linux-kernel - Re: [PATCH V2] ARM: EXYNOS: cpu hotplug: use v7_exit_coherency

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Message-id: <5360AE05.7020106@samsung.com>
Date:	Wed, 30 Apr 2014 17:02:13 +0900
From:	Chanwoo Choi <cw00.choi@...sung.com>
To:	Leela Krishna Amudala <leela.krishna@...aro.org>
Cc:	linux-pm@...r.kernel.org, linux-samsung-soc@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	daniel.lezcano@...aro.org, nicolas.pitre@...aro.org,
	kgene.kim@...sung.com, amit.kucheria@...aro.org
Subject: Re: [PATCH V2] ARM: EXYNOS: cpu hotplug: use v7_exit_coherency_flush
 macro for cache disabling

Hi,

On 04/23/2014 02:52 PM, Leela Krishna Amudala wrote:
> A common macro v7_exit_coherency_flush available which does the below tasks in
> the seqeunce.
> -clearing C bit
> -clearing L1 cache
> -exit SMP
> -instruction and data synchronization
> 
> So removing the local functions which does the same thing and use the macro instead.
> 
> Signed-off-by: Leela Krishna Amudala <leela.krishna@...aro.org>
> Acked-by: Nicolas Pitre <nico@...aro.org>
> ---
> Changes since V1:
> 	- removed unwanted primary_part variable in exynos_cpu_die()
> 	- given more description in commit message
> 	  suggested by Daniel Lezcano <daniel.lezcano@...aro.org>
> 
>  arch/arm/mach-exynos/hotplug.c |   63 +---------------------------------------
>  1 file changed, 1 insertion(+), 62 deletions(-)
> 
> diff --git a/arch/arm/mach-exynos/hotplug.c b/arch/arm/mach-exynos/hotplug.c
> index 5eead53..9ca692d 100644
> --- a/arch/arm/mach-exynos/hotplug.c
> +++ b/arch/arm/mach-exynos/hotplug.c
> @@ -24,56 +24,6 @@
>  #include "common.h"
>  #include "regs-pmu.h"
>  
> -static inline void cpu_enter_lowpower_a9(void)
> -{
> -	unsigned int v;
> -
> -	asm volatile(
> -	"	mcr	p15, 0, %1, c7, c5, 0\n"
> -	"	mcr	p15, 0, %1, c7, c10, 4\n"
> -	/*
> -	 * Turn off coherency
> -	 */
> -	"	mrc	p15, 0, %0, c1, c0, 1\n"
> -	"	bic	%0, %0, %3\n"
> -	"	mcr	p15, 0, %0, c1, c0, 1\n"
> -	"	mrc	p15, 0, %0, c1, c0, 0\n"
> -	"	bic	%0, %0, %2\n"
> -	"	mcr	p15, 0, %0, c1, c0, 0\n"
> -	  : "=&r" (v)
> -	  : "r" (0), "Ir" (CR_C), "Ir" (0x40)
> -	  : "cc");
> -}
> -
> -static inline void cpu_enter_lowpower_a15(void)
> -{
> -	unsigned int v;
> -
> -	asm volatile(
> -	"	mrc	p15, 0, %0, c1, c0, 0\n"
> -	"	bic	%0, %0, %1\n"
> -	"	mcr	p15, 0, %0, c1, c0, 0\n"
> -	  : "=&r" (v)
> -	  : "Ir" (CR_C)
> -	  : "cc");
> -
> -	flush_cache_louis();
> -
> -	asm volatile(
> -	/*
> -	* Turn off coherency
> -	*/
> -	"	mrc	p15, 0, %0, c1, c0, 1\n"
> -	"	bic	%0, %0, %1\n"
> -	"	mcr	p15, 0, %0, c1, c0, 1\n"
> -	: "=&r" (v)
> -	: "Ir" (0x40)
> -	: "cc");
> -
> -	isb();
> -	dsb();
> -}
> -
>  static inline void cpu_leave_lowpower(void)
>  {
>  	unsigned int v;
> @@ -132,19 +82,8 @@ static inline void platform_do_lowpower(unsigned int cpu, int *spurious)
>  void __ref exynos_cpu_die(unsigned int cpu)
>  {
>  	int spurious = 0;
> -	int primary_part = 0;
>  
> -	/*
> -	 * we're ready for shutdown now, so do it.
> -	 * Exynos4 is A9 based while Exynos5 is A15; check the CPU part
> -	 * number by reading the Main ID register and then perform the
> -	 * appropriate sequence for entering low power.
> -	 */
> -	asm("mrc p15, 0, %0, c0, c0, 0" : "=r"(primary_part) : : "cc");
> -	if ((primary_part & 0xfff0) == 0xc0f0)
> -		cpu_enter_lowpower_a15();
> -	else
> -		cpu_enter_lowpower_a9();
> +	v7_exit_coherency_flush(louis);
>  
>  	platform_do_lowpower(cpu, &spurious);
>  
> 

I tested this patch on Exynos3250 based on Cortex-A7 dual core.

Tested-by: Chanwoo Choi <cw00.choi@...sung.com>

Thanks,
Chanwoo Choi

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