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

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

[Jingoo Han]

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On Saturday, November 24, 2012 1:35 AM, Laurent Pinchart wrote
> 
> Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

CC'ed Andrew Morton

It looks good. Also, I tested this patch with SMDK4210 board.
Acked-by: Jingoo Han <jg1.han@samsung.com>

Best regards,
Jingoo Han

> ---
>  drivers/video/backlight/Kconfig          |    7 ++
>  drivers/video/backlight/Makefile         |    1 +
>  drivers/video/backlight/gpio_backlight.c |  158 ++++++++++++++++++++++++++++++
>  include/video/gpio_backlight.h           |   21 ++++
>  4 files changed, 187 insertions(+), 0 deletions(-)
>  create mode 100644 drivers/video/backlight/gpio_backlight.c
>  create mode 100644 include/video/gpio_backlight.h
> 
> diff --git a/drivers/video/backlight/Kconfig b/drivers/video/backlight/Kconfig
> index 765a945..259442d 100644
> --- a/drivers/video/backlight/Kconfig
> +++ b/drivers/video/backlight/Kconfig
> @@ -390,6 +390,13 @@ config BACKLIGHT_TPS65217
>  	  If you have a Texas Instruments TPS65217 say Y to enable the
>  	  backlight driver.
> 
> +config BACKLIGHT_GPIO
> +	tristate "Generic GPIO based Backlight Driver"
> +	depends on GENERIC_GPIO
> +	help
> +	  If you have a LCD backlight adjustable by GPIO, say Y to enable
> +	  this driver.
> +
>  endif # BACKLIGHT_CLASS_DEVICE
> 
>  endif # BACKLIGHT_LCD_SUPPORT
> diff --git a/drivers/video/backlight/Makefile b/drivers/video/backlight/Makefile
> index e7ce729..ec91c4a 100644
> --- a/drivers/video/backlight/Makefile
> +++ b/drivers/video/backlight/Makefile
> @@ -45,3 +45,4 @@ obj-$(CONFIG_BACKLIGHT_PCF50633)	+= pcf50633-backlight.o
>  obj-$(CONFIG_BACKLIGHT_AAT2870) += aat2870_bl.o
>  obj-$(CONFIG_BACKLIGHT_OT200) += ot200_bl.o
>  obj-$(CONFIG_BACKLIGHT_TPS65217) += tps65217_bl.o
> +obj-$(CONFIG_BACKLIGHT_GPIO)	+= gpio_backlight.o
> diff --git a/drivers/video/backlight/gpio_backlight.c b/drivers/video/backlight/gpio_backlight.c
> new file mode 100644
> index 0000000..5a8cd34
> --- /dev/null
> +++ b/drivers/video/backlight/gpio_backlight.c
> @@ -0,0 +1,158 @@
> +/*
> + * gpio_backlight.c - Simple GPIO-controlled backlight
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + */
> +
> +#include <linux/backlight.h>
> +#include <linux/err.h>
> +#include <linux/fb.h>
> +#include <linux/gpio.h>
> +#include <linux/init.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +#include <linux/slab.h>
> +#include <video/gpio_backlight.h>
> +
> +struct gpio_backlight {
> +	struct device *dev;
> +	struct device *fbdev;
> +
> +	int gpio;
> +	int active;
> +};
> +
> +static int gpio_backlight_update_status(struct backlight_device *bl)
> +{
> +	struct gpio_backlight *gbl = bl_get_data(bl);
> +	int brightness = bl->props.brightness;
> +
> +	if (bl->props.power != FB_BLANK_UNBLANK ||
> +	    bl->props.fb_blank != FB_BLANK_UNBLANK ||
> +	    bl->props.state & (BL_CORE_SUSPENDED | BL_CORE_FBBLANK))
> +		brightness = 0;
> +
> +	gpio_set_value(gbl->gpio, brightness ? gbl->active : !gbl->active);
> +
> +	return 0;
> +}
> +
> +static int gpio_backlight_get_brightness(struct backlight_device *bl)
> +{
> +	return bl->props.brightness;
> +}
> +
> +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;
> +}
> +
> +static const struct backlight_ops gpio_backlight_ops = {
> +	.update_status	= gpio_backlight_update_status,
> +	.get_brightness	= gpio_backlight_get_brightness,
> +	.check_fb	= gpio_backlight_check_fb,
> +};
> +
> +#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;
> +}
> +
> +static SIMPLE_DEV_PM_OPS(gpio_backlight_pm_ops, gpio_backlight_suspend,
> +			 gpio_backlight_resume);
> +
> +#endif
> +
> +static int __devinit gpio_backlight_probe(struct platform_device *pdev)
> +{
> +	struct gpio_backlight_platform_data *pdata = pdev->dev.platform_data;
> +	struct backlight_properties props;
> +	struct backlight_device *bl;
> +	struct gpio_backlight *gbl;
> +	int ret;
> +
> +	gbl = devm_kzalloc(&pdev->dev, sizeof(*gbl), GFP_KERNEL);
> +	if (gbl == NULL)
> +		return -ENOMEM;
> +
> +	gbl->dev = &pdev->dev;
> +
> +	if (!pdata) {
> +		dev_err(&pdev->dev, "failed to find platform data\n");
> +		return -ENODEV;
> +	}
> +
> +	gbl->fbdev = pdata->fbdev;
> +	gbl->gpio = pdata->gpio;
> +	gbl->active = pdata->active_low ? 0 : 1;
> +
> +	ret = devm_gpio_request_one(gbl->dev, gbl->gpio, GPIOF_DIR_OUT,
> +				    pdata->name);
> +	if (ret < 0) {
> +		dev_err(&pdev->dev, "unable to request GPIO\n");
> +		return ret;
> +	}
> +
> +	memset(&props, 0, sizeof(props));
> +	props.type = BACKLIGHT_RAW;
> +	props.max_brightness = 1;
> +	bl = backlight_device_register(dev_name(&pdev->dev), &pdev->dev, gbl,
> +				       &gpio_backlight_ops, &props);
> +	if (IS_ERR(bl)) {
> +		dev_err(&pdev->dev, "failed to register backlight\n");
> +		return PTR_ERR(bl);
> +	}
> +
> +	bl->props.brightness = pdata->def_value;
> +	backlight_update_status(bl);
> +
> +	platform_set_drvdata(pdev, bl);
> +	return 0;
> +}
> +
> +static int __devexit gpio_backlight_remove(struct platform_device *pdev)
> +{
> +	struct backlight_device *bl = platform_get_drvdata(pdev);
> +
> +	backlight_device_unregister(bl);
> +	return 0;
> +}
> +
> +static struct platform_driver gpio_backlight_driver = {
> +	.driver		= {
> +		.name		= "gpio-backlight",
> +		.owner		= THIS_MODULE,
> +#ifdef CONFIG_PM
> +		.pm		= &gpio_backlight_pm_ops,
> +#endif
> +	},
> +	.probe		= gpio_backlight_probe,
> +	.remove		= __devexit_p(gpio_backlight_remove),
> +};
> +
> +module_platform_driver(gpio_backlight_driver);
> +
> +MODULE_AUTHOR("Laurent Pinchart <laurent.pinchart@ideasonboard.com>");
> +MODULE_DESCRIPTION("GPIO-based Backlight Driver");
> +MODULE_LICENSE("GPL");
> +MODULE_ALIAS("platform:gpio-backlight");
> diff --git a/include/video/gpio_backlight.h b/include/video/gpio_backlight.h
> new file mode 100644
> index 0000000..5ae0d9c
> --- /dev/null
> +++ b/include/video/gpio_backlight.h
> @@ -0,0 +1,21 @@
> +/*
> + * gpio_backlight.h - Simple GPIO-controlled backlight
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + */
> +#ifndef __GPIO_BACKLIGHT_H__
> +#define __GPIO_BACKLIGHT_H__
> +
> +struct device;
> +
> +struct gpio_backlight_platform_data {
> +	struct device *fbdev;
> +	int gpio;
> +	int def_value;
> +	bool active_low;
> +	const char *name;
> +};
> +
> +#endif
> --
> 1.7.8.6
> 
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Re: [PATCH 1/5] backlight: Add GPIO-based backlight driver

[Laurent Pinchart]

Hi Jingoo,

On Monday 26 November 2012 09:49:36 Jingoo Han wrote:
> On Saturday, November 24, 2012 1:35 AM, Laurent Pinchart wrote
> > 
> > Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> 
> CC'ed Andrew Morton
> 
> It looks good. Also, I tested this patch with SMDK4210 board.
> Acked-by: Jingoo Han <jg1.han@samsung.com>

Thank you.

Unless Richard wants to take 1/5 and 2/5, I plan to push them through either 
the Renesas ARM or Renesas SH tree with the board code patches.

-- 
Regards,

Laurent Pinchart

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

[Lars-Peter Clausen]

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
>> +
[...]

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

[Laurent Pinchart]

Hi Lars-Peter,

On Monday 26 November 2012 11:44:04 Lars-Peter Clausen wrote:
> 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.

Agreed, I'll change that.

> >> +}
> >> +
> 
> [...]
> 
> >> +#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.

Good point, I'll do that.

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

-- 
Regards,

Laurent Pinchart

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

[Jingoo Han]

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On Saturday, November 24, 2012 1:35 AM, Laurent Pinchart wrote
> 
> Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> ---
>  drivers/video/backlight/Kconfig          |    7 ++
>  drivers/video/backlight/Makefile         |    1 +
>  drivers/video/backlight/gpio_backlight.c |  158 ++++++++++++++++++++++++++++++
>  include/video/gpio_backlight.h           |   21 ++++
>  4 files changed, 187 insertions(+), 0 deletions(-)
>  create mode 100644 drivers/video/backlight/gpio_backlight.c
>  create mode 100644 include/video/gpio_backlight.h

[...]

> +static int __devinit gpio_backlight_probe(struct platform_device *pdev)
> +{
> +	struct gpio_backlight_platform_data *pdata = pdev->dev.platform_data;
> +	struct backlight_properties props;
> +	struct backlight_device *bl;
> +	struct gpio_backlight *gbl;
> +	int ret;
> +
> +	gbl = devm_kzalloc(&pdev->dev, sizeof(*gbl), GFP_KERNEL);
> +	if (gbl == NULL)
> +		return -ENOMEM;
> +
> +	gbl->dev = &pdev->dev;
> +
> +	if (!pdata) {
> +		dev_err(&pdev->dev, "failed to find platform data\n");
> +		return -ENODEV;
> +	}
> +
> +	gbl->fbdev = pdata->fbdev;
> +	gbl->gpio = pdata->gpio;
> +	gbl->active = pdata->active_low ? 0 : 1;
> +
> +	ret = devm_gpio_request_one(gbl->dev, gbl->gpio, GPIOF_DIR_OUT,
> +				    pdata->name);

Please use GPIOF_INIT flags if you want to turn off GPIO backlight.
If gbl->active is inverted, GPIOF_INIT_HIGH can be used as below:

	ret = devm_gpio_request_one(gbl->dev, gbl->gpio,
				    GPIOF_DIR_OUT | (gbl->active ?
				    GPIOF_INIT_LOW : GPIOF_INIT_HIGH),
				    pdata->name);

Best regards,
Jingoo Han

> +	if (ret < 0) {
> +		dev_err(&pdev->dev, "unable to request GPIO\n");
> +		return ret;
> +	}
> +
> +	memset(&props, 0, sizeof(props));
> +	props.type = BACKLIGHT_RAW;
> +	props.max_brightness = 1;
> +	bl = backlight_device_register(dev_name(&pdev->dev), &pdev->dev, gbl,
> +				       &gpio_backlight_ops, &props);
> +	if (IS_ERR(bl)) {
> +		dev_err(&pdev->dev, "failed to register backlight\n");
> +		return PTR_ERR(bl);
> +	}
> +
> +	bl->props.brightness = pdata->def_value;
> +	backlight_update_status(bl);
> +
> +	platform_set_drvdata(pdev, bl);
> +	return 0;
> +}


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

[Jingoo Han]

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On Monday, November 26, 2012 7:25 PM, Laurent Pinchart wrote
> 
> Hi Jingoo,
> 
> On Monday 26 November 2012 09:49:36 Jingoo Han wrote:
> > On Saturday, November 24, 2012 1:35 AM, Laurent Pinchart wrote
> > >
> > > Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> >
> > CC'ed Andrew Morton
> >
> > It looks good. Also, I tested this patch with SMDK4210 board.
> > Acked-by: Jingoo Han <jg1.han@samsung.com>
> 
> Thank you.
> 
> Unless Richard wants to take 1/5 and 2/5, I plan to push them through either
> the Renesas ARM or Renesas SH tree with the board code patches.

Hi Laurent,

OK, I see.
Maybe Richard won't take 1/5 and 2/5. As you mentioned, it would be good
to push them throughout the Renesas tree to avoid bisection breakages.

Best regards,
Jingoo Han


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

[Laurent Pinchart]

Hi Jingoo,

On Tuesday 27 November 2012 01:10:36 Jingoo Han wrote:
> On Saturday, November 24, 2012 1:35 AM, Laurent Pinchart wrote
> 
> > 
> > Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> > ---
> > 
> >  drivers/video/backlight/Kconfig          |    7 ++
> >  drivers/video/backlight/Makefile         |    1 +
> >  drivers/video/backlight/gpio_backlight.c |  158 +++++++++++++++++++++++++
> >  include/video/gpio_backlight.h           |   21 ++++
> >  4 files changed, 187 insertions(+), 0 deletions(-)
> >  create mode 100644 drivers/video/backlight/gpio_backlight.c
> >  create mode 100644 include/video/gpio_backlight.h
> 
> 
> [...]
> 
> 
> > +static int __devinit gpio_backlight_probe(struct platform_device *pdev)
> > +{
> > +	struct gpio_backlight_platform_data *pdata = pdev->dev.platform_data;
> > +	struct backlight_properties props;
> > +	struct backlight_device *bl;
> > +	struct gpio_backlight *gbl;
> > +	int ret;
> > +
> > +	gbl = devm_kzalloc(&pdev->dev, sizeof(*gbl), GFP_KERNEL);
> > +	if (gbl == NULL)
> > +		return -ENOMEM;
> > +
> > +	gbl->dev = &pdev->dev;
> > +
> > +	if (!pdata) {
> > +		dev_err(&pdev->dev, "failed to find platform data\n");
> > +		return -ENODEV;
> > +	}
> > +
> > +	gbl->fbdev = pdata->fbdev;
> > +	gbl->gpio = pdata->gpio;
> > +	gbl->active = pdata->active_low ? 0 : 1;
> > +
> > +	ret = devm_gpio_request_one(gbl->dev, gbl->gpio, GPIOF_DIR_OUT,
> > +				    pdata->name);
> 
> 
> Please use GPIOF_INIT flags if you want to turn off GPIO backlight.
> If gbl->active is inverted, GPIOF_INIT_HIGH can be used as below:
> 
> 	ret = devm_gpio_request_one(gbl->dev, gbl->gpio,
> 				    GPIOF_DIR_OUT | (gbl->active ?
> 				    GPIOF_INIT_LOW : GPIOF_INIT_HIGH),
> 				    pdata->name);

Good point, thank you. I'll fix that.

> > +	if (ret < 0) {
> > +		dev_err(&pdev->dev, "unable to request GPIO\n");
> > +		return ret;
> > +	}
> > +
> > +	memset(&props, 0, sizeof(props));
> > +	props.type = BACKLIGHT_RAW;
> > +	props.max_brightness = 1;
> > +	bl = backlight_device_register(dev_name(&pdev->dev), &pdev->dev, gbl,
> > +				       &gpio_backlight_ops, &props);
> > +	if (IS_ERR(bl)) {
> > +		dev_err(&pdev->dev, "failed to register backlight\n");
> > +		return PTR_ERR(bl);
> > +	}
> > +
> > +	bl->props.brightness = pdata->def_value;
> > +	backlight_update_status(bl);
> > +
> > +	platform_set_drvdata(pdev, bl);
> > +	return 0;
> > +}

-- 
Regards,

Laurent Pinchart