linux-kernel - Re: [PATCH V2 7/8] ARM: cpuidle: Register per cpuidle device

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Message-ID: <20150319110806.GE24556@red-moon>
Date:	Thu, 19 Mar 2015 11:08:06 +0000
From:	Lorenzo Pieralisi <lorenzo.pieralisi@....com>
To:	Daniel Lezcano <daniel.lezcano@...aro.org>
Cc:	"rjw@...ysocki.net" <rjw@...ysocki.net>,
	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Catalin Marinas <Catalin.Marinas@....com>,
	"robherring2@...il.com" <robherring2@...il.com>,
	"arnd@...db.de" <arnd@...db.de>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"lina.iyer@...aro.org" <lina.iyer@...aro.org>
Subject: Re: [PATCH V2 7/8] ARM: cpuidle: Register per cpuidle device

On Wed, Mar 18, 2015 at 06:46:11PM +0000, Daniel Lezcano wrote:
> Some architectures have some cpus which does not support idle states.
> 
> Let the underlying low level code to return -ENOSYS when it is not
> possible to set an idle state.

http://www.spinics.net/lists/linux-acpi/msg55550.html

-ENXIO ?

> 
> Signed-off-by: Daniel Lezcano <daniel.lezcano@...aro.org>
> ---
>  drivers/cpuidle/cpuidle-arm.c | 45 +++++++++++++++++++++++++++++++++++++++++--
>  1 file changed, 43 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/cpuidle/cpuidle-arm.c b/drivers/cpuidle/cpuidle-arm.c
> index 1c94b88..0682ed0 100644
> --- a/drivers/cpuidle/cpuidle-arm.c
> +++ b/drivers/cpuidle/cpuidle-arm.c
> @@ -17,11 +17,14 @@
>  #include <linux/kernel.h>
>  #include <linux/module.h>
>  #include <linux/of.h>
> +#include <linux/slab.h>
>  
>  #include <asm/cpuidle.h>
>  
>  #include "dt_idle_states.h"
>  
> +static DEFINE_PER_CPU(struct cpuidle_device, *cpuidle_arm_dev);
> +
>  /*
>   * arm_enter_idle_state - Programs CPU to enter the specified state
>   *
> @@ -94,6 +97,7 @@ static int __init arm_idle_init(void)
>  {
>  	int cpu, ret;
>  	struct cpuidle_driver *drv = &arm_idle_driver;
> +	struct cpuidle_device *dev;
>  
>  	/*
>  	 * Initialize idle states data, starting at index 1.
> @@ -105,18 +109,55 @@ static int __init arm_idle_init(void)
>  	if (ret <= 0)
>  		return ret ? : -ENODEV;
>  
> +	ret = cpuidle_register_driver(drv);
> +	if (ret) {
> +		pr_err("Failed to register cpuidle driver\n");
> +		return ret;
> +	}
> +
>  	/*
>  	 * Call arch CPU operations in order to initialize
>  	 * idle states suspend back-end specific data
>  	 */
>  	for_each_possible_cpu(cpu) {
>  		ret = arm_cpuidle_init(cpu);
> +
> +		/* This cpu does not support any idle states */
> +		if (ret == -ENOSYS)
> +			continue;
> +
>  		if (ret) {
>  			pr_err("CPU %d failed to init idle CPU ops\n", cpu);
> -			return ret;
> +			goto out_fail;
> +		}
> +
> +		dev = kzalloc(sizeof(*dev), GFP_KERNEL);
> +		if (!dev) {
> +			pr_err("Failed to allocate cpuidle device\n");
> +			goto out_fail;
> +		}
> +
> +		dev->cpu = cpu;
> +		per_cpu(cpuidle_arm_dev, cpu) = dev;
> +
> +		ret = cpuidle_register_device(dev);
> +		if (ret) {
> +			pr_err("Failed to register cpuidle device for CPU %d\n",
> +			       cpu);
> +			kfree(dev);
> +			goto out_fail;
>  		}
>  	}
> +out:
> +	return ret;

return 0;

>  
> -	return cpuidle_register(drv, NULL);
> +out_fail:
> +	for (cpu--; cpu <= 0; cpu--) {

This loop is wrong.

> +		dev = per_cpu(cpuidle_arm_dev, cpu);
> +		cpuidle_unregister_device(dev);
> +		kfree(dev);
> +	}
> +	cpuidle_unregister_driver(drv);
> +	goto out;

You just:

return ret;

little point in jumping around to just return.

Lorenzo
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