[PATCH v3 1/4] cpufreq: intel_pstate: Fix setting minimum P-state at init time

[Rafael J. Wysocki]

From: "Rafael J. Wysocki" <rafael.j.wysocki@xxxxxxxxx>

If HWP is enabled, writes to MSR_IA32_PERF_CTL have no effect,
so intel_pstate_get_cpu_pstates() should not attempt to call
intel_pstate_set_min_pstate() to set the minimum P-state for the
given CPU in that case.

Accordingly, remove the intel_pstate_set_min_pstate()
call from intel_pstate_get_cpu_pstates() and make both
intel_pstate_cpu_init() and intel_cpufreq_cpu_init() call
that function in their non-HWP code paths.

The HWP code path in intel_pstate_cpu_init() does not need to update
the current P-state of the CPU directly at all because it is taken
care of the processor automatically, but the HWP code path of
intel_cpufreq_cpu_init() should update it in principle to
initialize the DESIRED_PERF field in MSR_HWP_REQUEST.  For this
purpose, make it call intel_cpufreq_hwp_update() and pass
the minimum P-state limit to it as the current target value along
with the current minimum and maximum limits.

Fixes: f6ebbcf08f37 ("cpufreq: intel_pstate: Implement passive mode with HWP enabled")
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
---
 drivers/cpufreq/intel_pstate.c | 19 +++++++++++--------
 1 file changed, 11 insertions(+), 8 deletions(-)

diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
index 1f093e346430..95e41e975c45 100644
--- a/drivers/cpufreq/intel_pstate.c
+++ b/drivers/cpufreq/intel_pstate.c
@@ -2354,8 +2354,6 @@ static void intel_pstate_get_cpu_pstates(struct cpudata *cpu)
 
 	if (pstate_funcs.get_vid)
 		pstate_funcs.get_vid(cpu);
-
-	intel_pstate_set_min_pstate(cpu);
 }
 
 /*
@@ -3062,6 +3060,7 @@ static int __intel_pstate_cpu_init(struct cpufreq_policy *policy)
 static int intel_pstate_cpu_init(struct cpufreq_policy *policy)
 {
 	int ret = __intel_pstate_cpu_init(policy);
+	struct cpudata *cpu;
 
 	if (ret)
 		return ret;
@@ -3072,11 +3071,11 @@ static int intel_pstate_cpu_init(struct cpufreq_policy *policy)
 	 */
 	policy->policy = CPUFREQ_POLICY_POWERSAVE;
 
-	if (hwp_active) {
-		struct cpudata *cpu = all_cpu_data[policy->cpu];
-
+	cpu = all_cpu_data[policy->cpu];
+	if (hwp_active)
 		cpu->epp_cached = intel_pstate_get_epp(cpu, 0);
-	}
+	else
+		intel_pstate_set_min_pstate(cpu);
 
 	return 0;
 }
@@ -3300,8 +3299,6 @@ static int intel_cpufreq_cpu_init(struct cpufreq_policy *policy)
 		return ret;
 
 	policy->cpuinfo.transition_latency = INTEL_CPUFREQ_TRANSITION_LATENCY;
-	/* This reflects the intel_pstate_get_cpu_pstates() setting. */
-	policy->cur = policy->cpuinfo.min_freq;
 
 	req = kzalloc_objs(*req, 2);
 	if (!req) {
@@ -3322,9 +3319,15 @@ static int intel_cpufreq_cpu_init(struct cpufreq_policy *policy)
 		WRITE_ONCE(cpu->hwp_req_cached, value);
 
 		cpu->epp_cached = intel_pstate_get_epp(cpu, value);
+
+		intel_cpufreq_hwp_update(cpu, cpu->pstate.min_pstate,
+					 cpu->pstate.max_pstate,
+					 cpu->pstate.min_pstate, false);
 	} else {
 		policy->transition_delay_us = INTEL_CPUFREQ_TRANSITION_DELAY;
+		intel_pstate_set_min_pstate(cpu);
 	}
+	policy->cur = policy->cpuinfo.min_freq;
 
 	freq = DIV_ROUND_UP(cpu->pstate.turbo_freq * global.min_perf_pct, 100);
 
-- 
2.51.0