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Date: Tue, 23 May 2017 14:47:40 +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 1/2] backlight: gpio: Convert to use GPIO descriptor
On 30/04/17 09:17, Linus Walleij wrote:
> This driver is predominantly used by device tree systems, all
> of which can deal with modern GPIO descriptors. The legacy
> GPIO API is only used by one SH board so make the GPIO
> descriptor the default way to deal with it.
Every time I've reviewed previously I kind of got tripped up here and
decided to defer the review "until I had more time". I've since realized
I should probably just trust you on this bit and read the backlight code
instead ;-).
> As an intended side effect we do not need to look around in
> the device tree for the inversion flag since the GPIO
> descriptors will intrinsically deal with this.
>
> Signed-off-by: Linus Walleij <linus.walleij@...aro.org>
Only a tiny, tiny nit from me and, with that change:
Acked-by: Daniel Thompson <daniel.thompson@...aro.org>
> ---
> drivers/video/backlight/gpio_backlight.c | 74 ++++++++++++++++++++------------
> 1 file changed, 46 insertions(+), 28 deletions(-)
>
> diff --git a/drivers/video/backlight/gpio_backlight.c b/drivers/video/backlight/gpio_backlight.c
> index 18134416b154..17dd8071ad4d 100644
> --- a/drivers/video/backlight/gpio_backlight.c
> +++ b/drivers/video/backlight/gpio_backlight.c
> @@ -9,7 +9,8 @@
> #include <linux/backlight.h>
> #include <linux/err.h>
> #include <linux/fb.h>
> -#include <linux/gpio.h>
> +#include <linux/gpio.h> /* Only for legacy support */
> +#include <linux/gpio/consumer.h>
> #include <linux/init.h>
> #include <linux/kernel.h>
> #include <linux/module.h>
> @@ -23,7 +24,7 @@ struct gpio_backlight {
> struct device *dev;
> struct device *fbdev;
>
> - int gpio;
> + struct gpio_desc *gpiod;
> int active;
> int def_value;
> };
> @@ -38,8 +39,8 @@ static int gpio_backlight_update_status(struct backlight_device *bl)
> bl->props.state & (BL_CORE_SUSPENDED | BL_CORE_FBBLANK))
> brightness = 0;
>
> - gpio_set_value_cansleep(gbl->gpio,
> - brightness ? gbl->active : !gbl->active);
> + gpiod_set_value_cansleep(gbl->gpiod,
> + brightness ? gbl->active : !gbl->active);
>
> return 0;
> }
> @@ -61,23 +62,30 @@ static const struct backlight_ops gpio_backlight_ops = {
> 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;
> + struct device *dev = &pdev->dev;
> + struct device_node *np = dev->of_node;
> + enum gpiod_flags flags;
> + int ret;
> +
> + gbl->def_value = of_property_read_bool(np, "default-on");
> + if (gbl->def_value)
> + flags = GPIOD_OUT_HIGH;
> + else
> + flags = GPIOD_OUT_LOW;
Would prefer ternary here (like other flags assignments)...
> + /* GPIO descriptors keep track of inversion */
> + gbl->active = 1;
>
> - gbl->gpio = of_get_gpio_flags(np, 0, &gpio_flags);
> + gbl->gpiod = devm_gpiod_get(dev, NULL, flags);
> + if (IS_ERR(gbl->gpiod)) {
> + ret = PTR_ERR(gbl->gpiod);
>
> - if (!gpio_is_valid(gbl->gpio)) {
> - if (gbl->gpio != -EPROBE_DEFER) {
> - dev_err(&pdev->dev,
> + if (ret != -EPROBE_DEFER) {
> + dev_err(dev,
> "Error: The gpios parameter is missing or invalid.\n");
> }
> - return gbl->gpio;
> + return ret;
> }
>
> - gbl->active = (gpio_flags & OF_GPIO_ACTIVE_LOW) ? 0 : 1;
> -
> - gbl->def_value = of_property_read_bool(np, "default-on");
> -
> return 0;
> }
>
> @@ -89,7 +97,6 @@ static int gpio_backlight_probe(struct platform_device *pdev)
> struct backlight_device *bl;
> struct gpio_backlight *gbl;
> struct device_node *np = pdev->dev.of_node;
> - unsigned long flags = GPIOF_DIR_OUT;
> int ret;
>
> if (!pdata && !np) {
> @@ -109,22 +116,33 @@ static int gpio_backlight_probe(struct platform_device *pdev)
> if (ret)
> return ret;
> } else {
> + /*
> + * Legacy platform data GPIO retrieveal. Do not expand
> + * the use of this code path, currently only used by one
> + * SH board.
> + */
> + unsigned long flags = GPIOF_DIR_OUT;
> +
> gbl->fbdev = pdata->fbdev;
> - gbl->gpio = pdata->gpio;
> 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;
>
> - ret = devm_gpio_request_one(gbl->dev, gbl->gpio, flags,
> - pdata ? pdata->name : "backlight");
> - if (ret < 0) {
> - dev_err(&pdev->dev, "unable to request GPIO\n");
> - return ret;
> + if (gbl->active)
> + flags |= gbl->def_value ?
> + GPIOF_INIT_HIGH : GPIOF_INIT_LOW;
> + else
> + flags |= gbl->def_value ?
> + GPIOF_INIT_LOW : GPIOF_INIT_HIGH;
> +
> + ret = devm_gpio_request_one(gbl->dev, pdata->gpio, flags,
> + pdata ? pdata->name : "backlight");
> + if (ret < 0) {
> + dev_err(&pdev->dev, "unable to request GPIO\n");
> + return ret;
> + }
> + gbl->gpiod = gpio_to_desc(pdata->gpio);
> + if (!gbl->gpiod)
> + return -EINVAL;
> }
>
> memset(&props, 0, sizeof(props));
>
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