linux-kernel - Re: [PATCH 2/3] ARM: rockchip: ensure CPU to enter WIF state

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Date:	Fri, 05 Jun 2015 14:32:27 +0800
From:	Kever Yang <kever.yang@...k-chips.com>
To:	Caesar Wang <wxt@...k-chips.com>, Heiko Stuebner <heiko@...ech.de>
CC:	Russell King <linux@....linux.org.uk>,
	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	dianders@...omium.org, linux-kernel@...r.kernel.org,
	linux-rockchip@...ts.infradead.org,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 2/3] ARM: rockchip: ensure CPU to enter WIF state

Hi Caesar,

Subject typo WIF/WFI.

On 06/05/2015 12:47 PM, Caesar Wang wrote:
> In idle mode, core1/2/3 of Cortex-A17 should be either power off or in
> WFI/WFE state.
> we can delay 1ms to ensure the CPU enter WFI state.
>
> Signed-off-by: Caesar Wang <wxt@...k-chips.com>
> ---
>
>   arch/arm/mach-rockchip/platsmp.c | 3 +++
>   1 file changed, 3 insertions(+)
>
> diff --git a/arch/arm/mach-rockchip/platsmp.c b/arch/arm/mach-rockchip/platsmp.c
> index 1230d3d..978c357 100644
> --- a/arch/arm/mach-rockchip/platsmp.c
> +++ b/arch/arm/mach-rockchip/platsmp.c
> @@ -316,6 +316,9 @@ static void __init rockchip_smp_prepare_cpus(unsigned int max_cpus)
>   #ifdef CONFIG_HOTPLUG_CPU
>   static int rockchip_cpu_kill(unsigned int cpu)
>   {
> +	/* ensure CPU can enter the WFI/WFE state */
> +	mdelay(1);
> +
Does it matter if core is not in WFI state when we want to power down it?

Thanks,
- Kever
>   	pmu_set_power_domain(0 + cpu, false);
>   	return 1;
>   }

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