[PATCHv4] video: backlight: gpio-backlight: Add DT support.

Jean-Christophe PLAGNIOL-VILLARD
2013-10-22T05:11:57Z

On 00:48 Tue 22 Oct , Laurent Pinchart wrote:
> Hi Denis,
>
> Thanks for the patch. Please see below for a couple of small comment.
>
> On Monday 21 October 2013 11:13:33 Denis Carikli wrote:
> > Cc: Richard Purdie <rpurdie@rpsys.net>
> > Cc: Jingoo Han <jg1.han@samsung.com>
> > Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> > Cc: Rob Herring <rob.herring@calxeda.com>
> > Cc: Pawel Moll <pawel.moll@arm.com>
> > Cc: Mark Rutland <mark.rutland@arm.com>
> > Cc: Stephen Warren <swarren@wwwdotorg.org>
> > Cc: Ian Campbell <ijc+devicetree@hellion.org.uk>
> > Cc: devicetree at vger.kernel.org
> > Cc: Sascha Hauer <kernel@pengutronix.de>
> > Cc: linux-arm-kernel at lists.infradead.org
> > Cc: Lothar Wa?mann <LW@KARO-electronics.de>
> > Cc: Jean-Christophe Plagniol-Villard <plagnioj@jcrosoft.com>
> > Cc: Eric B?nard <eric@eukrea.com>
> > Signed-off-by: Denis Carikli <denis@eukrea.com>
> > ---
> > ChangeLog v3->v4:
> > - The default-brightness property is now optional, it defaults to 1 if not
> > set. - def_value int becomes an u32.
> > - gbl->def_value was set to pdata->def_value in pdata mode to avoid an extra
> > check.
> > ---
> > .../bindings/video/backlight/gpio-backlight.txt | 20 ++++++
> > drivers/video/backlight/gpio_backlight.c | 69 +++++++++++++++--
> > 2 files changed, 82 insertions(+), 7 deletions(-)
> > create mode 100644
> > Documentation/devicetree/bindings/video/backlight/gpio-backlight.txt
> >
> > diff --git
> > a/Documentation/devicetree/bindings/video/backlight/gpio-backlight.txt
> > b/Documentation/devicetree/bindings/video/backlight/gpio-backlight.txt new
> > file mode 100644
> > index 0000000..3474d4a
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/video/backlight/gpio-backlight.txt
> > @@ -0,0 +1,20 @@
> > +gpio-backlight bindings
> > +
> > +Required properties:
> > + - compatible: "gpio-backlight"
> > + - gpios: describes the gpio that is used for enabling/disabling the
> > backlight
> > + (see GPIO binding[0] for more details).
> > +
> > +Optional properties:
> > + - default-brightness-level: the default brightness level (can be 0(off)
> > or
> > + 1(on) since GPIOs only support theses levels).
>
> I believe you should specify what the default value is when the property isn't
> available.
>
> > +
> > +[0]: Documentation/devicetree/bindings/gpio/gpio.txt
> > +
> > +Example:
> > +
> > + backlight {
> > + compatible = "gpio-backlight";
> > + gpios = <&gpio3 4 0>;
> > + default-brightness-level = <0>;
> > + };
> > diff --git a/drivers/video/backlight/gpio_backlight.c
> > b/drivers/video/backlight/gpio_backlight.c index 81fb127..248124d 100644
> > --- a/drivers/video/backlight/gpio_backlight.c
> > +++ b/drivers/video/backlight/gpio_backlight.c
> > @@ -13,6 +13,8 @@
> > #include <linux/init.h>
> > #include <linux/kernel.h>
> > #include <linux/module.h>
> > +#include <linux/of.h>
> > +#include <linux/of_gpio.h>
> > #include <linux/platform_data/gpio_backlight.h>
> > #include <linux/platform_device.h>
> > #include <linux/slab.h>
> > @@ -23,6 +25,7 @@ struct gpio_backlight {
> >
> > int gpio;
> > int active;
> > + u32 def_value;
> > };
> >
> > static int gpio_backlight_update_status(struct backlight_device *bl)
> > @@ -60,6 +63,41 @@ static const struct backlight_ops gpio_backlight_ops = {
> > .check_fb = gpio_backlight_check_fb,
> > };
> >
> > +static int gpio_backlight_probe_dt(struct platform_device *pdev,
> > + struct gpio_backlight *gbl)
> > +{
> > + struct device_node *np = pdev->dev.of_node;
> > + enum of_gpio_flags gpio_flags;
> > + int ret;
> > +
> > + gbl->fbdev = NULL;
> > + gbl->gpio = of_get_gpio_flags(np, 0, &gpio_flags);
> > +
> > + gbl->active = (gpio_flags & OF_GPIO_ACTIVE_LOW) ? 0 : 1;
>
> I would move this line after the error check below.
>
> > +
> > + if (gbl->gpio == -EPROBE_DEFER) {
> > + return ERR_PTR(-EPROBE_DEFER);
>
> Any reason not to retrun -EPROBE_DEFER directly ?
>
> > + } else if (gbl->gpio < 0) {
> > + dev_err(&pdev->dev, "Error: gpios is a required parameter.\n");
> > + return gbl->gpio;
> > + }
>
> Maybe you would do something like
>
> if (gbl->gpio < 0) {
> if (gbl->gpio == -EPROBE_DEFER)
> dev_err(&pdev->dev, "Error: gpios is a required parameter.\n");
it's not an error it's that the gpio driver is not yet probed

so it's need to be !=
> return gbl->gpio;
> }
>
> > +
> > + ret = of_property_read_u32(np, "default-brightness-level",
> > + &gbl->def_value);
> > + if (ret < 0) {
> > + /* The property is optional. */
> > + gbl->def_value = 1;
> > + }
> > +
> > + if (gbl->def_value > 1) {
> > + dev_warn(&pdev->dev,
> > + "Warning: Invalid default-brightness-level value. Its value can
> be
> > either 0(off) or 1(on).\n");
>
> I believe a less verbose message (without the second sentence) would have
> done, but that's up to you.

as it's only 0 or 1 why not just use a boolean
>
> > + gbl->def_value = 1;
> > + }
> > +
> > + return 0;
> > +}
> > +
> > static int gpio_backlight_probe(struct platform_device *pdev)
> > {
> > struct gpio_backlight_platform_data *pdata =
> > @@ -67,10 +105,12 @@ static int gpio_backlight_probe(struct platform_device
> > *pdev) struct backlight_properties props;
> > struct backlight_device *bl;
> > struct gpio_backlight *gbl;
> > + struct device_node *np = pdev->dev.of_node;
> > int ret;
> >
> > - if (!pdata) {
> > - dev_err(&pdev->dev, "failed to find platform data\n");
> > + if (!pdata && !np) {
> > + dev_err(&pdev->dev,
> > + "failed to find platform data or device tree node.\n");
> > return -ENODEV;
> > }
> >
> > @@ -79,14 +119,22 @@ static int gpio_backlight_probe(struct platform_device
> > *pdev) return -ENOMEM;
> >
> > gbl->dev = &pdev->dev;
> > - gbl->fbdev = pdata->fbdev;
> > - gbl->gpio = pdata->gpio;
> > - gbl->active = pdata->active_low ? 0 : 1;
> > +
> > + if (np) {
> > + ret = gpio_backlight_probe_dt(pdev, gbl);
> > + if (ret)
> > + return ret;
> > + } else {
> > + gbl->fbdev = pdata->fbdev;
> > + gbl->gpio = pdata->gpio;
> > + gbl->active = pdata->active_low ? 0 : 1;
> > + gbl->def_value = pdata->def_value;
> > + }
> >
> > ret = devm_gpio_request_one(gbl->dev, gbl->gpio, GPIOF_DIR_OUT |
> > (gbl->active ? GPIOF_INIT_LOW
> >
> > : GPIOF_INIT_HIGH),
> >
> > - pdata->name);
> > + pdata ? pdata->name : "backlight");
> > if (ret < 0) {
> > dev_err(&pdev->dev, "unable to request GPIO\n");
> > return ret;
> > @@ -103,17 +151,24 @@ static int gpio_backlight_probe(struct platform_device
> > *pdev) return PTR_ERR(bl);
> > }
> >
> > - bl->props.brightness = pdata->def_value;
> > + bl->props.brightness = gbl->def_value;
> > +
> > backlight_update_status(bl);
> >
> > platform_set_drvdata(pdev, bl);
> > return 0;
> > }
> >
> > +static struct of_device_id gpio_backlight_of_match[] = {
> > + { .compatible = "gpio-backlight" },
> > + { /* sentinel */ }
> > +};
> > +
> > static struct platform_driver gpio_backlight_driver = {
> > .driver = {
> > .name = "gpio-backlight",
> > .owner = THIS_MODULE,
> > + .of_match_table = of_match_ptr(gpio_backlight_of_match),
> > },
> > .probe = gpio_backlight_probe,
> > };
> --
> Regards,
>
> Laurent Pinchart
>