[PATCH] cpufreq/amd-pstate: Cache the max frequency in cpudata

[PATCH] cpufreq/amd-pstate: Cache the max frequency in cpudata

[Mario Limonciello]

The value of maximum frequency is fixed and never changes. Doing
calculations every time based off of perf is unnecessary.

Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
---
 drivers/cpufreq/amd-pstate.c | 21 ++++++++-------------
 drivers/cpufreq/amd-pstate.h |  1 +
 2 files changed, 9 insertions(+), 13 deletions(-)

diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
index 5aa9fcd80cf51..787aa3ba87b33 100644
--- a/drivers/cpufreq/amd-pstate.c
+++ b/drivers/cpufreq/amd-pstate.c
@@ -757,15 +757,13 @@ static void amd_pstate_adjust_perf(unsigned int cpu,
 static int amd_pstate_cpu_boost_update(struct cpufreq_policy *policy, bool on)
 {
 	struct amd_cpudata *cpudata = policy->driver_data;
-	union perf_cached perf = READ_ONCE(cpudata->perf);
-	u32 nominal_freq, max_freq;
+	u32 nominal_freq;
 	int ret = 0;
 
 	nominal_freq = READ_ONCE(cpudata->nominal_freq);
-	max_freq = perf_to_freq(perf, cpudata->nominal_freq, perf.highest_perf);
 
 	if (on)
-		policy->cpuinfo.max_freq = max_freq;
+		policy->cpuinfo.max_freq = cpudata->max_freq;
 	else if (policy->cpuinfo.max_freq > nominal_freq)
 		policy->cpuinfo.max_freq = nominal_freq;
 
@@ -952,13 +950,15 @@ static int amd_pstate_init_freq(struct amd_cpudata *cpudata)
 
 	WRITE_ONCE(cpudata->nominal_freq, nominal_freq);
 
+	/* max_freq is calculated according to (nominal_freq * highest_perf)/nominal_perf */
 	max_freq = perf_to_freq(perf, nominal_freq, perf.highest_perf);
+	WRITE_ONCE(cpudata->max_freq, max_freq);
+
 	lowest_nonlinear_freq = perf_to_freq(perf, nominal_freq, perf.lowest_nonlinear_perf);
 	WRITE_ONCE(cpudata->lowest_nonlinear_freq, lowest_nonlinear_freq);
 
 	/**
 	 * Below values need to be initialized correctly, otherwise driver will fail to load
-	 * max_freq is calculated according to (nominal_freq * highest_perf)/nominal_perf
 	 * lowest_nonlinear_freq is a value between [min_freq, nominal_freq]
 	 * Check _CPC in ACPI table objects if any values are incorrect
 	 */
@@ -1021,9 +1021,7 @@ static int amd_pstate_cpu_init(struct cpufreq_policy *policy)
 	policy->cpuinfo.min_freq = policy->min = perf_to_freq(perf,
 							      cpudata->nominal_freq,
 							      perf.lowest_perf);
-	policy->cpuinfo.max_freq = policy->max = perf_to_freq(perf,
-							      cpudata->nominal_freq,
-							      perf.highest_perf);
+	policy->cpuinfo.max_freq = policy->max = cpudata->max_freq;
 
 	ret = amd_pstate_cppc_enable(policy);
 	if (ret)
@@ -1096,8 +1094,7 @@ static ssize_t show_amd_pstate_max_freq(struct cpufreq_policy *policy,
 	cpudata = policy->driver_data;
 	perf = READ_ONCE(cpudata->perf);
 
-	return sysfs_emit(buf, "%u\n",
-			  perf_to_freq(perf, cpudata->nominal_freq, perf.highest_perf));
+	return sysfs_emit(buf, "%u\n", cpudata->max_freq);
 }
 
 static ssize_t show_amd_pstate_lowest_nonlinear_freq(struct cpufreq_policy *policy,
@@ -1503,9 +1500,7 @@ static int amd_pstate_epp_cpu_init(struct cpufreq_policy *policy)
 	policy->cpuinfo.min_freq = policy->min = perf_to_freq(perf,
 							      cpudata->nominal_freq,
 							      perf.lowest_perf);
-	policy->cpuinfo.max_freq = policy->max = perf_to_freq(perf,
-							      cpudata->nominal_freq,
-							      perf.highest_perf);
+	policy->cpuinfo.max_freq = policy->max = cpudata->max_freq;
 	policy->driver_data = cpudata;
 
 	ret = amd_pstate_cppc_enable(policy);
diff --git a/drivers/cpufreq/amd-pstate.h b/drivers/cpufreq/amd-pstate.h
index cb45fdca27a6c..485ee023d79c5 100644
--- a/drivers/cpufreq/amd-pstate.h
+++ b/drivers/cpufreq/amd-pstate.h
@@ -94,6 +94,7 @@ struct amd_cpudata {
 	u32	min_limit_freq;
 	u32	max_limit_freq;
 	u32	nominal_freq;
+	u32	max_freq;
 	u32	lowest_nonlinear_freq;
 
 	struct amd_aperf_mperf cur;
-- 
2.53.0

Re: [PATCH] cpufreq/amd-pstate: Cache the max frequency in cpudata

[kernel test robot]

Hi Mario,

kernel test robot noticed the following build warnings:

[auto build test WARNING on rafael-pm/linux-next]
[also build test WARNING on rafael-pm/bleeding-edge linus/master v6.16-rc1 next-20260313]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Mario-Limonciello/cpufreq-amd-pstate-Cache-the-max-frequency-in-cpudata/20260314-194005
base:   https://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm.git linux-next
patch link:    https://lore.kernel.org/r/20260312182442.3236386-1-mario.limonciello%40amd.com
patch subject: [PATCH] cpufreq/amd-pstate: Cache the max frequency in cpudata
config: x86_64-kexec (https://download.01.org/0day-ci/archive/20260314/202603141750.mDER1GM9-lkp@intel.com/config)
compiler: clang version 20.1.8 (https://github.com/llvm/llvm-project 87f0227cb60147a26a1eeb4fb06e3b505e9c7261)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260314/202603141750.mDER1GM9-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202603141750.mDER1GM9-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> drivers/cpufreq/amd-pstate.c:1092:20: warning: variable 'perf' set but not used [-Wunused-but-set-variable]
    1092 |         union perf_cached perf;
         |                           ^
   1 warning generated.


vim +/perf +1092 drivers/cpufreq/amd-pstate.c

ec4e3326a95507 Huang Rui         2021-12-24  1082  
ec4e3326a95507 Huang Rui         2021-12-24  1083  /*
ec4e3326a95507 Huang Rui         2021-12-24  1084   * This frequency is to indicate the maximum hardware frequency.
ec4e3326a95507 Huang Rui         2021-12-24  1085   * If boost is not active but supported, the frequency will be larger than the
ec4e3326a95507 Huang Rui         2021-12-24  1086   * one in cpuinfo.
ec4e3326a95507 Huang Rui         2021-12-24  1087   */
ec4e3326a95507 Huang Rui         2021-12-24  1088  static ssize_t show_amd_pstate_max_freq(struct cpufreq_policy *policy,
ec4e3326a95507 Huang Rui         2021-12-24  1089  					char *buf)
ec4e3326a95507 Huang Rui         2021-12-24  1090  {
009d1c29a45194 Mario Limonciello 2025-01-17  1091  	struct amd_cpudata *cpudata;
009d1c29a45194 Mario Limonciello 2025-01-17 @1092  	union perf_cached perf;
ec4e3326a95507 Huang Rui         2021-12-24  1093  
009d1c29a45194 Mario Limonciello 2025-01-17  1094  	cpudata = policy->driver_data;
009d1c29a45194 Mario Limonciello 2025-01-17  1095  	perf = READ_ONCE(cpudata->perf);
ec4e3326a95507 Huang Rui         2021-12-24  1096  
a6b5fc5470a623 Mario Limonciello 2026-03-12  1097  	return sysfs_emit(buf, "%u\n", cpudata->max_freq);
ec4e3326a95507 Huang Rui         2021-12-24  1098  }
ec4e3326a95507 Huang Rui         2021-12-24  1099  

-- 
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https://github.com/intel/lkp-tests/wiki