linux-kernel - Re: [PATCH v2 08/44] cpuidle,imx6: Push RCU-idle into driver

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Message-ID: <20220919142123.GE58444@lothringen>
Date:   Mon, 19 Sep 2022 16:21:23 +0200
From:   Frederic Weisbecker <frederic@...nel.org>
To:     Peter Zijlstra <peterz@...radead.org>
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Subject: Re: [PATCH v2 08/44] cpuidle,imx6: Push RCU-idle into driver

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.

Hmm, what ends up calling RCU_IDLE() here? Also what about
cpu_do_idle()?

Thanks.

> 
> Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.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,
>  			.name = "LOW-POWER-IDLE",
>  			.desc = "ARM power off",
> 
>