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From: will.deacon@arm.com (Will Deacon)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 2/3] ARM: smp_scu: enable SCU standby support
Date: Mon, 21 Jul 2014 09:51:50 +0100	[thread overview]
Message-ID: <20140721085150.GB15666@arm.com> (raw)
In-Reply-To: <1405928755-19413-3-git-send-email-shawn.guo@freescale.com>

On Mon, Jul 21, 2014 at 08:45:54AM +0100, Shawn Guo wrote:
> With SCU standby enabled, SCU CLK will be turned off when all processors
> are in WFI mode.  And the clock will be turned on when any processor
> leaves WFI mode.
> 
> This behavior should be preferable in terms of power efficiency of
> system idle.  So let's set the SCU standby bit to enable the support in
> function scu_enable().
> 
> Signed-off-by: Shawn Guo <shawn.guo@freescale.com>
> ---
>  arch/arm/kernel/smp_scu.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/arm/kernel/smp_scu.c b/arch/arm/kernel/smp_scu.c
> index c947508f84e6..9f29d167d02c 100644
> --- a/arch/arm/kernel/smp_scu.c
> +++ b/arch/arm/kernel/smp_scu.c
> @@ -18,6 +18,7 @@
>  
>  #define SCU_CTRL		0x00
>  #define SCU_ENABLE		(1 << 0)
> +#define SCU_STANDBY_ENABLE	(1 << 5)
>  #define SCU_CONFIG		0x04
>  #define SCU_CPU_STATUS		0x08
>  #define SCU_INVALIDATE		0x0c
> @@ -54,7 +55,7 @@ void scu_enable(void __iomem *scu_base)
>  	if (scu_ctrl & SCU_ENABLE)
>  		return;
>  
> -	scu_ctrl |= SCU_ENABLE;
> +	scu_ctrl |= SCU_ENABLE | SCU_STANDBY_ENABLE;

I don't think this bit exists on all revisions of the A9.

Will

  reply	other threads:[~2014-07-21  8:51 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-07-21  7:45 [PATCH 0/3] Enable SCU standby support at core level Shawn Guo
2014-07-21  7:45 ` [PATCH 1/3] ARM: smp_scu: use macro for SCU enable bit Shawn Guo
2014-07-21  7:45 ` [PATCH 2/3] ARM: smp_scu: enable SCU standby support Shawn Guo
2014-07-21  8:51   ` Will Deacon [this message]
2014-07-21  9:27     ` Shawn Guo
2014-07-21  9:44       ` Will Deacon
2014-07-22  1:56         ` Shawn Guo
2014-07-21 10:26       ` Catalin Marinas
2014-07-22  2:09         ` Shawn Guo
2014-07-22 16:13           ` Catalin Marinas
2014-07-23  4:50             ` Shawn Guo
2014-07-23 16:45               ` Catalin Marinas
2014-07-24  8:49                 ` Shawn Guo
2014-07-21  7:45 ` [PATCH 3/3] ARM: imx: remove SCU standby enable code Shawn Guo

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