x86/amd: Detect preferred cores in amd_get_boost_ratio_numerator()

AMD systems that support preferred cores will use "166" as their
numerator for max frequency calculations instead of "255".

Add a function for detecting preferred cores by looking at the
highest perf value on all cores.

If preferred cores are enabled return 166 and if disabled the
value in the highest perf register. As the function will be called
multiple times, cache the values for the boost numerator and if
preferred cores will be enabled in global variables.

Reviewed-by: Gautham R. Shenoy <gautham.shenoy@amd.com>
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>

1 files changed, 13 insertions, 21 deletions

diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
index 8da567913f63..937a3a817743 100644
--- a/drivers/cpufreq/amd-pstate.c
+++ b/drivers/cpufreq/amd-pstate.c
@@ -815,32 +815,18 @@ static DECLARE_WORK(sched_prefcore_work, amd_pstste_sched_prefcore_workfn);
 
 static void amd_pstate_init_prefcore(struct amd_cpudata *cpudata)
 {
-	int ret, prio;
-	u32 highest_perf;
-
-	ret = amd_get_highest_perf(cpudata->cpu, &highest_perf);
-	if (ret)
+	/* user disabled or not detected */
+	if (!amd_pstate_prefcore)
 		return;
 
 	cpudata->hw_prefcore = true;
-	/* check if CPPC preferred core feature is enabled*/
-	if (highest_perf < CPPC_MAX_PERF)
-		prio = (int)highest_perf;
-	else {
-		pr_debug("AMD CPPC preferred core is unsupported!\n");
-		cpudata->hw_prefcore = false;
-		return;
-	}
-
-	if (!amd_pstate_prefcore)
-		return;
 
 	/*
 	 * The priorities can be set regardless of whether or not
 	 * sched_set_itmt_support(true) has been called and it is valid to
 	 * update them at any time after it has been called.
 	 */
-	sched_set_itmt_core_prio(prio, cpudata->cpu);
+	sched_set_itmt_core_prio((int)READ_ONCE(cpudata->highest_perf), cpudata->cpu);
 
 	schedule_work(&sched_prefcore_work);
 }
@@ -1011,12 +997,12 @@ static int amd_pstate_cpu_init(struct cpufreq_policy *policy)
 
 	cpudata->cpu = policy->cpu;
 
-	amd_pstate_init_prefcore(cpudata);
-
 	ret = amd_pstate_init_perf(cpudata);
 	if (ret)
 		goto free_cpudata1;
 
+	amd_pstate_init_prefcore(cpudata);
+
 	ret = amd_pstate_init_freq(cpudata);
 	if (ret)
 		goto free_cpudata1;
@@ -1466,12 +1452,12 @@ static int amd_pstate_epp_cpu_init(struct cpufreq_policy *policy)
 	cpudata->cpu = policy->cpu;
 	cpudata->epp_policy = 0;
 
-	amd_pstate_init_prefcore(cpudata);
-
 	ret = amd_pstate_init_perf(cpudata);
 	if (ret)
 		goto free_cpudata1;
 
+	amd_pstate_init_prefcore(cpudata);
+
 	ret = amd_pstate_init_freq(cpudata);
 	if (ret)
 		goto free_cpudata1;
@@ -1916,6 +1902,12 @@ static int __init amd_pstate_init(void)
 		static_call_update(amd_pstate_update_perf, cppc_update_perf);
 	}
 
+	if (amd_pstate_prefcore) {
+		ret = amd_detect_prefcore(&amd_pstate_prefcore);
+		if (ret)
+			return ret;
+	}
+
 	/* enable amd pstate feature */
 	ret = amd_pstate_enable(true);
 	if (ret) {