linux-kernel - Re: [PATCH 1/3] ACPI / idle: Move idle_boot

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Message-ID: <52D91CE2.3050704@arm.com>
Date:	Fri, 17 Jan 2014 12:06:58 +0000
From:	Sudeep Holla <Sudeep.Holla@....com>
To:	Hanjun Guo <hanjun.guo@...aro.org>
CC:	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Catalin Marinas <Catalin.Marinas@....com>,
	Will Deacon <Will.Deacon@....com>,
	Russell King - ARM Linux <linux@....linux.org.uk>,
	Daniel Lezcano <daniel.lezcano@...aro.org>,
	Sudeep.Holla@....com,
	"linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"grant.likely@...aro.org" <grant.likely@...aro.org>,
	Matthew Garrett <mjg59@...f.ucam.org>,
	Olof Johansson <olof@...om.net>,
	Linus Walleij <linus.walleij@...aro.org>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	"rob.herring@...xeda.com" <rob.herring@...xeda.com>,
	Mark Rutland <Mark.Rutland@....com>,
	Jon Masters <jonathan@...masters.org>,
	"patches@...aro.org" <patches@...aro.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linaro-kernel@...ts.linaro.org" <linaro-kernel@...ts.linaro.org>,
	"linaro-acpi@...ts.linaro.org" <linaro-acpi@...ts.linaro.org>
Subject: Re: [PATCH 1/3] ACPI / idle: Move idle_boot_override out of the arch
 directory

On 17/01/14 02:03, Hanjun Guo wrote:
> Move idle_boot_override out of the arch directory to be a single enum
> including both platforms values, this will make it rather easier to
> avoid ifdefs around which definitions are for which processor in
> generally used ACPI code.
> 
> IDLE_FORCE_MWAIT for IA64 is not used anywhere, so romove it.
> 
> No functional change in this patch.
> 
> Suggested-by: Alan <gnomes@...rguk.ukuu.org.uk>
> Signed-off-by: Hanjun Guo <hanjun.guo@...aro.org>
> ---
>  arch/ia64/include/asm/processor.h    | 3 ---
>  arch/powerpc/include/asm/processor.h | 1 -
>  arch/x86/include/asm/processor.h     | 3 ---
>  arch/x86/kernel/process.c            | 1 +
>  include/linux/cpu.h                  | 8 ++++++++
>  5 files changed, 9 insertions(+), 7 deletions(-)
> 
> diff --git a/arch/ia64/include/asm/processor.h b/arch/ia64/include/asm/processor.h
> index 5a84b3a..ccd63a0 100644
> --- a/arch/ia64/include/asm/processor.h
> +++ b/arch/ia64/include/asm/processor.h
> @@ -698,9 +698,6 @@ prefetchw (const void *x)
>  
>  extern unsigned long boot_option_idle_override;
>  
> -enum idle_boot_override {IDLE_NO_OVERRIDE=0, IDLE_HALT, IDLE_FORCE_MWAIT,
> -			 IDLE_NOMWAIT, IDLE_POLL};
> -
>  void default_idle(void);
>  
>  #define ia64_platform_is(x) (strcmp(x, ia64_platform_name) == 0)
> diff --git a/arch/powerpc/include/asm/processor.h b/arch/powerpc/include/asm/processor.h
> index fc14a38..06689c0 100644
> --- a/arch/powerpc/include/asm/processor.h
> +++ b/arch/powerpc/include/asm/processor.h
> @@ -440,7 +440,6 @@ static inline unsigned long get_clean_sp(unsigned long sp, int is_32)
>  #endif
>  
>  extern unsigned long cpuidle_disable;
> -enum idle_boot_override {IDLE_NO_OVERRIDE = 0, IDLE_POWERSAVE_OFF};
>  

I don't think it is used in the context of ACPI. Though it's same variable name,
it looks like it just used as boot to override the cpuidle option.
Does it still make any sense to combine this ?

>  extern int powersave_nap;	/* set if nap mode can be used in idle loop */
>  extern void power7_nap(void);
> diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
> index 7b034a4..4bee51a 100644
> --- a/arch/x86/include/asm/processor.h
> +++ b/arch/x86/include/asm/processor.h
> @@ -729,9 +729,6 @@ extern void init_amd_e400_c1e_mask(void);
>  extern unsigned long		boot_option_idle_override;
>  extern bool			amd_e400_c1e_detected;
>  
> -enum idle_boot_override {IDLE_NO_OVERRIDE=0, IDLE_HALT, IDLE_NOMWAIT,
> -			 IDLE_POLL};
> -
>  extern void enable_sep_cpu(void);
>  extern int sysenter_setup(void);
>  
> diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
> index 3fb8d95..62764ff 100644
> --- a/arch/x86/kernel/process.c
> +++ b/arch/x86/kernel/process.c
> @@ -17,6 +17,7 @@
>  #include <linux/stackprotector.h>
>  #include <linux/tick.h>
>  #include <linux/cpuidle.h>
> +#include <linux/cpu.h>
>  #include <trace/events/power.h>
>  #include <linux/hw_breakpoint.h>
>  #include <asm/cpu.h>
> diff --git a/include/linux/cpu.h b/include/linux/cpu.h
> index 03e235ad..e324561 100644
> --- a/include/linux/cpu.h
> +++ b/include/linux/cpu.h
> @@ -220,6 +220,14 @@ void cpu_idle(void);
>  
>  void cpu_idle_poll_ctrl(bool enable);
>  
> +enum idle_boot_override {
> +	IDLE_NO_OVERRIDE = 0,
> +	IDLE_HALT,
> +	IDLE_NOMWAIT,
> +	IDLE_POLL,
> +	IDLE_POWERSAVE_OFF
> +};
> +

I do understand the idea behind this change, but IMO HALT and MWAIT are x86
specific and may not make sense for other architectures.

It will also require every architecture using ACPI to export
boot_option_idle_override which may not be really required.

Further the only users of boot_option_idle_override(outside x86) are:

1. drivers/acpi/processor_core.c
   Your second patch is moving this to x86 specific code anyway

2. drivers/acpi/processor_idle.c
   Currently idle driver is bit x86 specific and needs modifications to get it
   working on ARM

Regards,
Sudeep

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