linux-kernel - [PATCH 1/2] acpi: processor: allow fixing up the frequency for a performance state

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Message-ID: <20221221155203.11347-2-ptyadav@amazon.de>
Date:   Wed, 21 Dec 2022 16:52:02 +0100
From:   Pratyush Yadav <ptyadav@...zon.de>
To:     <linux-pm@...r.kernel.org>
CC:     Pratyush Yadav <ptyadav@...zon.de>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Len Brown <lenb@...nel.org>,
        Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Robert Moore <robert.moore@...el.com>,
        <linux-acpi@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <devel@...ica.org>
Subject: [PATCH 1/2] acpi: processor: allow fixing up the frequency for a performance state

In some cases the ACPI table can have an incorrect frequency populated
for a performance state. For example, in Intel platforms, the Turbo
frequency is just listed as +1 MHz above the max non-turbo frequency.
The frequency can actually go much higher based on various factors like
temperature, voltage, etc.

Allow drivers like intel_pstate to fix up performance state frequencies
with the actual maximum value. While at it, also update the QoS
constraints if needed to match the new frequency values.

Signed-off-by: Pratyush Yadav <ptyadav@...zon.de>
---
 drivers/acpi/processor_perflib.c | 40 ++++++++++++++++++++++++++++++++
 include/acpi/processor.h         |  2 ++
 2 files changed, 42 insertions(+)

diff --git a/drivers/acpi/processor_perflib.c b/drivers/acpi/processor_perflib.c
index 970f04a958cd..4958aee4c024 100644
--- a/drivers/acpi/processor_perflib.c
+++ b/drivers/acpi/processor_perflib.c
@@ -766,3 +766,43 @@ void acpi_processor_unregister_performance(unsigned int cpu)
 	mutex_unlock(&performance_mutex);
 }
 EXPORT_SYMBOL(acpi_processor_unregister_performance);
+
+int acpi_processor_fixup_perf_state(unsigned int cpu, unsigned int state,
+				    unsigned int frequency)
+{
+	struct acpi_processor *pr;
+	int ret;
+
+	mutex_lock(&performance_mutex);
+
+	pr = per_cpu(processors, cpu);
+	if (!pr) {
+		mutex_unlock(&performance_mutex);
+		return -ENODEV;
+	}
+
+	if (!pr->performance) {
+		mutex_unlock(&performance_mutex);
+		return -EINVAL;
+	}
+
+	if (state >= pr->performance->state_count) {
+		mutex_unlock(&performance_mutex);
+		return -EINVAL;
+	}
+
+	pr->performance->states[state].core_frequency = frequency;
+
+	if (ignore_ppc != 1 && state == pr->performance_platform_limit &&
+	    freq_qos_request_active(&pr->perflib_req)) {
+		ret = freq_qos_update_request(&pr->perflib_req,
+					      frequency * 1000);
+		if (ret < 0)
+			pr_warn("Failed to update perflib freq constraint: CPU%d (%d)\n",
+				pr->id, ret);
+	}
+
+	mutex_unlock(&performance_mutex);
+	return 0;
+}
+EXPORT_SYMBOL(acpi_processor_fixup_perf_state);
diff --git a/include/acpi/processor.h b/include/acpi/processor.h
index 94181fe9780a..daff978cfa7d 100644
--- a/include/acpi/processor.h
+++ b/include/acpi/processor.h
@@ -258,6 +258,8 @@ extern int acpi_processor_preregister_performance(struct
 extern int acpi_processor_register_performance(struct acpi_processor_performance
 					       *performance, unsigned int cpu);
 extern void acpi_processor_unregister_performance(unsigned int cpu);
+extern int acpi_processor_fixup_perf_state(unsigned int cpu, unsigned int state,
+					   unsigned int frequency);
 
 int acpi_processor_pstate_control(void);
 /* note: this locks both the calling module and the processor module
-- 
2.38.1