linux-kernel - [PATCH v2 2/4] cppc_cpufreq: clarify support for coordination types

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Date:   Mon, 14 Dec 2020 12:38:21 +0000
From:   Ionela Voinescu <ionela.voinescu@....com>
To:     rjw@...ysocki.net, viresh.kumar@...aro.org, lenb@...nel.org
Cc:     yousaf.kaukab@...e.com, jeremy.linton@....com, lukasz.luba@....com,
        valentin.schneider@....com, linux-acpi@...r.kernel.org,
        linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
        ionela.voinescu@....com
Subject: [PATCH v2 2/4] cppc_cpufreq: clarify support for coordination types

The previous coordination type handling in the cppc_cpufreq init code
created some confusion: the comment mentioned "Support only SW_ANY for
now" while only the SW_ALL/ALL case resulted in a failure. The other
coordination types (HW_ALL/HW, NONE) were silently supported.

Clarify support for coordination types while describing in comments the
intended behavior.

Signed-off-by: Ionela Voinescu <ionela.voinescu@....com>
Acked-by: Viresh Kumar <viresh.kumar@...aro.org>
Cc: Rafael J. Wysocki <rjw@...ysocki.net>
Cc: Viresh Kumar <viresh.kumar@...aro.org>
---
 drivers/cpufreq/cppc_cpufreq.c | 19 ++++++++++++-------
 1 file changed, 12 insertions(+), 7 deletions(-)

diff --git a/drivers/cpufreq/cppc_cpufreq.c b/drivers/cpufreq/cppc_cpufreq.c
index 2700fc71d4e8..f15a44c8b6b7 100644
--- a/drivers/cpufreq/cppc_cpufreq.c
+++ b/drivers/cpufreq/cppc_cpufreq.c
@@ -244,7 +244,7 @@ static int cppc_cpufreq_cpu_init(struct cpufreq_policy *policy)
 	struct cppc_cpudata *cpu_data = all_cpu_data[policy->cpu];
 	struct cppc_perf_caps *caps = &cpu_data->perf_caps;
 	unsigned int cpu = policy->cpu;
-	int ret = 0;
+	int i, ret = 0;
 
 	cpu_data->cpu = cpu;
 	ret = cppc_get_perf_caps(cpu, caps);
@@ -281,9 +281,13 @@ static int cppc_cpufreq_cpu_init(struct cpufreq_policy *policy)
 	policy->transition_delay_us = cppc_cpufreq_get_transition_delay_us(cpu);
 	policy->shared_type = cpu_data->shared_type;
 
-	if (policy->shared_type == CPUFREQ_SHARED_TYPE_ANY) {
-		int i;
-
+	switch (policy->shared_type) {
+	case CPUFREQ_SHARED_TYPE_HW:
+	case CPUFREQ_SHARED_TYPE_NONE:
+		/* Nothing to be done - we'll have a policy for each CPU */
+		break;
+	case CPUFREQ_SHARED_TYPE_ANY:
+		 /* All CPUs in the domain will share a policy */
 		cpumask_copy(policy->cpus, cpu_data->shared_cpu_map);
 
 		for_each_cpu(i, policy->cpus) {
@@ -293,9 +297,10 @@ static int cppc_cpufreq_cpu_init(struct cpufreq_policy *policy)
 			memcpy(&all_cpu_data[i]->perf_caps, caps,
 			       sizeof(cpu_data->perf_caps));
 		}
-	} else if (policy->shared_type == CPUFREQ_SHARED_TYPE_ALL) {
-		/* Support only SW_ANY for now. */
-		pr_debug("Unsupported CPU co-ord type\n");
+		break;
+	default:
+		pr_debug("Unsupported CPU co-ord type: %d\n",
+			 policy->shared_type);
 		return -EFAULT;
 	}
 
-- 
2.29.2.dirty