Fix spam error message when setting energy_performance_preference (#680)

* Fix spam error message when setting energy_performance_preference

The 'intel_pstate' driver does not allow the EPP to be set to anything
but 'performance' when the scaling governor is set to 'performance',
previously auto-cpufreq when the scaling-governor was set to
'performance' tried to set the EPP to 'balance-performance'
which caused a spam of write error messages in journalctl in system
with 'intel_pstate' drivers.
This is an intended behavior, since according to the [kernel documentation](https://docs.kernel.org/admin-guide/pm/intel_pstate.html#hwp-performance)
when HWP is enabled[(which is enabled by default during boot with supported processors)](https://docs.kernel.org/admin-guide/pm/intel_pstate.html#active-mode-with-hwp)
and scaling governor is set to performance the processor’s internal
P-state selection logic is expected to focus entirely on performance.
And this will override the EPP setting and reject any value different from 0 (“performance”).
This commit just changes the 'balance-performance' EPP preference in
set_performance() to 'performance'. Which fixes the spam issue.

* Only applies the spam error message fix for intel_pstate drivers

* Comparing the content of the file

intel_pstate/staus to make sure the condition only applies when "active"

* Override custom config EPP to "performance" for intel_pstate driver

auto_cpufreq/core.py

@@ -928,10 +928,22 @@ def set_performance():
         if dynboost_enabled:
             print('Not setting EPP (dynamic boosting is enabled)')
         else:
+            intel_pstate_status_path = "/sys/devices/system/cpu/intel_pstate/status"
+
             if conf.has_option("charger", "energy_performance_preference"):
                 epp = conf["charger"]["energy_performance_preference"]
+
+                if Path(intel_pstate_status_path).exists() and open(intel_pstate_status_path, 'r').read().strip() == "active" and epp != "performance":
+                    print(f'Warning "{epp}" EPP is not allowed in Intel CPU')
+                    print('Overriding EPP to "performance"')
+                    epp = "performance"
+
                 run(f"cpufreqctl.auto-cpufreq --epp --set={epp}", shell=True)
                 print(f'Setting to use: "{epp}" EPP')
+            else:
+                if Path(intel_pstate_status_path).exists() and open(intel_pstate_status_path, 'r').read().strip() == "active":
+                    run("cpufreqctl.auto-cpufreq --epp --set=performance", shell=True)
+                    print('Setting to use: "performance" EPP')
                 else:
                     run("cpufreqctl.auto-cpufreq --epp --set=balance_performance", shell=True)
                     print('Setting to use: "balance_performance" EPP')
@@ -1373,4 +1385,3 @@ def not_running_daemon_check():
     elif os.getenv("PKG_MARKER") == "SNAP" and dcheck == "disabled":
         daemon_not_running_msg()
         exit(1)
-