linux-kernel - Re: [PATCH 1/5] backlight: Add GPIO-based backlight driver

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Message-ID: <50B347F4.2080705@metafoo.de>
Date:	Mon, 26 Nov 2012 11:44:04 +0100
From:	Lars-Peter Clausen <lars@...afoo.de>
To:	Laurent Pinchart <laurent.pinchart+renesas@...asonboard.com>
CC:	jg1.han@...sung.com,
	"akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-sh@...r.kernel.org" <linux-sh@...r.kernel.org>,
	"linux-fbdev@...r.kernel.org" <linux-fbdev@...r.kernel.org>,
	Paul Mundt <lethal@...ux-sh.org>,
	Magnus Damm <magnus.damm@...il.com>,
	Richard Purdie <rpurdie@...ys.net>,
	Kuninori Morimoto <kuninori.morimoto.gx@...esas.com>
Subject: Re: [PATCH 1/5] backlight: Add GPIO-based backlight driver

On 11/26/2012 10:49 AM, Jingoo Han wrote:
> On Saturday, November 24, 2012 1:35 AM, Laurent Pinchart wrote
[...]
>> +static int gpio_backlight_check_fb(struct backlight_device *bl,
>> +				   struct fb_info *info)
>> +{
>> +	struct gpio_backlight *gbl = bl_get_data(bl);
>> +
>> +	return gbl->fbdev == info->dev;

I think it makes sense to return true if fbdev is NULL, to provide a simple
fallback for systems with only one framebuffer device.

>> +}
>> +
[...]
>> +#ifdef CONFIG_PM
>> +static int gpio_backlight_suspend(struct device *dev)
>> +{
>> +	struct backlight_device *bl = dev_get_drvdata(dev);
>> +	struct gpio_backlight *gbl = bl_get_data(bl);
>> +
>> +	gpio_set_value(gbl->gpio, !gbl->active);
>> +
>> +	return 0;
>> +}
>> +
>> +static int gpio_backlight_resume(struct device *dev)
>> +{
>> +	struct backlight_device *bl = dev_get_drvdata(dev);
>> +
>> +	backlight_update_status(bl);
>> +	return 0;
>> +}

If you use BL_CORE_SUSPENDRESUME you can get rid of the custom
suspend/resume handlers.

>> +
>> +static SIMPLE_DEV_PM_OPS(gpio_backlight_pm_ops, gpio_backlight_suspend,
>> +			 gpio_backlight_resume);
>> +
>> +#endif
>> +
[...]
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