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

Hi Jingoo,

On Tuesday 27 November 2012 01:10:36 Jingoo Han wrote:

On Saturday, November 24, 2012 1:35 AM, Laurent Pinchart wrote

quoted

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

[...]

quoted

+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.

quoted

+	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