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

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Date:	Tue, 17 Mar 2015 16:18:37 +0100
From:	Daniel Lezcano <daniel.lezcano@...aro.org>
To:	Geert Uytterhoeven <geert@...ux-m68k.org>
CC:	Simon Horman <horms@...ge.net.au>,
	Magnus Damm <magnus.damm@...il.com>,
	Linux PM list <linux-pm@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	Linux-sh list <linux-sh@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] ARM: shmobile: cpuidle: Remove the pointless default
 driver

On 03/17/2015 04:06 PM, Geert Uytterhoeven wrote:
> Hi Daniel,
>
> On Tue, Mar 17, 2015 at 3:34 PM, Daniel Lezcano
> <daniel.lezcano@...aro.org> 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.
>
> Thanks for your patch!
>
>> [compiled only - no board - no test]
>>
>> Signed-off-by: Daniel Lezcano <daniel.lezcano@...aro.org>
>> ---
>>   arch/arm/mach-shmobile/common.h    |  3 ---
>>   arch/arm/mach-shmobile/cpuidle.c   | 37 -------------------------------------
>>   arch/arm/mach-shmobile/pm-sh7372.c |  2 +-
>>   3 files changed, 1 insertion(+), 41 deletions(-)
>>
>> diff --git a/arch/arm/mach-shmobile/common.h b/arch/arm/mach-shmobile/common.h
>> index 309025e..29b3088 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);
>> @@ -51,7 +49,6 @@ extern void __iomem *shmobile_scu_base;
>>   static inline void __init shmobile_init_late(void)
>>   {
>>          shmobile_suspend_init();
>> -       shmobile_cpuidle_init();
>
> Please remove the forward declaration and dummy for shmobile_cpuidle_init()
> above, too.

Ah, yeah. I thought I did it.

>>          shmobile_cpufreq_init();
>>   }
>>
>> diff --git a/arch/arm/mach-shmobile/cpuidle.c b/arch/arm/mach-shmobile/cpuidle.c
>> index 0afeb5c..e69de29 100644
>> --- a/arch/arm/mach-shmobile/cpuidle.c
>> +++ b/arch/arm/mach-shmobile/cpuidle.c
>> @@ -1,37 +0,0 @@
>
> If you remove this file, you should remove its entry from
> arch/arm/mach-shmobile/Makefile, too.
> (did you use a config with CONFIG_CPU_IDLE=n?).

Yeah, but I have an empty file still around, this is why it was not 
catched. Thanks for pointing this.

>> 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
>
> Support for sh7372 is scheduled for removal in v4.1, so this will become
> a no-op.

Cool. So everything will be self contained in this file then.

Thanks for the review.

   -- Daniel

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