linux-kernel - Re: [PATCH v2 1/9] ARM: EXYNOS: cpuidle: fix AFTR mode check

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Date:	Fri, 20 Dec 2013 22:16:12 +0100
From:	Daniel Lezcano <daniel.lezcano@...aro.org>
To:	Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
	rjw@...ysocki.net
CC:	lenb@...nel.org, linux-pm@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-samsung-soc@...r.kernel.org,
	linuxppc-dev@...ts.ozlabs.org, kyungmin.park@...sung.com,
	Kukjin Kim <kgene.kim@...sung.com>
Subject: Re: [PATCH v2 1/9] ARM: EXYNOS: cpuidle: fix AFTR mode check

On 12/20/2013 07:47 PM, Bartlomiej Zolnierkiewicz wrote:
> The EXYNOS cpuidle driver code assumes that cpuidle core will handle
> dev->state_count smaller than drv->state_count but currently this is
> untrue (dev->state_count is used only for handling cpuidle state sysfs
> entries and drv->state_count is used for all other cases) and will not
> be fixed in the future as dev->state_count is planned to be removed.
>
> Fix the issue by checking for the max supported idle state in AFTR
> state's ->enter handler (exynos4_enter_lowpower()) and entering AFTR
> mode only when cores other than CPU0 are offline.
>
> Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>
> Signed-off-by: Kyungmin Park <kyungmin.park@...sung.com>
> Acked-by: Daniel Lezcano <daniel.lezcano@...aro.org>
> Cc: Kukjin Kim <kgene.kim@...sung.com>
> ---
>   arch/arm/mach-exynos/cpuidle.c | 8 ++------
>   1 file changed, 2 insertions(+), 6 deletions(-)
>
> diff --git a/arch/arm/mach-exynos/cpuidle.c b/arch/arm/mach-exynos/cpuidle.c
> index da65b03..f57cb91 100644
> --- a/arch/arm/mach-exynos/cpuidle.c
> +++ b/arch/arm/mach-exynos/cpuidle.c
> @@ -172,8 +172,8 @@ static int exynos4_enter_lowpower(struct cpuidle_device *dev,
>   {
>   	int new_index = index;
>
> -	/* This mode only can be entered when other core's are offline */
> -	if (num_online_cpus() > 1)
> +	/* AFTR can only be entered when cores other than CPU0 are offline */
> +	if (num_online_cpus() > 1 || dev->cpu != 0)
>   		new_index = drv->safe_state_index;
>
>   	if (new_index == 0)
> @@ -235,10 +235,6 @@ static int exynos_cpuidle_probe(struct platform_device *pdev)
>   		device = &per_cpu(exynos4_cpuidle_device, cpu_id);
>   		device->cpu = cpu_id;
>
> -		/* Support IDLE only */
> -		if (cpu_id != 0)
> -			device->state_count = 1;
> -
>   		ret = cpuidle_register_device(device);
>   		if (ret) {
>   			dev_err(&pdev->dev, "failed to register cpuidle device\n");
>

Hi Bartlomiej,

thanks for this cleanup. May be you can also add another patch to switch 
to the generic cpuidle_register function ?

Thanks
   -- Daniel

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