Re: [PATCH V2 3/3] ARM: tegra114: cpuidle: add powered-down state

[Daniel Lezcano <daniel.lezcano-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>]

On 06/04/2013 12:48 PM, Joseph Lo wrote:
> This supports CPU core power down on each CPU when CPU idle. When CPU go
> into this state, it saves it's context and needs a proper configuration
> in flow controller to power gate the CPU when CPU runs into WFI
> instruction. And the CPU also needs to set the IRQ as CPU power down idle
> wake up event in flow controller.
> 
> Signed-off-by: Joseph Lo <josephl-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>

I would like to understand why there is a WARN with the
CPUIDLE_FLAG_TIMER_STOP flag set before queuing this patch and ensure it
is not the tree hiding the forest.

Thanks
  -- Daniel

> ---
> V2:
> * remove some redundant code of memory barrier
> * remove the function declaration by rearranging the coding sequence 
> ---
>  arch/arm/mach-tegra/cpuidle-tegra114.c | 51 +++++++++++++++++++++++++++++++++-
>  1 file changed, 50 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/arm/mach-tegra/cpuidle-tegra114.c b/arch/arm/mach-tegra/cpuidle-tegra114.c
> index 1d1c602..e0b8730 100644
> --- a/arch/arm/mach-tegra/cpuidle-tegra114.c
> +++ b/arch/arm/mach-tegra/cpuidle-tegra114.c
> @@ -17,15 +17,64 @@
>  #include <linux/kernel.h>
>  #include <linux/module.h>
>  #include <linux/cpuidle.h>
> +#include <linux/cpu_pm.h>
> +#include <linux/clockchips.h>
>  
>  #include <asm/cpuidle.h>
> +#include <asm/suspend.h>
> +#include <asm/smp_plat.h>
> +
> +#include "pm.h"
> +#include "sleep.h"
> +
> +#ifdef CONFIG_PM_SLEEP
> +#define TEGRA114_MAX_STATES 2
> +#else
> +#define TEGRA114_MAX_STATES 1
> +#endif
> +
> +#ifdef CONFIG_PM_SLEEP
> +static int tegra114_idle_power_down(struct cpuidle_device *dev,
> +				    struct cpuidle_driver *drv,
> +				    int index)
> +{
> +	local_fiq_disable();
> +
> +	tegra_set_cpu_in_lp2();
> +	cpu_pm_enter();
> +
> +	clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER, &dev->cpu);
> +
> +	cpu_suspend(0, tegra30_sleep_cpu_secondary_finish);
> +
> +	clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_EXIT, &dev->cpu);
> +
> +	cpu_pm_exit();
> +	tegra_clear_cpu_in_lp2();
> +
> +	local_fiq_enable();
> +
> +	return index;
> +}
> +#endif
>  
>  static struct cpuidle_driver tegra_idle_driver = {
>  	.name = "tegra_idle",
>  	.owner = THIS_MODULE,
> -	.state_count = 1,
> +	.state_count = TEGRA114_MAX_STATES,
>  	.states = {
>  		[0] = ARM_CPUIDLE_WFI_STATE_PWR(600),
> +#ifdef CONFIG_PM_SLEEP
> +		[1] = {
> +			.enter			= tegra114_idle_power_down,
> +			.exit_latency		= 500,
> +			.target_residency	= 1000,
> +			.power_usage		= 0,
> +			.flags			= CPUIDLE_FLAG_TIME_VALID,
> +			.name			= "powered-down",
> +			.desc			= "CPU power gated",
> +		},
> +#endif
>  	},
>  };
>  
> 


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