linux-kernel - Re: [PATCH] backlight: da903x_bl: switch to using SIMPLE_DEV_PM

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Date:	Tue, 12 Mar 2013 20:02:42 +0100
From:	Lars-Peter Clausen <lars@...afoo.de>
To:	Jingoo Han <jg1.han@...sung.com>
CC:	'Andrew Morton' <akpm@...ux-foundation.org>,
	'LKML' <linux-kernel@...r.kernel.org>,
	'Richard Purdie' <rpurdie@...ys.net>
Subject: Re: [PATCH] backlight: da903x_bl: switch to using SIMPLE_DEV_PM_OPS

On 03/12/2013 06:48 AM, Jingoo Han wrote:
> This reduces #ifdefs in the code. Also, CONFIG_PM_SLEEP is used
> to avoid warnings of unused functions if CONFIG_PM_SLEEP is not
> defined.
> 
> Signed-off-by: Jingoo Han <jg1.han@...sung.com>

I think you can eliminate the suspend/resume functions all together by using
the blacklight subsystems CORE_SUSPENDRESUME feature.

E.g.

diff --git a/drivers/video/backlight/da903x_bl.c
b/drivers/video/backlight/da903x_bl.c
index 8179cef..80ba6b3 100644
--- a/drivers/video/backlight/da903x_bl.c
+++ b/drivers/video/backlight/da903x_bl.c
@@ -88,6 +88,9 @@ static int da903x_backlight_update_status(struct
 	if (bl->props.fb_blank != FB_BLANK_UNBLANK)
 		brightness = 0;

+	if (bl->props.state & BL_CORE_SUSPENDED)
+		brightness = 0;
+
 	return da903x_backlight_set(bl, brightness);
 }

@@ -100,6 +103,7 @@ static int da903x_backlight_get_brightness(struct
 static const struct backlight_ops da903x_backlight_ops = {
 	.update_status	= da903x_backlight_update_status,
 	.get_brightness	= da903x_backlight_get_brightness,
+	.options	= BL_CORE_SUSPENDRESUME,
 };

 static int da903x_backlight_probe(struct platform_device *pdev)
@@ -161,35 +165,10 @@ static int da903x_backlight_remove(struct
 	return 0;
 }

-#ifdef CONFIG_PM
-static int da903x_backlight_suspend(struct device *dev)
-{
-	struct backlight_device *bl = dev_get_drvdata(dev);
-
-	return da903x_backlight_set(bl, 0);
-}
-
-static int da903x_backlight_resume(struct device *dev)
-{
-	struct backlight_device *bl = dev_get_drvdata(dev);
-
-	backlight_update_status(bl);
-	return 0;
-}
-
-static const struct dev_pm_ops da903x_backlight_pm_ops = {
-	.suspend	= da903x_backlight_suspend,
-	.resume		= da903x_backlight_resume,
-};
-#endif
-
 static struct platform_driver da903x_backlight_driver = {
 	.driver		= {
 		.name	= "da903x-backlight",
 		.owner	= THIS_MODULE,
-#ifdef CONFIG_PM
-		.pm	= &da903x_backlight_pm_ops,
-#endif
 	},
 	.probe		= da903x_backlight_probe,
 	.remove		= da903x_backlight_remove,
--
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