linux-kernel - Re: [PATCH V2] ARM: shmobile: cpuidle: Remove the pointless default driver

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Message-ID: <550847BA.8050503@linaro.org>
Date:	Tue, 17 Mar 2015 16:26:50 +0100
From:	Daniel Lezcano <daniel.lezcano@...aro.org>
To:	geert Uytterhoeven <geert@...ux-m68k.org>
CC:	horms@...ge.net.au, magnus.damm@...il.com,
	linux-pm@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	linux-sh@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH V2] ARM: shmobile: cpuidle: Remove the pointless default
 driver


Sorry Geert, I forget to Cc you.

On 03/17/2015 04:25 PM, Daniel Lezcano wrote:
> The default idle driver uses one state with the WFI instruction.
> The default idle routine invokes WFI when no cpuidle driver is present.
>
> The default cpuidle driver is pointless and does not give more than the
> default idle routine and moreover it pulls all the mathematics tied with
> the cpuidle governor for nothing, hence consuming more energy.
>
> Remove the default driver, the related code and register the driver directly.
>
> [compiled only - no board - no test]
>
> Signed-off-by: Daniel Lezcano <daniel.lezcano@...aro.org>
> ---
>   arch/arm/mach-shmobile/Makefile    |  1 -
>   arch/arm/mach-shmobile/common.h    |  9 ---------
>   arch/arm/mach-shmobile/cpuidle.c   | 37 -------------------------------------
>   arch/arm/mach-shmobile/pm-sh7372.c |  2 +-
>   4 files changed, 1 insertion(+), 48 deletions(-)
>   delete mode 100644 arch/arm/mach-shmobile/cpuidle.c
>
> diff --git a/arch/arm/mach-shmobile/Makefile b/arch/arm/mach-shmobile/Makefile
> index d53996e..c604296 100644
> --- a/arch/arm/mach-shmobile/Makefile
> +++ b/arch/arm/mach-shmobile/Makefile
> @@ -46,7 +46,6 @@ smp-$(CONFIG_ARCH_EMEV2)	+= smp-emev2.o headsmp-scu.o platsmp-scu.o
>
>   # PM objects
>   obj-$(CONFIG_SUSPEND)		+= suspend.o
> -obj-$(CONFIG_CPU_IDLE)		+= cpuidle.o
>   obj-$(CONFIG_CPU_FREQ)		+= cpufreq.o
>   obj-$(CONFIG_PM_RCAR)		+= pm-rcar.o
>   obj-$(CONFIG_PM_RMOBILE)	+= pm-rmobile.o
> diff --git a/arch/arm/mach-shmobile/common.h b/arch/arm/mach-shmobile/common.h
> index 309025e..1dc0971 100644
> --- a/arch/arm/mach-shmobile/common.h
> +++ b/arch/arm/mach-shmobile/common.h
> @@ -23,8 +23,6 @@ struct clk;
>   extern int shmobile_clk_init(void);
>   extern void shmobile_handle_irq_intc(struct pt_regs *);
>   extern struct platform_suspend_ops shmobile_suspend_ops;
> -struct cpuidle_driver;
> -extern void shmobile_cpuidle_set_driver(struct cpuidle_driver *drv);
>
>   #ifdef CONFIG_SUSPEND
>   int shmobile_suspend_init(void);
> @@ -34,12 +32,6 @@ static inline int shmobile_suspend_init(void) { return 0; }
>   static inline void shmobile_smp_apmu_suspend_init(void) { }
>   #endif
>
> -#ifdef CONFIG_CPU_IDLE
> -int shmobile_cpuidle_init(void);
> -#else
> -static inline int shmobile_cpuidle_init(void) { return 0; }
> -#endif
> -
>   #ifdef CONFIG_CPU_FREQ
>   int shmobile_cpufreq_init(void);
>   #else
> @@ -51,7 +43,6 @@ extern void __iomem *shmobile_scu_base;
>   static inline void __init shmobile_init_late(void)
>   {
>   	shmobile_suspend_init();
> -	shmobile_cpuidle_init();
>   	shmobile_cpufreq_init();
>   }
>
> diff --git a/arch/arm/mach-shmobile/cpuidle.c b/arch/arm/mach-shmobile/cpuidle.c
> deleted file mode 100644
> index 0afeb5c..0000000
> --- a/arch/arm/mach-shmobile/cpuidle.c
> +++ /dev/null
> @@ -1,37 +0,0 @@
> -/*
> - * CPUIdle support code for SH-Mobile ARM
> - *
> - *  Copyright (C) 2011 Magnus Damm
> - *
> - * This file is subject to the terms and conditions of the GNU General Public
> - * License.  See the file "COPYING" in the main directory of this archive
> - * for more details.
> - */
> -
> -#include <linux/pm.h>
> -#include <linux/cpuidle.h>
> -#include <linux/suspend.h>
> -#include <linux/module.h>
> -#include <linux/err.h>
> -#include <asm/cpuidle.h>
> -#include <asm/io.h>
> -
> -static struct cpuidle_driver shmobile_cpuidle_default_driver = {
> -	.name			= "shmobile_cpuidle",
> -	.owner			= THIS_MODULE,
> -	.states[0]		= ARM_CPUIDLE_WFI_STATE,
> -	.safe_state_index	= 0, /* C1 */
> -	.state_count		= 1,
> -};
> -
> -static struct cpuidle_driver *cpuidle_drv = &shmobile_cpuidle_default_driver;
> -
> -void __init shmobile_cpuidle_set_driver(struct cpuidle_driver *drv)
> -{
> -	cpuidle_drv = drv;
> -}
> -
> -int __init shmobile_cpuidle_init(void)
> -{
> -	return cpuidle_register(cpuidle_drv, NULL);
> -}
> diff --git a/arch/arm/mach-shmobile/pm-sh7372.c b/arch/arm/mach-shmobile/pm-sh7372.c
> index c0293ae..9f19052 100644
> --- a/arch/arm/mach-shmobile/pm-sh7372.c
> +++ b/arch/arm/mach-shmobile/pm-sh7372.c
> @@ -462,7 +462,7 @@ static struct cpuidle_driver sh7372_cpuidle_driver = {
>
>   static void __init sh7372_cpuidle_init(void)
>   {
> -	shmobile_cpuidle_set_driver(&sh7372_cpuidle_driver);
> +	return cpuidle_register(cpuidle_drv, NULL);
>   }
>   #else
>   static void __init sh7372_cpuidle_init(void) {}
>


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