linux-kernel - Re: [PATCH 4/4][update] hwmon / exynos4_tmu: Use struct dev_pm

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Date:	Sun, 8 Jul 2012 13:30:04 -0700
From:	Guenter Roeck <linux@...ck-us.net>
To:	"Rafael J. Wysocki" <rjw@...k.pl>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Linux PM list <linux-pm@...r.kernel.org>,
	Hans de Goede <hdegoede@...hat.com>,
	Alistair John Strachan <alistair@...zero.co.uk>,
	lm-sensors@...sensors.org, Jean Delvare <khali@...ux-fr.org>,
	Kukjin Kim <kgene.kim@...sung.com>
Subject: Re: [PATCH 4/4][update] hwmon / exynos4_tmu: Use struct dev_pm_ops
 for power management

On Sun, Jul 08, 2012 at 09:48:15PM +0200, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rjw@...k.pl>
> 
Hi Rafael,

> Make the Exynos4 TMU driver define its PM callbacks through
> a struct dev_pm_ops object rather than by using legacy PM hooks
> in struct platform_driver.
> 
> Signed-off-by: Rafael J. Wysocki <rjw@...k.pl>
> ---
>  drivers/hwmon/exynos4_tmu.c |   18 +++++++++++-------
>  1 file changed, 11 insertions(+), 7 deletions(-)
> 
> Index: linux/drivers/hwmon/exynos4_tmu.c
> ===================================================================
> --- linux.orig/drivers/hwmon/exynos4_tmu.c
> +++ linux/drivers/hwmon/exynos4_tmu.c
> @@ -476,34 +476,38 @@ static int __devexit exynos4_tmu_remove(
>  }
>  
>  #ifdef CONFIG_PM
> -static int exynos4_tmu_suspend(struct platform_device *pdev, pm_message_t state)
> +static int exynos4_tmu_suspend(struct device *dev)
>  {
> -	exynos4_tmu_control(pdev, false);
> +	exynos4_tmu_control(to_platform_device(dev), false);
>  
>  	return 0;
>  }
>  
> -static int exynos4_tmu_resume(struct platform_device *pdev)
> +static int exynos4_tmu_resume(struct device *dev)
>  {
> +	struct platform_device *pdev = to_platform_device(dev);
> +
>  	exynos4_tmu_initialize(pdev);
>  	exynos4_tmu_control(pdev, true);
>  
>  	return 0;
>  }
> +
> +static SIMPLE_DEV_PM_OPS(exynos4_tmu_pm,
> +			 exynos4_tmu_suspend, exynos4_tmu_resume);
> +#define EXYNOS4_TMU_PM	(&exynos4_tmu_pm)
>  #else
> -#define exynos4_tmu_suspend NULL
> -#define exynos4_tmu_resume NULL
> +#define EXYNOS4_TMU_PM	NULL
>  #endif

Actually, looking into other drivers, the common approach seems to be to declare

static SIMPLE_DEV_PM_OPS(exynos4_tmu_pm,
			 exynos4_tmu_suspend, exynos4_tmu_resume);

outside the #ifdef code and then just assign

		.pm = &exynos4_tmu_pm;

unconditionally.

That seems to be a much simpler solution. Any special reason for not
implementing it this way ? Same question applies to the other patches in the
series.

Thanks,
Guenter

>  
>  static struct platform_driver exynos4_tmu_driver = {
>  	.driver = {
>  		.name   = "exynos4-tmu",
>  		.owner  = THIS_MODULE,
> +		.pm     = EXYNOS4_TMU_PM,
>  	},
>  	.probe = exynos4_tmu_probe,
>  	.remove	= __devexit_p(exynos4_tmu_remove),
> -	.suspend = exynos4_tmu_suspend,
> -	.resume = exynos4_tmu_resume,
>  };
>  
>  module_platform_driver(exynos4_tmu_driver);
> 
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