linux-kernel - Re: [PATCH 2/2] backlight: gpio: delete pdata inversion

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Message-ID: <20170523151455.o5mofjoiuovq6rq5@earth>
Date:   Tue, 23 May 2017 17:14:55 +0200
From:   Sebastian Reichel <sebastian.reichel@...labora.co.uk>
To:     Daniel Thompson <daniel.thompson@...aro.org>
Cc:     Linus Walleij <linus.walleij@...aro.org>,
        Lee Jones <lee.jones@...aro.org>,
        Jingoo Han <jingoohan1@...il.com>,
        linux-kernel@...r.kernel.org,
        Laurent Pinchart <Laurent.pinchart@...asonboard.com>
Subject: Re: [PATCH 2/2] backlight: gpio: delete pdata inversion

On Tue, May 23, 2017 at 03:15:01PM +0100, Daniel Thompson wrote:
> On 30/04/17 09:17, Linus Walleij wrote:
> > The option to invert the output of the GPIO (active low) is
> > not used by the only platform still using platform data to
> > set up a GPIO backlight (one SH board). Delete the option
> > as we do not expect to expand the use of board files for
> > this driver, and GPIO descriptors intrinsically keep track
> > of any signal inversion.
> > 
> > Signed-off-by: Linus Walleij <linus.walleij@...aro.org>
> 
> I note that only ~40% of Linux architectures currently have DT support at
> this point... There are still a few "embedded" ones that make do with
> platform bus (although they are growing increasingly niche).
> 
> Having said that I can't argue with "it's not used anywhere" (I've only
> really posted the above paragraph as a hint for future archeology... since
> it might be me doing the digging):
> Acked-by: Daniel Thompson <daniel.thompson@...aro.org>

Just for the record, if somebody needs to use board files, the
gpio subsystem provides gpiod_lookup_table instead, as described
in: Documentation/gpio/board.txt.

-- Sebastian

> > ---
> >   drivers/video/backlight/gpio_backlight.c     | 15 ++-------------
> >   include/linux/platform_data/gpio_backlight.h |  1 -
> >   2 files changed, 2 insertions(+), 14 deletions(-)
> > 
> > diff --git a/drivers/video/backlight/gpio_backlight.c b/drivers/video/backlight/gpio_backlight.c
> > index 17dd8071ad4d..8c19dc6c9236 100644
> > --- a/drivers/video/backlight/gpio_backlight.c
> > +++ b/drivers/video/backlight/gpio_backlight.c
> > @@ -25,7 +25,6 @@ struct gpio_backlight {
> >   	struct device *fbdev;
> >   	struct gpio_desc *gpiod;
> > -	int active;
> >   	int def_value;
> >   };
> > @@ -39,8 +38,7 @@ static int gpio_backlight_update_status(struct backlight_device *bl)
> >   	    bl->props.state & (BL_CORE_SUSPENDED | BL_CORE_FBBLANK))
> >   		brightness = 0;
> > -	gpiod_set_value_cansleep(gbl->gpiod,
> > -				 brightness ? gbl->active : !gbl->active);
> > +	gpiod_set_value_cansleep(gbl->gpiod, brightness);
> >   	return 0;
> >   }
> > @@ -72,8 +70,6 @@ static int gpio_backlight_probe_dt(struct platform_device *pdev,
> >   		flags = GPIOD_OUT_HIGH;
> >   	else
> >   		flags = GPIOD_OUT_LOW;
> > -	/* GPIO descriptors keep track of inversion */
> > -	gbl->active = 1;
> >   	gbl->gpiod = devm_gpiod_get(dev, NULL, flags);
> >   	if (IS_ERR(gbl->gpiod)) {
> > @@ -124,15 +120,8 @@ static int gpio_backlight_probe(struct platform_device *pdev)
> >   		unsigned long flags = GPIOF_DIR_OUT;
> >   		gbl->fbdev = pdata->fbdev;
> > -		gbl->active = pdata->active_low ? 0 : 1;
> >   		gbl->def_value = pdata->def_value;
> > -
> > -		if (gbl->active)
> > -			flags |= gbl->def_value ?
> > -				GPIOF_INIT_HIGH : GPIOF_INIT_LOW;
> > -		else
> > -			flags |= gbl->def_value ?
> > -				GPIOF_INIT_LOW : GPIOF_INIT_HIGH;
> > +		flags |= gbl->def_value ? GPIOF_INIT_HIGH : GPIOF_INIT_LOW;
> >   		ret = devm_gpio_request_one(gbl->dev, pdata->gpio, flags,
> >   					    pdata ? pdata->name : "backlight");
> > diff --git a/include/linux/platform_data/gpio_backlight.h b/include/linux/platform_data/gpio_backlight.h
> > index 5ae0d9c80d4d..683d90453c41 100644
> > --- a/include/linux/platform_data/gpio_backlight.h
> > +++ b/include/linux/platform_data/gpio_backlight.h
> > @@ -14,7 +14,6 @@ struct gpio_backlight_platform_data {
> >   	struct device *fbdev;
> >   	int gpio;
> >   	int def_value;
> > -	bool active_low;
> >   	const char *name;
> >   };
> > 
> 

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