linux-kernel - Re: [PATCH 1/2] cpuidle: Drop disabled field from struct cpuidle

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Date:   Thu, 5 Dec 2019 12:15:05 +0100
From:   Daniel Lezcano <daniel.lezcano@...aro.org>
To:     "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Linux PM <linux-pm@...r.kernel.org>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
        Len Brown <len.brown@...el.com>, Len Brown <lenb@...nel.org>,
        Rafael Wysocki <rafael@...nel.org>,
        Yoshinori Sato <ysato@...rs.sourceforge.jp>,
        Rich Felker <dalias@...c.org>, linux-sh@...r.kernel.org
Subject: Re: [PATCH 1/2] cpuidle: Drop disabled field from struct
 cpuidle_state

On 21/11/2019 19:41, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> 
> After recent cpuidle updates the "disabled" field in struct
> cpuidle_state is only used by two drivers (intel_idle and shmobile
> cpuidle) for marking unusable idle states, but that may as well be
> achieved with the help of a state flag, so define an "unusable" idle
> state flag, CPUIDLE_FLAG_UNUSABLE, make the drivers in question use
> it instead of the "disabled" field and make the core set
> CPUIDLE_STATE_DISABLED_BY_DRIVER for the idle states with that flag
> set.
> 
> After the above changes, the "disabled" field in struct cpuidle_state
> is not used any more, so drop it.
> 
> No intentional functional impact.
> 
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> ---
> 
> Changes from RFC:
> 
>  - Do not add extra braces (unrelated to the rest of the patch).
> 
> ---
>  arch/sh/kernel/cpu/shmobile/cpuidle.c |    8 ++++----
>  drivers/cpuidle/cpuidle.c             |    2 +-
>  drivers/cpuidle/poll_state.c          |    1 -
>  drivers/idle/intel_idle.c             |    6 +++---
>  include/linux/cpuidle.h               |    2 +-
>  5 files changed, 9 insertions(+), 10 deletions(-)
> 
> Index: linux-pm/drivers/idle/intel_idle.c
> ===================================================================
> --- linux-pm.orig/drivers/idle/intel_idle.c
> +++ linux-pm/drivers/idle/intel_idle.c
> @@ -1291,8 +1291,8 @@ static void sklh_idle_state_table_update
>  			return;
>  	}
>  
> -	skl_cstates[5].disabled = 1;	/* C8-SKL */
> -	skl_cstates[6].disabled = 1;	/* C9-SKL */
> +	skl_cstates[5].flags |= CPUIDLE_FLAG_UNUSABLE;	/* C8-SKL */
> +	skl_cstates[6].flags |= CPUIDLE_FLAG_UNUSABLE;	/* C9-SKL */
>  }
>  /*
>   * intel_idle_state_table_update()
> @@ -1355,7 +1355,7 @@ static void __init intel_idle_cpuidle_dr
>  			continue;
>  
>  		/* if state marked as disabled, skip it */
> -		if (cpuidle_state_table[cstate].disabled != 0) {
> +		if (cpuidle_state_table[cstate].flags & CPUIDLE_FLAG_UNUSABLE) {
>  			pr_debug("state %s is disabled\n",
>  				 cpuidle_state_table[cstate].name);
>  			continue;
> Index: linux-pm/include/linux/cpuidle.h
> ===================================================================
> --- linux-pm.orig/include/linux/cpuidle.h
> +++ linux-pm/include/linux/cpuidle.h
> @@ -54,7 +54,6 @@ struct cpuidle_state {
>  	unsigned int	exit_latency; /* in US */
>  	int		power_usage; /* in mW */
>  	unsigned int	target_residency; /* in US */
> -	bool		disabled; /* disabled on all CPUs */
>  
>  	int (*enter)	(struct cpuidle_device *dev,
>  			struct cpuidle_driver *drv,
> @@ -77,6 +76,7 @@ struct cpuidle_state {
>  #define CPUIDLE_FLAG_POLLING	BIT(0) /* polling state */
>  #define CPUIDLE_FLAG_COUPLED	BIT(1) /* state applies to multiple cpus */
>  #define CPUIDLE_FLAG_TIMER_STOP BIT(2) /* timer is stopped on this state */
> +#define CPUIDLE_FLAG_UNUSABLE	BIT(3) /* avoid using this state */
>  
>  struct cpuidle_device_kobj;
>  struct cpuidle_state_kobj;
> Index: linux-pm/arch/sh/kernel/cpu/shmobile/cpuidle.c
> ===================================================================
> --- linux-pm.orig/arch/sh/kernel/cpu/shmobile/cpuidle.c
> +++ linux-pm/arch/sh/kernel/cpu/shmobile/cpuidle.c
> @@ -67,7 +67,7 @@ static struct cpuidle_driver cpuidle_dri
>  			.enter = cpuidle_sleep_enter,
>  			.name = "C2",
>  			.desc = "SuperH Sleep Mode [SF]",
> -			.disabled = true,
> +			.flags = CPUIDLE_FLAG_UNUSABLE,
>  		},
>  		{
>  			.exit_latency = 2300,
> @@ -76,7 +76,7 @@ static struct cpuidle_driver cpuidle_dri
>  			.enter = cpuidle_sleep_enter,
>  			.name = "C3",
>  			.desc = "SuperH Mobile Standby Mode [SF]",
> -			.disabled = true,
> +			.flags = CPUIDLE_FLAG_UNUSABLE,
>  		},
>  	},
>  	.safe_state_index = 0,
> @@ -86,10 +86,10 @@ static struct cpuidle_driver cpuidle_dri
>  int __init sh_mobile_setup_cpuidle(void)
>  {
>  	if (sh_mobile_sleep_supported & SUSP_SH_SF)
> -		cpuidle_driver.states[1].disabled = false;
> +		cpuidle_driver.states[1].flags = CPUIDLE_FLAG_NONE;

That will overwrite other flags value, bit operation should be used here
to remove CPUIDLE_FLAG_UNUSABLE.

>  	if (sh_mobile_sleep_supported & SUSP_SH_STANDBY)
> -		cpuidle_driver.states[2].disabled = false;
> +		cpuidle_driver.states[2].flags = CPUIDLE_FLAG_NONE;
>  
>  	return cpuidle_register(&cpuidle_driver, NULL);
>  }
> Index: linux-pm/drivers/cpuidle/cpuidle.c
> ===================================================================
> --- linux-pm.orig/drivers/cpuidle/cpuidle.c
> +++ linux-pm/drivers/cpuidle/cpuidle.c
> @@ -570,7 +570,7 @@ static int __cpuidle_register_device(str
>  		return -EINVAL;
>  
>  	for (i = 0; i < drv->state_count; i++)
> -		if (drv->states[i].disabled)
> +		if (drv->states[i].flags & CPUIDLE_FLAG_UNUSABLE)
>  			dev->states_usage[i].disable |= CPUIDLE_STATE_DISABLED_BY_DRIVER;
>  
>  	per_cpu(cpuidle_devices, dev->cpu) = dev;
> Index: linux-pm/drivers/cpuidle/poll_state.c
> ===================================================================
> --- linux-pm.orig/drivers/cpuidle/poll_state.c
> +++ linux-pm/drivers/cpuidle/poll_state.c
> @@ -53,7 +53,6 @@ void cpuidle_poll_state_init(struct cpui
>  	state->target_residency_ns = 0;
>  	state->power_usage = -1;
>  	state->enter = poll_idle;
> -	state->disabled = false;
>  	state->flags = CPUIDLE_FLAG_POLLING;
>  }
>  EXPORT_SYMBOL_GPL(cpuidle_poll_state_init);
> 
> 
> 


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