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

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

Reviewed-by: Gautham R. Shenoy <gautham.shenoy@amd.com>
Link: https://lore.kernel.org/r/20260326193620.649441-1-mario.limonciello@amd.com
Signed-off-by: Mario Limonciello (AMD) <superm1@kernel.org>
(backported from commit 8cdc494)
[jamien: minor context-line drift in amd-pstate.c hunks from 3-way
auto-merge; +/- content is byte-identical to upstream.]
Signed-off-by: Jamie Nguyen <jamien@nvidia.com>

Author: superm1

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;
 
@@ -950,13 +948,15 @@ 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
 	 */
@@ -1019,9 +1019,7 @@ 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)
@@ -1088,14 +1086,9 @@ static void amd_pstate_cpu_exit(struct cpufreq_policy *policy)
 static ssize_t show_amd_pstate_max_freq(struct cpufreq_policy *policy,
 					char *buf)
 {
-	struct amd_cpudata *cpudata;
-	union perf_cached perf;
-
-	cpudata = policy->driver_data;
-	perf = READ_ONCE(cpudata->perf);
+	struct amd_cpudata *cpudata = policy->driver_data;
 
-	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,
@@ -1501,9 +1494,7 @@ 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);

drivers/cpufreq/amd-pstate.h

@@ -68,6 +68,7 @@ struct amd_aperf_mperf {
  * @min_limit_freq: Cached value of policy->min (in khz)
  * @max_limit_freq: Cached value of policy->max (in khz)
  * @nominal_freq: the frequency (in khz) that mapped to nominal_perf
+ * @max_freq: in ideal conditions the maximum frequency (in khz) possible frequency
  * @lowest_nonlinear_freq: the frequency (in khz) that mapped to lowest_nonlinear_perf
  * @cur: Difference of Aperf/Mperf/tsc count between last and current sample
  * @prev: Last Aperf/Mperf/tsc count value read from register
@@ -94,6 +95,7 @@ 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;