linux-kernel - Re: [PATCH 1/2] cpuidle: fix finding state with min power

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Date:	Sat, 15 Dec 2012 01:02:15 +0100
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Sivaram Nair <sivaramn@...dia.com>
Cc:	rafael.j.wysocki@...el.com, len.brown@...el.com,
	daniel.lezcano@...aro.org, khilman@...com, ccross@...roid.com,
	riel@...hat.com, youquan.song@...el.com, akpm@...ux-foundation.org,
	shuox.liu@...el.com, linux-pm@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] cpuidle: fix finding state with min power_usage

On Friday, December 14, 2012 03:17:36 PM Sivaram Nair wrote:
> Since cpuidle_state.power_usage is a signed value, use INT_MAX (instead
> of -1) to init the local copies so that functions that tries to find
> cpuidle states with minimum power usage works correctly even if they use
> non-negative values.

I'm queuing this up for submission as v3.8 material.

Thanks,
Rafael


> Signed-off-by: Sivaram Nair <sivaramn@...dia.com>
> ---
>  drivers/cpuidle/cpuidle.c        |    2 +-
>  drivers/cpuidle/governors/menu.c |    2 +-
>  2 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c
> index 8df53dd..fb4a7dd 100644
> --- a/drivers/cpuidle/cpuidle.c
> +++ b/drivers/cpuidle/cpuidle.c
> @@ -70,7 +70,7 @@ int cpuidle_play_dead(void)
>  	struct cpuidle_device *dev = __this_cpu_read(cpuidle_devices);
>  	struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
>  	int i, dead_state = -1;
> -	int power_usage = -1;
> +	int power_usage = INT_MAX;
>  
>  	if (!drv)
>  		return -ENODEV;
> diff --git a/drivers/cpuidle/governors/menu.c b/drivers/cpuidle/governors/menu.c
> index bd40b94..20ea33a 100644
> --- a/drivers/cpuidle/governors/menu.c
> +++ b/drivers/cpuidle/governors/menu.c
> @@ -312,7 +312,7 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev)
>  {
>  	struct menu_device *data = &__get_cpu_var(menu_devices);
>  	int latency_req = pm_qos_request(PM_QOS_CPU_DMA_LATENCY);
> -	int power_usage = -1;
> +	int power_usage = INT_MAX;
>  	int i;
>  	int multiplier;
>  	struct timespec t;
> 
-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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