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

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Message-ID: <20150520090455.GC29274@red-moon>
Date:	Wed, 20 May 2015 10:04:55 +0100
From:	Lorenzo Pieralisi <lorenzo.pieralisi@....com>
To:	Tomeu Vizoso <tomeu.vizoso@...labora.com>
Cc:	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	"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-arm-kernel@...ts.infradead.org>,
	"linux-tegra@...r.kernel.org" <linux-tegra@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3] ARM: tegra: cpuidle: implement
 cpuidle_state.enter_freeze()

On Wed, May 20, 2015 at 09:55:41AM +0100, Tomeu Vizoso wrote:
> On 05/20/2015 10:44 AM, Lorenzo Pieralisi wrote:
> > On Tue, May 19, 2015 at 03:49:12PM +0100, Tomeu Vizoso wrote:
> >> 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);
> >> +}
> > 
> > You do not need this function, remove it and update the enter_freeze
> > pointer below with tegra114_idle_power_down please.
> 
> How so? The callbacks have different signatures.

Sorry, glossed over it, never mind.

Lorenzo
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