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Date:   Mon, 19 Sep 2022 17:03:04 +0200
From:   Peter Zijlstra <peterz@infradead.org>
To:     Frederic Weisbecker <frederic@kernel.org>
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Subject: Re: [PATCH v2 08/44] cpuidle,imx6: Push RCU-idle into driver
Message-ID: <YyiEqDSJVOZrQYg8@hirez.programming.kicks-ass.net>
References: <20220919095939.761690562@infradead.org>
 <20220919101520.869531945@infradead.org>
 <20220919144941.GA62211@lothringen>
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In-Reply-To: <20220919144941.GA62211@lothringen>
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On Mon, Sep 19, 2022 at 04:49:41PM +0200, Frederic Weisbecker wrote:
> On Mon, Sep 19, 2022 at 11:59:47AM +0200, Peter Zijlstra wrote:
> > Doing RCU-idle outside the driver, only to then temporarily enable it
> > again, at least twice, before going idle is daft.
> > 
> > Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
> > ---
> >  arch/arm/mach-imx/cpuidle-imx6sx.c |    5 ++++-
> >  1 file changed, 4 insertions(+), 1 deletion(-)
> > 
> > --- a/arch/arm/mach-imx/cpuidle-imx6sx.c
> > +++ b/arch/arm/mach-imx/cpuidle-imx6sx.c
> > @@ -47,7 +47,9 @@ static int imx6sx_enter_wait(struct cpui
> >  		cpu_pm_enter();
> >  		cpu_cluster_pm_enter();
> >  
> > +		ct_idle_enter();
> >  		cpu_suspend(0, imx6sx_idle_finish);
> > +		ct_idle_exit();
> >  
> >  		cpu_cluster_pm_exit();
> >  		cpu_pm_exit();
> > @@ -87,7 +89,8 @@ static struct cpuidle_driver imx6sx_cpui
> >  			 */
> >  			.exit_latency = 300,
> >  			.target_residency = 500,
> > -			.flags = CPUIDLE_FLAG_TIMER_STOP,
> > +			.flags = CPUIDLE_FLAG_TIMER_STOP |
> > +				 CPUIDLE_FLAG_RCU_IDLE,
> >  			.enter = imx6sx_enter_wait,
> 
> There is a second one below that also uses imx6sx_enter_wait.

Oh, above you mean; but only @index==2 gets us into the whole PM crud.
@index==1 is fine afaict.