - Re: [PATCH v8 00/13] Implement AMD Pstate EPP Driver

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Message-ID: <7602a0c7-df8c-5d6d-401d-55620d28c584@mailbox.org>
Date:   Tue, 20 Dec 2022 18:52:32 +0000
From:   Tor Vic <torvic9@...lbox.org>
To:     Perry Yuan <perry.yuan@....com>, rafael.j.wysocki@...el.com,
        Mario.Limonciello@....com, ray.huang@....com,
        viresh.kumar@...aro.org
Cc:     Deepak.Sharma@....com, Nathan.Fontenot@....com,
        Alexander.Deucher@....com, Shimmer.Huang@....com,
        Xiaojian.Du@....com, Li.Meng@....com, wyes.karny@....com,
        linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v8 00/13] Implement AMD Pstate EPP Driver


On 20.12.22 18:13, Tor Vic wrote:
> 
> On 19.12.22 06:40, Perry Yuan wrote:
>> Hi all,
>>
>> This patchset implements one new AMD CPU frequency driver
>> `amd-pstate-epp` instance for better performance and power control.
>> CPPC has a parameter called energy preference performance (EPP).
>> The EPP is used in the CCLK DPM controller to drive the frequency that 
>> a core
>> is going to operate during short periods of activity.
>> EPP values will be utilized for different OS profiles (balanced, 
>> performance, power savings).
>>
> 
> Using v8 and clang-15 on 6.1 I get:
> 

Got it.
Mario was right. INTEL_PSTATE must be selected, it has become a dependency.

That doesn't seem correct.

With it selected, it builds just fine. Not tested though.

> ---
> ld.lld: error: undefined symbol: energy_perf_strings
>  >>> referenced by amd-pstate.c:789 
> (/tmp/makepkg/linux61-vd/src/linux-stable/drivers/cpufreq/amd-pstate.c:789)
>  >>>               vmlinux.o:(show_energy_performance_preference)
>  >>> referenced by amd-pstate.c:768 
> (/tmp/makepkg/linux61-vd/src/linux-stable/drivers/cpufreq/amd-pstate.c:768)
>  >>>               vmlinux.o:(store_energy_performance_preference)
>  >>> referenced by amd-pstate.c:749 
> (/tmp/makepkg/linux61-vd/src/linux-stable/drivers/cpufreq/amd-pstate.c:749)
>  >>>               
> vmlinux.o:(show_energy_performance_available_preferences)
>  >>> referenced 1 more times
>  >>> did you mean: energy_perf_strings
>  >>> defined in: vmlinux.o
> 
> ld.lld: error: undefined symbol: epp_values
>  >>> referenced by amd-pstate.c:189 
> (/tmp/makepkg/linux61-vd/src/linux-stable/drivers/cpufreq/amd-pstate.c:189)
>  >>>               vmlinux.o:(store_energy_performance_preference)
> ---
> 
> and a few warnings:
> 
> ---
> drivers/cpufreq/amd-pstate.c:966:6: warning: variable 'ret' is used 
> uninitialized whenever 'if' condition is true [-Wsometimes-uninitialized]
>          if (rc)
>              ^~
> drivers/cpufreq/amd-pstate.c:1025:9: note: uninitialized use occurs here
>          return ret;
>                 ^~~
> drivers/cpufreq/amd-pstate.c:966:2: note: remove the 'if' if its 
> condition is always false
>          if (rc)
>          ^~~~~~~
> drivers/cpufreq/amd-pstate.c:962:6: warning: variable 'ret' is used 
> uninitialized whenever 'if' condition is true [-Wsometimes-uninitialized]
>          if (!dev)
>              ^~~~
> drivers/cpufreq/amd-pstate.c:1025:9: note: uninitialized use occurs here
>          return ret;
>                 ^~~
> drivers/cpufreq/amd-pstate.c:962:2: note: remove the 'if' if its 
> condition is always false
>          if (!dev)
>          ^~~~~~~~~
> drivers/cpufreq/amd-pstate.c:949:66: note: initialize the variable 'ret' 
> to silence this warning
>          int min_freq, max_freq, nominal_freq, lowest_nonlinear_freq, ret;
>                                                                          ^
> 
>   = 0
> drivers/cpufreq/amd-pstate.c:996:52: warning: variable 'value' is 
> uninitialized when used here [-Wuninitialized]
>          cpudata->epp_cached = amd_pstate_get_epp(cpudata, value);
>                                                            ^~~~~
> drivers/cpufreq/amd-pstate.c:953:11: note: initialize the variable 
> 'value' to silence this warning
>          u64 value;
>                   ^
>                    = 0
> drivers/cpufreq/amd-pstate.c:1085:6: warning: variable 'epp' is used 
> uninitialized whenever 'if' condition is true [-Wsometimes-uninitialized]
>          if (cpudata->epp_policy == cpudata->policy)
>              ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> drivers/cpufreq/amd-pstate.c:1110:30: note: uninitialized use occurs here
>          amd_pstate_set_epp(cpudata, epp);
>                                      ^~~
> drivers/cpufreq/amd-pstate.c:1085:2: note: remove the 'if' if its 
> condition is always false
>          if (cpudata->epp_policy == cpudata->policy)
>          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> drivers/cpufreq/amd-pstate.c:1064:9: note: initialize the variable 'epp' 
> to silence this warning
>          s16 epp;
>                 ^
>                  = 0
> ---
> 
> Cheers,
> 
> Tor Vic
>