linux-kernel - Re: [PATCH] backlight: pwm_bl: move suspend/resume entries from platform

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Message-ID: <4F0FFA58.7010702@cn.fujitsu.com>
Date:	Fri, 13 Jan 2012 17:33:12 +0800
From:	Wanlong Gao <gaowanlong@...fujitsu.com>
To:	Barry Song <Barry.Song@....com>
CC:	Richard Purdie <rpurdie@...ys.net>,
	Eric Miao <eric.y.miao@...il.com>,
	linux-kernel@...r.kernel.org, workgroup.linux@....com,
	linux-arm-kernel@...ts.infradead.org,
	Xiangzhen Ye <Xiangzhen.Ye@....com>,
	Barry Song <Baohua.Song@....com>
Subject: Re: [PATCH] backlight: pwm_bl: move suspend/resume entries from platform_driver
 to driver.pm

On 12/01/2011 09:53 AM, Barry Song wrote:

> From: Xiangzhen Ye <Xiangzhen.Ye@....com>
> 
> At first, people are moving suspend/resume entries from platform_driver
> to driver.pm for many drivers.
> On the other hand, if we use swsusp to do hibernation for an embedded
> system using pwm_bl, in the process of preparing snapshot, backlight
> will be off and make lcd black screen. This gives bad user experiences.
> This patch will fix this issue as swsusp will go to call pm.freeze()
> but not platform_driver.suspend. we have no pm.freeze() for pwm_bl, so
> the lcd black screen will disappear.
> 
> Signed-off-by: Xiangzhen Ye <Xiangzhen.Ye@....com>
> Signed-off-by: Barry Song <Baohua.Song@....com>
> ---
>  drivers/video/backlight/pwm_bl.c |   15 ++++++++++-----
>  1 files changed, 10 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/video/backlight/pwm_bl.c b/drivers/video/backlight/pwm_bl.c
> index 8b5b2a4..50f3134 100644
> --- a/drivers/video/backlight/pwm_bl.c
> +++ b/drivers/video/backlight/pwm_bl.c
> @@ -169,9 +169,9 @@ static int pwm_backlight_remove(struct platform_device *pdev)
>  }
>  
>  #ifdef CONFIG_PM
> -static int pwm_backlight_suspend(struct platform_device *pdev,
> -				 pm_message_t state)
> +static int pwm_backlight_suspend(struct device *dev)
>  {
> +	struct platform_device *pdev = to_platform_device(dev);
>  	struct backlight_device *bl = platform_get_drvdata(pdev);
>  	struct pwm_bl_data *pb = dev_get_drvdata(&bl->dev);
>  
> @@ -184,8 +184,9 @@ static int pwm_backlight_suspend(struct platform_device *pdev,
>  	return 0;
>  }
>  
> -static int pwm_backlight_resume(struct platform_device *pdev)
> +static int pwm_backlight_resume(struct device *dev)
>  {
> +	struct platform_device *pdev = to_platform_device(dev);
>  	struct backlight_device *bl = platform_get_drvdata(pdev);
>  
>  	backlight_update_status(bl);
> @@ -196,15 +197,19 @@ static int pwm_backlight_resume(struct platform_device *pdev)
>  #define pwm_backlight_resume	NULL
>  #endif
>  
> +static const struct dev_pm_ops pwm_backlight_pm_ops = {
> +	.suspend = pwm_backlight_suspend,
> +	.resume = pwm_backlight_resume,
> +};


Why not use SIMPLE_DEV_PM_OPS instead?

Thanks
-Wanlong Gao

> +
>  static struct platform_driver pwm_backlight_driver = {
>  	.driver		= {
>  		.name	= "pwm-backlight",
>  		.owner	= THIS_MODULE,
> +		.pm	= &pwm_backlight_pm_ops,
>  	},
>  	.probe		= pwm_backlight_probe,
>  	.remove		= pwm_backlight_remove,
> -	.suspend	= pwm_backlight_suspend,
> -	.resume		= pwm_backlight_resume,
>  };
>  
>  static int __init pwm_backlight_init(void)


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