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

- List: linux-fbdev
- 2 messages, 2 authors
- Page: https://ratatoskr.run/linux-fbdev/2012/11/3963579/t

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

- From: Jingoo Han \<hidden\>
- Date: 2012-11-27 01:10:40 
- Message: https://ratatoskr.run/linux-fbdev/2012/11/3963579.md

```text
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```

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

- From: Laurent Pinchart \<laurent.pinchart@ideasonboard.com\>
- Date: 2012-11-27 11:53:20 
- Message: https://ratatoskr.run/linux-fbdev/2012/11/3963856.md

```text
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

```