[PATCH v3] cpufreq/amd-pstate: Cache the max frequency in cpudata

[Mario Limonciello]

From: "Mario Limonciello (AMD)" <superm1@xxxxxxxxxx>

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 (AMD) <superm1@xxxxxxxxxx>
---
v3:
 * rebase on Gautham's CPPC perf priority series
 * add kdoc
---
 drivers/cpufreq/amd-pstate.c | 27 +++++++++------------------
 drivers/cpufreq/amd-pstate.h |  2 ++
 2 files changed, 11 insertions(+), 18 deletions(-)

diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
index ed9fd4155a256..f207252eb5f5f 100644
--- a/drivers/cpufreq/amd-pstate.c
+++ b/drivers/cpufreq/amd-pstate.c
@@ -826,15 +826,13 @@ 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;
 
@@ -1021,13 +1019,15 @@ 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
 	 */
@@ -1090,9 +1090,7 @@ 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;
 
 	policy->driver_data = cpudata;
 	ret = amd_pstate_cppc_enable(policy);
@@ -1167,14 +1165,9 @@ 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,
@@ -1702,9 +1695,7 @@ 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 faead0b19a8a4..32b8b26ce388f 100644
--- a/drivers/cpufreq/amd-pstate.h
+++ b/drivers/cpufreq/amd-pstate.h
@@ -73,6 +73,7 @@ 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
  * @floor_freq: Cached value of the user requested floor_freq
  * @cur: Difference of Aperf/Mperf/tsc count between last and current sample
@@ -103,6 +104,7 @@ struct amd_cpudata {
 	u32	min_limit_freq;
 	u32	max_limit_freq;
 	u32	nominal_freq;
+	u32	max_freq;
 	u32	lowest_nonlinear_freq;
 	u32	floor_freq;
 
-- 
2.53.0