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From:   Bartosz Golaszewski <brgl@bgdev.pl>
Date:   Thu, 3 Oct 2019 10:42:21 +0200
Message-ID: <CAMRc=MeKFG=gyogSn+WdUXwhHZE74-FwVfxgKrHNpScbFZFZrg@mail.gmail.com>
Subject: Re: [PATCH v4 7/7] backlight: gpio: pull gpio_backlight_initial_power_state()
 into probe
To:     Daniel Thompson <daniel.thompson@linaro.org>
Cc:     Yoshinori Sato <ysato@users.sourceforge.jp>,
        Rich Felker <dalias@libc.org>,
        Lee Jones <lee.jones@linaro.org>,
        Jingoo Han <jingoohan1@gmail.com>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>,
        Linus Walleij <linus.walleij@linaro.org>,
        Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
        Jacopo Mondi <jacopo@jmondi.org>, linux-sh@vger.kernel.org,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        dri-devel@lists.freedesktop.org, linux-fbdev@vger.kernel.org,
        Bartosz Golaszewski <bgolaszewski@baylibre.com>
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=C5=9Br., 2 pa=C5=BA 2019 o 16:40 Daniel Thompson <daniel.thompson@linaro.o=
rg> napisa=C5=82(a):
>
> On Wed, Oct 02, 2019 at 01:46:17PM +0200, Bartosz Golaszewski wrote:
> > =C5=9Br., 2 pa=C5=BA 2019 o 12:33 Daniel Thompson <daniel.thompson@lina=
ro.org> napisa=C5=82(a):
> > >
> > > On Tue, Oct 01, 2019 at 02:58:37PM +0200, Bartosz Golaszewski wrote:
> > > > From: Bartosz Golaszewski <bgolaszewski@baylibre.com>
> > > >
> > > > The probe function in the gpio-backlight driver is quite short. If =
we
> > > > pull gpio_backlight_initial_power_state() into probe we can drop tw=
o
> > > > more fields from struct gpio_backlight and shrink the driver code.
> > > >
> > > > Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
> > > > ---
> > > >  drivers/video/backlight/gpio_backlight.c | 36 ++++++++------------=
----
> > > >  1 file changed, 12 insertions(+), 24 deletions(-)
> > > >
> > > > diff --git a/drivers/video/backlight/gpio_backlight.c b/drivers/vid=
eo/backlight/gpio_backlight.c
> > > > index 6247687b6330..37ec184f0c5c 100644
> > > > --- a/drivers/video/backlight/gpio_backlight.c
> > > > +++ b/drivers/video/backlight/gpio_backlight.c
> > > > @@ -17,11 +17,8 @@
> > > >  #include <linux/slab.h>
> > > >
> > > >  struct gpio_backlight {
> > > > -     struct device *dev;
> > > >       struct device *fbdev;
> > > > -
> > > >       struct gpio_desc *gpiod;
> > > > -     int def_value;
> > > >  };
> > > >
> > > >  static int gpio_backlight_update_status(struct backlight_device *b=
l)
> > > > @@ -53,41 +50,24 @@ static const struct backlight_ops gpio_backligh=
t_ops =3D {
> > > >       .check_fb       =3D gpio_backlight_check_fb,
> > > >  };
> > > >
> > > > -static int gpio_backlight_initial_power_state(struct gpio_backligh=
t *gbl)
> > >
> > > I'm inclined to view deleting this function as removing a comment (e.=
g.
> > > the function name helps us to read the code)!
> > >
> >
> > Right, but why not just add a comment then?
>
> I guess you could add a comment but keeping it pulled out in a function
> makes it easier to compare against equivalent code in other drivers
> (such as pwm_bl).
>

The pwm driver seems to be the only one that has this function and
it's also much more complicated. Unless it's a hard NACK, I think that
pulling all initialization into probe looks better and shrinks the
driver visually.

Bart

>
> Daniel.
>
>
> > The probe function is 50
> > lines long, there's really no need to split it. This will get inlined
> > anyway too.
> >
> > Bart
> >
> > > Removing the variables from the context structure is good but why not
> > > just pass them to the function and let the compiler decided whether o=
r
> > > not to inline.
> > >
> > >
> > > Daniel.
> > >
> > >
> > > > -{
> > > > -     struct device_node *node =3D gbl->dev->of_node;
> > > > -
> > > > -     /* Not booted with device tree or no phandle link to the node=
 */
> > > > -     if (!node || !node->phandle)
> > > > -             return gbl->def_value ? FB_BLANK_UNBLANK : FB_BLANK_P=
OWERDOWN;
> > > > -
> > > > -     /* if the enable GPIO is disabled, do not enable the backligh=
t */
> > > > -     if (gpiod_get_value_cansleep(gbl->gpiod) =3D=3D 0)
> > > > -             return FB_BLANK_POWERDOWN;
> > > > -
> > > > -     return FB_BLANK_UNBLANK;
> > > > -}
> > > > -
> > > > -
> > > >  static int gpio_backlight_probe(struct platform_device *pdev)
> > > >  {
> > > >       struct device *dev =3D &pdev->dev;
> > > >       struct gpio_backlight_platform_data *pdata =3D dev_get_platda=
ta(dev);
> > > > +     struct device_node *of_node =3D dev->of_node;
> > > >       struct backlight_properties props;
> > > >       struct backlight_device *bl;
> > > >       struct gpio_backlight *gbl;
> > > > -     int ret;
> > > > +     int ret, def_value;
> > > >
> > > >       gbl =3D devm_kzalloc(dev, sizeof(*gbl), GFP_KERNEL);
> > > >       if (gbl =3D=3D NULL)
> > > >               return -ENOMEM;
> > > >
> > > > -     gbl->dev =3D dev;
> > > > -
> > > >       if (pdata)
> > > >               gbl->fbdev =3D pdata->fbdev;
> > > >
> > > > -     gbl->def_value =3D device_property_read_bool(dev, "default-on=
");
> > > > +     def_value =3D device_property_read_bool(dev, "default-on");
> > > >
> > > >       gbl->gpiod =3D devm_gpiod_get(dev, NULL, GPIOD_ASIS);
> > > >       if (IS_ERR(gbl->gpiod)) {
> > > > @@ -109,7 +89,15 @@ static int gpio_backlight_probe(struct platform=
_device *pdev)
> > > >               return PTR_ERR(bl);
> > > >       }
> > > >
> > > > -     bl->props.power =3D gpio_backlight_initial_power_state(gbl);
> > > > +     /* Not booted with device tree or no phandle link to the node=
 */
> > > > +     if (!of_node || !of_node->phandle)
> > > > +             bl->props.power =3D def_value ? FB_BLANK_UNBLANK
> > > > +                                         : FB_BLANK_POWERDOWN;
> > > > +     else if (gpiod_get_value_cansleep(gbl->gpiod) =3D=3D 0)
> > > > +             bl->props.power =3D FB_BLANK_POWERDOWN;
> > > > +     else
> > > > +             bl->props.power =3D FB_BLANK_UNBLANK;
> > > > +
> > > >       bl->props.brightness =3D 1;
> > > >
> > > >       backlight_update_status(bl);
> > > > --
> > > > 2.23.0
> > > >