linux-kernel - Re: [PATCH 1/2] PPC: powernv: remove redundant cpuidle_idle

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Message-ID: <alpine.LFD.2.11.1402070105170.1906@knanqh.ubzr>
Date:	Fri, 7 Feb 2014 01:17:57 +0000 (GMT)
From:	Nicolas Pitre <nicolas.pitre@...aro.org>
To:	Preeti U Murthy <preeti@...ux.vnet.ibm.com>
cc:	Daniel Lezcano <daniel.lezcano@...aro.org>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	LKML <linux-kernel@...r.kernel.org>,
	Linux ARM Kernel ML <linux-arm-kernel@...ts.infradead.org>,
	linuxppc-dev@...ts.ozlabs.org,
	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	Lists linaro-kernel <linaro-kernel@...ts.linaro.org>
Subject: Re: [PATCH 1/2] PPC: powernv: remove redundant cpuidle_idle_call()

On Thu, 6 Feb 2014, Preeti U Murthy wrote:

> Hi Daniel,
> 
> On 02/06/2014 09:55 PM, Daniel Lezcano wrote:
> > Hi Nico,
> > 
> > 
> > On 6 February 2014 14:16, Nicolas Pitre <nicolas.pitre@...aro.org> wrote:
> > 
> >> The core idle loop now takes care of it.
> >>
> >> Signed-off-by: Nicolas Pitre <nico@...aro.org>
> >> ---
> >>  arch/powerpc/platforms/powernv/setup.c | 13 +------------
> >>  1 file changed, 1 insertion(+), 12 deletions(-)
> >>
> >> diff --git a/arch/powerpc/platforms/powernv/setup.c
> >> b/arch/powerpc/platforms/powernv/setup.c
> >> index 21166f65c9..a932feb290 100644
> >> --- a/arch/powerpc/platforms/powernv/setup.c
> >> +++ b/arch/powerpc/platforms/powernv/setup.c
> >> @@ -26,7 +26,6 @@
> >>  #include <linux/of_fdt.h>
> >>  #include <linux/interrupt.h>
> >>  #include <linux/bug.h>
> >> -#include <linux/cpuidle.h>
> >>
> >>  #include <asm/machdep.h>
> >>  #include <asm/firmware.h>
> >> @@ -217,16 +216,6 @@ static int __init pnv_probe(void)
> >>         return 1;
> >>  }
> >>
> >> -void powernv_idle(void)
> >> -{
> >> -       /* Hook to cpuidle framework if available, else
> >> -        * call on default platform idle code
> >> -        */
> >> -       if (cpuidle_idle_call()) {
> >> -               power7_idle();
> >> -       }
> >>
> > 
> > The cpuidle_idle_call is called from arch_cpu_idle in
> > arch/powerpc/kernel/idle.c between a ppc64_runlatch_off|on section.
> > Shouldn't the cpuidle-powernv driver call these functions when entering
> > idle ?
> 
> Yes they should, I will send out a patch that does that ontop of this.
> There have been cpuidle driver cleanups for powernv and pseries in this
> merge window. While no change would be required in the pseries cpuidle
> driver as a result of Nicolas's cleanup, we would need to add the
> ppc64_runlatch_on and off functions before and after the entry into the
> powernv idle states.

What about creating arch_cpu_idle_enter() and arch_cpu_idle_exit() in 
arch/powerpc/kernel/idle.c and calling ppc64_runlatch_off() and 
ppc64_runlatch_on() respectively from there instead?  Would that work?  
That would make the idle consolidation much easier afterwards.


Nicolas
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