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

[Jingoo Han]

On Saturday, November 24, 2012 1:35 AM, Laurent Pinchart wrote
> 
> Signed-off-by: Laurent Pinchart <laurent.pinch...@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;
> +}