linux-kernel - [PATCH v3] ARM: tegra: cpuidle: implement cpuidle_state.enter

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Message-Id: <1432046953-12945-1-git-send-email-tomeu.vizoso@collabora.com>
Date:	Tue, 19 May 2015 16:49:12 +0200
From:	Tomeu Vizoso <tomeu.vizoso@...labora.com>
To:	linux-pm@...r.kernel.org
Cc:	Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
	Tomeu Vizoso <tomeu.vizoso@...labora.com>,
	"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
	Russell King <linux@....linux.org.uk>,
	Stephen Warren <swarren@...dotorg.org>,
	Thierry Reding <thierry.reding@...il.com>,
	Alexandre Courbot <gnurou@...il.com>,
	Kukjin Kim <kgene.kim@...sung.com>,
	Ingo Molnar <mingo@...nel.org>,
	Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
	Daniel Lezcano <daniel.lezcano@...aro.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	linux-arm-kernel@...ts.infradead.org, linux-tegra@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH v3] ARM: tegra: cpuidle: implement cpuidle_state.enter_freeze()

This callback is expected to do the same as enter() but it has to
guarantee that interrupts aren't enabled at any point in its execution,
as the tick is frozen.

It will be called when the system goes to suspend-to-idle and will
reduce power usage because CPUs won't be awaken for unnecessary IRQs.

By setting the CPUIDLE_FLAG_TIMER_STOP flag, we can reuse the same code
for both the enter() and enter_freeze() callbacks.

Signed-off-by: Tomeu Vizoso <tomeu.vizoso@...labora.com>
Cc: Rafael J. Wysocki <rafael.j.wysocki@...el.com>

---

v3:	* Set CPUIDLE_FLAG_TIMER_STOP to simplify things as suggested by
	Lorenzo Pieralisi
v2:	* Disable FIQs also when suspending-to-idle
---
 arch/arm/mach-tegra/cpuidle-tegra114.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/arch/arm/mach-tegra/cpuidle-tegra114.c b/arch/arm/mach-tegra/cpuidle-tegra114.c
index 155807f..7e59ac0 100644
--- a/arch/arm/mach-tegra/cpuidle-tegra114.c
+++ b/arch/arm/mach-tegra/cpuidle-tegra114.c
@@ -44,16 +44,12 @@ static int tegra114_idle_power_down(struct cpuidle_device *dev,
 	tegra_set_cpu_in_lp2();
 	cpu_pm_enter();
 
-	tick_broadcast_enter();
-
 	call_firmware_op(prepare_idle);
 
 	/* Do suspend by ourselves if the firmware does not implement it */
 	if (call_firmware_op(do_idle, 0) == -ENOSYS)
 		cpu_suspend(0, tegra30_sleep_cpu_secondary_finish);
 
-	tick_broadcast_exit();
-
 	cpu_pm_exit();
 	tegra_clear_cpu_in_lp2();
 
@@ -61,6 +57,13 @@ static int tegra114_idle_power_down(struct cpuidle_device *dev,
 
 	return index;
 }
+
+static void tegra114_idle_enter_freeze(struct cpuidle_device *dev,
+				       struct cpuidle_driver *drv,
+				       int index)
+{
+       tegra114_idle_power_down(dev, drv, index);
+}
 #endif
 
 static struct cpuidle_driver tegra_idle_driver = {
@@ -72,8 +75,10 @@ static struct cpuidle_driver tegra_idle_driver = {
 #ifdef CONFIG_PM_SLEEP
 		[1] = {
 			.enter			= tegra114_idle_power_down,
+			.enter_freeze		= tegra114_idle_enter_freeze,
 			.exit_latency		= 500,
 			.target_residency	= 1000,
+			.flags			= CPUIDLE_FLAG_TIMER_STOP,
 			.power_usage		= 0,
 			.name			= "powered-down",
 			.desc			= "CPU power gated",
-- 
2.4.1

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