linux-kernel - Re: [PATCH v5 3/5] powerpc/85xx: add sleep and deep sleep support

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Message-ID: <4FCE303D.9090801@freescale.com>
Date:	Tue, 5 Jun 2012 11:13:49 -0500
From:	Scott Wood <scottwood@...escale.com>
To:	Zhao Chenhui <chenhui.zhao@...escale.com>
CC:	<linuxppc-dev@...ts.ozlabs.org>, <linux-kernel@...r.kernel.org>,
	<galak@...nel.crashing.org>, <leoli@...escale.com>
Subject: Re: [PATCH v5 3/5] powerpc/85xx: add sleep and deep sleep support

On 06/05/2012 06:35 AM, Zhao Chenhui wrote:
> On Mon, Jun 04, 2012 at 05:58:38PM -0500, Scott Wood wrote:
>> On 06/04/2012 06:12 AM, Zhao Chenhui wrote:
>>> On Fri, Jun 01, 2012 at 04:54:35PM -0500, Scott Wood wrote:
>>>> On 05/11/2012 06:53 AM, Zhao Chenhui wrote:
>>>>> diff --git a/arch/powerpc/include/asm/cacheflush.h b/arch/powerpc/include/asm/cacheflush.h
>>>>> index 94ec20a..baa000c 100644
>>>>> --- a/arch/powerpc/include/asm/cacheflush.h
>>>>> +++ b/arch/powerpc/include/asm/cacheflush.h
>>>>> @@ -33,6 +33,11 @@ extern void flush_dcache_page(struct page *page);
>>>>>  #if defined(CONFIG_FSL_BOOKE) || defined(CONFIG_6xx)
>>>>>  extern void __flush_disable_L1(void);
>>>>>  #endif
>>>>> +#if defined(CONFIG_FSL_BOOKE)
>>>>> +extern void flush_dcache_L1(void);
>>>>> +#else
>>>>> +#define flush_dcache_L1()	do { } while (0)
>>>>> +#endif
>>>>
>>>> It doesn't seem right to no-op this on other platforms.
>>>
>>> The pmc_suspend_enter() in fsl_pmc.c used by mpc85xx and mpc86xx,
>>> but flush_dcache_L1() have no definition in mpc86xx platform.
>>> I will write flush_dcache_L1() for mpc86xx platform.
>>
>> How about only calling the function when it's needed?  If we didn't need
>> an L1 flush here on 86xx before, why do we need it now?
> 
> How about using CONFIG_PPC_85xx to gard it, like this.
> 
> 	case PM_SUSPEND_STANDBY:
> 		local_irq_disable();
> #ifdef CONFIG_PPC_85xx
> 		flush_dcache_L1();
> #endif
> 		setbits32(&pmc_regs->powmgtcsr, POWMGTCSR_SLP);

We don't support building 85xx/86xx in the same kernel and likely never
will, so this is OK.

>>>> Can we introduce a symbol that specifically means pre-e500mc e500,
>>>> rather than using negative logic?
>>>>
>>>> I think something like CONFIG_PPC_E500_V1_V2 has been proposed before.
>>>
>>> Agree. But CONFIG_PPC_E500_V1_V2 haven't been merged.
>>
>> Has the concept been NACKed, or just forgotten?  If the latter, you
>> could include it in this patchset.
>>
>> -Scott
> 
> In patchwork, it's state is "Superseded".
> http://patchwork.ozlabs.org/patch/124284/

I still think there's value in adding such a symbol.

-Scott

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