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

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Date:   Tue, 23 May 2017 15:15:01 +0100
From:   Daniel Thompson <daniel.thompson@...aro.org>
To:     Linus Walleij <linus.walleij@...aro.org>,
        Lee Jones <lee.jones@...aro.org>,
        Jingoo Han <jingoohan1@...il.com>, linux-kernel@...r.kernel.org
Cc:     Laurent Pinchart <Laurent.pinchart@...asonboard.com>
Subject: Re: [PATCH 2/2] backlight: gpio: delete pdata inversion

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>


Daniel.


> ---
>   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;
>   };
>   
>