linux-kernel - Re: [PATCH 1/3] pm: at91: pm_suspend: add the WFI instruction support for ARMv7

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Message-ID: <20150217102255.GB11529@piout.net>
Date:	Tue, 17 Feb 2015 11:22:55 +0100
From:	Alexandre Belloni <alexandre.belloni@...e-electrons.com>
To:	Wenyou Yang <wenyou.yang@...el.com>
Cc:	nicolas.ferre@...el.com, linux@...im.org.za,
	linux@....linux.org.uk, linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org, sylvain.rochet@...secur.com,
	patrice.vilchez@...el.com, sergei.shtylyov@...entembedded.com,
	mark.rutland@....com, lorenzo.pieralisi@....com
Subject: Re: [PATCH 1/3] pm: at91: pm_suspend: add the WFI instruction
 support for ARMv7

On 12/02/2015 at 10:51:26 +0800, Wenyou Yang wrote :
> Add the WFI instruction to make the cpu to the idle state.
> In the meanwhile, disable the processor's clock.
> 
> Signed-off-by: Wenyou Yang <wenyou.yang@...el.com>
Acked-by: Alexandre Belloni <alexandre.belloni@...e-electrons.com>

> ---
>  arch/arm/mach-at91/pm_suspend.S |   20 +++++++++++++++++++-
>  1 file changed, 19 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/arm/mach-at91/pm_suspend.S b/arch/arm/mach-at91/pm_suspend.S
> index bebe3de..1c7256a 100644
> --- a/arch/arm/mach-at91/pm_suspend.S
> +++ b/arch/arm/mach-at91/pm_suspend.S
> @@ -51,6 +51,24 @@ tmp2	.req	r5
>  	beq	1b
>  	.endm
>  
> +/*
> + * Put the processor to enter the idle state
> + */
> +	.macro at91_cpu_idle
> +
> +#if defined(CONFIG_CPU_V7)
> +	mov	tmp1, #AT91_PMC_PCK
> +	str	tmp1, [pmc, #AT91_PMC_SCDR]
> +
> +	dsb
> +
> +	wfi		@ Wait For Interrupt
> +#else
> +	mcr	p15, 0, tmp1, c7, c0, 4
> +#endif
> +
> +	.endm
> +
>  	.text
>  
>  /*
> @@ -120,7 +138,7 @@ skip_disable_main_clock:
>  	ldr	pmc, .pmc_base
>  
>  	/* Wait for interrupt */
> -	mcr	p15, 0, tmp1, c7, c0, 4
> +	at91_cpu_idle
>  
>  	ldr	r0, .pm_mode
>  	tst	r0, #AT91_PM_SLOW_CLOCK
> -- 
> 1.7.9.5
> 

-- 
Alexandre Belloni, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com
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