linux-kernel - Re: [PATCH 3/9] arm: add call to CPU idle quirks handler

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Date:	Thu, 25 Jun 2015 12:42:56 -0400 (EDT)
From:	Nicolas Pitre <nicolas.pitre@...aro.org>
To:	Arnd Bergmann <arnd@...db.de>
cc:	Paul Osmialowski <pawelo@...g.net.pl>,
	Andrew Morton <akpm@...ux-foundation.org>,
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Subject: Re: [PATCH 3/9] arm: add call to CPU idle quirks handler

On Tue, 23 Jun 2015, Arnd Bergmann wrote:

> On Tuesday 23 June 2015 23:19:41 Paul Osmialowski wrote:
> > Some SoCs need additional actions to be performed after arch idle,
> > e.g. Kinetis requires invalidation of the I/D bus cache.
> > 
> > Such handler could be held in provided <mach/idle.h> header file.
> > 
> > Signed-off-by: Paul Osmialowski <pawelo@...g.net.pl>
> > ---
> >  arch/arm/Kconfig          | 7 +++++++
> >  arch/arm/kernel/process.c | 7 +++++++
> >  2 files changed, 14 insertions(+)
> > 
> > diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
> > index 8e3a833..8ef8f8f 100644
> > --- a/arch/arm/Kconfig
> > +++ b/arch/arm/Kconfig
> > @@ -98,6 +98,13 @@ config ARM_HAS_SG_CHAIN
> >  config NEED_SG_DMA_LENGTH
> >  	bool
> >  
> > +config NEED_MACH_IDLE_H
> > +	bool
> > +
> > +config ARM_CPU_IDLE_QUIRKS
> > +	bool
> > +	select NEED_MACH_IDLE_H
> > +
> 
> We're not adding header files like this, please come up
> with another solution. How about a cpuidle driver, or
> possibly just overriding arm_pm_idle()?

If the WFI instruction always requires I and D flushing, then it might 
be a better idea to provide a replacement for the corresponding 
cpu_*_do_idle function.  Plenty of examples exist for other cpu_* 
functions.


Nicolas
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