linux-kernel - [PATCH 3.12 034/124] cpufreq: pcc: Enable autoload of pcc-cpufreq for ACPI processors

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Message-Id: <17459111ac04d613d0ab464d68c10b9f8899e9ce.1438076484.git.jslaby@suse.cz>
Date:	Tue, 28 Jul 2015 11:42:48 +0200
From:	Jiri Slaby <jslaby@...e.cz>
To:	stable@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org,
	Lenny Szubowicz <lszubowi@...hat.com>,
	Joseph Szczypek <joseph.szczypek@...com>,
	"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
	Jiri Slaby <jslaby@...e.cz>
Subject: [PATCH 3.12 034/124] cpufreq: pcc: Enable autoload of pcc-cpufreq for ACPI processors

From: Lenny Szubowicz <lszubowi@...hat.com>

3.12-stable review patch.  If anyone has any objections, please let me know.

===============

commit 7e7e8fe69820c6fa31395dbbd8e348e3c69cd2a9 upstream.

The pcc-cpufreq driver is not automatically loaded on systems where
the platform's power management setting requires this driver.
Instead, on those systems no CPU frequency driver is registered and
active.

Make the autoloading matching criteria for loading the pcc-cpufreq
driver the same as done in acpi-cpufreq by commit c655affbd524d01
("ACPI / cpufreq: Add ACPI processor device IDs to acpi-cpufreq").

x86 CPU frequency drivers are now typically autoloaded by specifying
MODULE_DEVICE_TABLE entries and x86cpu model specific matching.
But pcc-cpufreq was omitted when acpi-cpufreq and other drivers were
changed to use this approach.

Both acpi-cpufreq and pcc-cpufreq depend on a distinct and mutually
exclusive set of ACPI methods which are not directly tied to specific
processor model numbers. Both of these drivers have init routines
which look for their required ACPI methods. As a result, only the
appropriate driver registers as the cpu frequency driver and the other
one ends up being unloaded.

Tested on various systems where acpi-cpufreq, intel_pstate, and
pcc-cpufreq are the expected cpu frequency drivers.

Signed-off-by: Lenny Szubowicz <lszubowi@...hat.com>
Signed-off-by: Joseph Szczypek <joseph.szczypek@...com>
Reported-by: Trinh Dao <trinh.dao@...com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
Signed-off-by: Jiri Slaby <jslaby@...e.cz>
---
 drivers/cpufreq/pcc-cpufreq.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/cpufreq/pcc-cpufreq.c b/drivers/cpufreq/pcc-cpufreq.c
index d81c4e5ea0ad..99c85231e270 100644
--- a/drivers/cpufreq/pcc-cpufreq.c
+++ b/drivers/cpufreq/pcc-cpufreq.c
@@ -616,6 +616,13 @@ static void __exit pcc_cpufreq_exit(void)
 	free_percpu(pcc_cpu_info);
 }

+static const struct acpi_device_id processor_device_ids[] = {
+	{ACPI_PROCESSOR_OBJECT_HID, },
+	{ACPI_PROCESSOR_DEVICE_HID, },
+	{},
+};
+MODULE_DEVICE_TABLE(acpi, processor_device_ids);
+
 MODULE_AUTHOR("Matthew Garrett, Naga Chumbalkar");
 MODULE_VERSION(PCC_VERSION);
 MODULE_DESCRIPTION("Processor Clocking Control interface driver");
-- 
2.4.6

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