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

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Message-ID: <73b77acd-813a-458b-61e2-87116720cc38@mailbox.org>
Date:   Tue, 20 Dec 2022 18:13:41 +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 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:

---
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