[PATCH v4 0/7] backlight: gpio: simplify the driver

[PATCH v4 0/7] backlight: gpio: simplify the driver

[Bartosz Golaszewski]

From: Bartosz Golaszewski <bgolaszewski@baylibre.com>

While working on my other series related to gpio-backlight[1] I noticed
that we could simplify the driver if we made the only user of platform
data use GPIO lookups and device properties. This series tries to do
that.

The first patch adds all necessary data structures to ecovec24. Patch
2/7 unifies much of the code for both pdata and non-pdata cases. Patches
3-4/7 remove unused platform data fields. Last three patches contain
additional improvements for the GPIO backlight driver while we're already
modifying it.

I don't have access to this HW but hopefully this works. Only compile
tested.

[1] https://lkml.org/lkml/2019/6/25/900

v1 -> v2:
- rebased on top of v5.3-rc1 and adjusted to the recent changes from Andy
- added additional two patches with minor improvements

v2 -> v3:
- in patch 7/7: used initializers to set values for pdata and dev local vars

v3 -> v4:
- rebased on top of v5.4-rc1
- removed changes that are no longer relevant after commit ec665b756e6f
  ("backlight: gpio-backlight: Correct initial power state handling")
- added patch 7/7

Bartosz Golaszewski (7):
  backlight: gpio: remove unneeded include
  sh: ecovec24: add additional properties to the backlight device
  backlight: gpio: simplify the platform data handling
  sh: ecovec24: don't set unused fields in platform data
  backlight: gpio: remove unused fields from platform data
  backlight: gpio: use a helper variable for &pdev->dev
  backlight: gpio: pull gpio_backlight_initial_power_state() into probe

 arch/sh/boards/mach-ecovec24/setup.c         |  33 ++++--
 drivers/video/backlight/gpio_backlight.c     | 107 +++++--------------
 include/linux/platform_data/gpio_backlight.h |   3 -
 3 files changed, 52 insertions(+), 91 deletions(-)

-- 
2.23.0

[PATCH v4 1/7] backlight: gpio: remove unneeded include

[Bartosz Golaszewski]

From: Bartosz Golaszewski <bgolaszewski@baylibre.com>

We no longer use any symbols from of_gpio.h. Remove this include.

Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
---
 drivers/video/backlight/gpio_backlight.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/drivers/video/backlight/gpio_backlight.c b/drivers/video/backlight/gpio_backlight.c
index 18e053e4716c..7e1990199fae 100644
--- a/drivers/video/backlight/gpio_backlight.c
+++ b/drivers/video/backlight/gpio_backlight.c
@@ -12,7 +12,6 @@
 #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/property.h>
-- 
2.23.0

Re: [PATCH v4 1/7] backlight: gpio: remove unneeded include

[Andy Shevchenko]

On Tue, Oct 01, 2019 at 02:58:31PM +0200, Bartosz Golaszewski wrote:
> From: Bartosz Golaszewski <bgolaszewski@baylibre.com>
> 

Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

> We no longer use any symbols from of_gpio.h. Remove this include.
> 
> Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
> ---
>  drivers/video/backlight/gpio_backlight.c | 1 -
>  1 file changed, 1 deletion(-)
> 
> diff --git a/drivers/video/backlight/gpio_backlight.c b/drivers/video/backlight/gpio_backlight.c
> index 18e053e4716c..7e1990199fae 100644
> --- a/drivers/video/backlight/gpio_backlight.c
> +++ b/drivers/video/backlight/gpio_backlight.c
> @@ -12,7 +12,6 @@
>  #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/property.h>
> -- 
> 2.23.0
> 

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v4 1/7] backlight: gpio: remove unneeded include

[Daniel Thompson]

On Tue, Oct 01, 2019 at 02:58:31PM +0200, Bartosz Golaszewski wrote:
> From: Bartosz Golaszewski <bgolaszewski@baylibre.com>
> 
> We no longer use any symbols from of_gpio.h. Remove this include.
> 
> Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>

Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>

> ---
>  drivers/video/backlight/gpio_backlight.c | 1 -
>  1 file changed, 1 deletion(-)
> 
> diff --git a/drivers/video/backlight/gpio_backlight.c b/drivers/video/backlight/gpio_backlight.c
> index 18e053e4716c..7e1990199fae 100644
> --- a/drivers/video/backlight/gpio_backlight.c
> +++ b/drivers/video/backlight/gpio_backlight.c
> @@ -12,7 +12,6 @@
>  #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/property.h>
> -- 
> 2.23.0
> 

Re: [PATCH v4 1/7] backlight: gpio: remove unneeded include

[Linus Walleij]

On Tue, Oct 1, 2019 at 2:59 PM Bartosz Golaszewski <brgl@bgdev.pl> wrote:

> From: Bartosz Golaszewski <bgolaszewski@baylibre.com>
>
> We no longer use any symbols from of_gpio.h. Remove this include.
>
> Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>

Reviewed-by: Linus Walleij <linus.walleij@linaro.org>

Thanks Bartosz,
Linus Walleij

[PATCH v4 2/7] sh: ecovec24: add additional properties to the backlight device

[Bartosz Golaszewski]

From: Bartosz Golaszewski <bgolaszewski@baylibre.com>

Add a GPIO lookup entry and a device property for GPIO backlight to the
board file. Tie them to the platform device which is now registered using
platform_device_register_full() because of the properties. These changes
are inactive now but will be used once the gpio backlight driver is
modified.

Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
---
 arch/sh/boards/mach-ecovec24/setup.c | 30 +++++++++++++++++++++++-----
 1 file changed, 25 insertions(+), 5 deletions(-)

diff --git a/arch/sh/boards/mach-ecovec24/setup.c b/arch/sh/boards/mach-ecovec24/setup.c
index acaa97459531..aaa8ea62636f 100644
--- a/arch/sh/boards/mach-ecovec24/setup.c
+++ b/arch/sh/boards/mach-ecovec24/setup.c
@@ -371,6 +371,19 @@ static struct platform_device lcdc_device = {
 	},
 };
 
+static struct gpiod_lookup_table gpio_backlight_lookup = {
+	.dev_id		= "gpio-backlight.0",
+	.table = {
+		GPIO_LOOKUP("sh7724_pfc", GPIO_PTR1, NULL, GPIO_ACTIVE_HIGH),
+		{ }
+	},
+};
+
+static struct property_entry gpio_backlight_props[] = {
+	PROPERTY_ENTRY_BOOL("default-on"),
+	{ }
+};
+
 static struct gpio_backlight_platform_data gpio_backlight_data = {
 	.fbdev = &lcdc_device.dev,
 	.gpio = GPIO_PTR1,
@@ -378,13 +391,15 @@ static struct gpio_backlight_platform_data gpio_backlight_data = {
 	.name = "backlight",
 };
 
-static struct platform_device gpio_backlight_device = {
+static const struct platform_device_info gpio_backlight_device_info = {
 	.name = "gpio-backlight",
-	.dev = {
-		.platform_data = &gpio_backlight_data,
-	},
+	.data = &gpio_backlight_data,
+	.size_data = sizeof(gpio_backlight_data),
+	.properties = gpio_backlight_props,
 };
 
+static struct platform_device *gpio_backlight_device;
+
 /* CEU0 */
 static struct ceu_platform_data ceu0_pdata = {
 	.num_subdevs			= 2,
@@ -1006,7 +1021,6 @@ static struct platform_device *ecovec_devices[] __initdata = {
 	&usb1_common_device,
 	&usbhs_device,
 	&lcdc_device,
-	&gpio_backlight_device,
 	&keysc_device,
 	&cn12_power,
 #if defined(CONFIG_MMC_SDHI) || defined(CONFIG_MMC_SDHI_MODULE)
@@ -1462,6 +1476,12 @@ static int __init arch_setup(void)
 #endif
 #endif
 
+	gpiod_add_lookup_table(&gpio_backlight_lookup);
+	gpio_backlight_device = platform_device_register_full(
+					&gpio_backlight_device_info);
+	if (IS_ERR(gpio_backlight_device))
+		return PTR_ERR(gpio_backlight_device);
+
 	return platform_add_devices(ecovec_devices,
 				    ARRAY_SIZE(ecovec_devices));
 }
-- 
2.23.0

[PATCH v4 3/7] backlight: gpio: simplify the platform data handling

[Bartosz Golaszewski]

From: Bartosz Golaszewski <bgolaszewski@baylibre.com>

Now that the last user of platform data (sh ecovec24) defines a proper
GPIO lookup and sets the 'default-on' device property, we can drop the
platform_data-specific GPIO handling and unify a big chunk of code.

The only field used from the platform data is now the fbdev pointer.

Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---
 drivers/video/backlight/gpio_backlight.c | 62 +++++-------------------
 1 file changed, 11 insertions(+), 51 deletions(-)

diff --git a/drivers/video/backlight/gpio_backlight.c b/drivers/video/backlight/gpio_backlight.c
index 7e1990199fae..20c5311c7ed2 100644
--- a/drivers/video/backlight/gpio_backlight.c
+++ b/drivers/video/backlight/gpio_backlight.c
@@ -6,7 +6,6 @@
 #include <linux/backlight.h>
 #include <linux/err.h>
 #include <linux/fb.h>
-#include <linux/gpio.h> /* Only for legacy support */
 #include <linux/gpio/consumer.h>
 #include <linux/init.h>
 #include <linux/kernel.h>
@@ -54,28 +53,6 @@ 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 *dev = &pdev->dev;
-	int ret;
-
-	gbl->def_value = device_property_read_bool(dev, "default-on");
-
-	gbl->gpiod = devm_gpiod_get(dev, NULL, GPIOD_ASIS);
-	if (IS_ERR(gbl->gpiod)) {
-		ret = PTR_ERR(gbl->gpiod);
-
-		if (ret != -EPROBE_DEFER) {
-			dev_err(dev,
-				"Error: The gpios parameter is missing or invalid.\n");
-		}
-		return ret;
-	}
-
-	return 0;
-}
-
 static int gpio_backlight_initial_power_state(struct gpio_backlight *gbl)
 {
 	struct device_node *node = gbl->dev->of_node;
@@ -107,35 +84,18 @@ static int gpio_backlight_probe(struct platform_device *pdev)
 
 	gbl->dev = &pdev->dev;
 
-	if (pdev->dev.fwnode) {
-		ret = gpio_backlight_probe_dt(pdev, gbl);
-		if (ret)
-			return ret;
-	} else if (pdata) {
-		/*
-		 * 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;
-
+	if (pdata)
 		gbl->fbdev = pdata->fbdev;
-		gbl->def_value = pdata->def_value;
-		flags |= gbl->def_value ? GPIOF_INIT_HIGH : GPIOF_INIT_LOW;
-
-		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;
-	} else {
-		dev_err(&pdev->dev,
-			"failed to find platform data or device tree node.\n");
-		return -ENODEV;
+
+	gbl->def_value = device_property_read_bool(&pdev->dev, "default-on");
+
+	gbl->gpiod = devm_gpiod_get(&pdev->dev, NULL, GPIOD_ASIS);
+	if (IS_ERR(gbl->gpiod)) {
+		ret = PTR_ERR(gbl->gpiod);
+		if (ret != -EPROBE_DEFER)
+			dev_err(&pdev->dev,
+				"Error: The gpios parameter is missing or invalid.\n");
+		return ret;
 	}
 
 	memset(&props, 0, sizeof(props));
-- 
2.23.0

[PATCH v4 4/7] sh: ecovec24: don't set unused fields in platform data

[Bartosz Golaszewski]

From: Bartosz Golaszewski <bgolaszewski@baylibre.com>

Platform data fields other than fbdev are no longer used by the
backlight driver. Remove them.

Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
---
 arch/sh/boards/mach-ecovec24/setup.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/arch/sh/boards/mach-ecovec24/setup.c b/arch/sh/boards/mach-ecovec24/setup.c
index aaa8ea62636f..dd427bac5cde 100644
--- a/arch/sh/boards/mach-ecovec24/setup.c
+++ b/arch/sh/boards/mach-ecovec24/setup.c
@@ -386,9 +386,6 @@ static struct property_entry gpio_backlight_props[] = {
 
 static struct gpio_backlight_platform_data gpio_backlight_data = {
 	.fbdev = &lcdc_device.dev,
-	.gpio = GPIO_PTR1,
-	.def_value = 1,
-	.name = "backlight",
 };
 
 static const struct platform_device_info gpio_backlight_device_info = {
-- 
2.23.0

[PATCH v4 5/7] backlight: gpio: remove unused fields from platform data

[Bartosz Golaszewski]

From: Bartosz Golaszewski <bgolaszewski@baylibre.com>

Remove the platform data fields that nobody uses.

Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
---
 include/linux/platform_data/gpio_backlight.h | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/include/linux/platform_data/gpio_backlight.h b/include/linux/platform_data/gpio_backlight.h
index 34179d600360..1a8b5b1946fe 100644
--- a/include/linux/platform_data/gpio_backlight.h
+++ b/include/linux/platform_data/gpio_backlight.h
@@ -9,9 +9,6 @@ struct device;
 
 struct gpio_backlight_platform_data {
 	struct device *fbdev;
-	int gpio;
-	int def_value;
-	const char *name;
 };
 
 #endif
-- 
2.23.0

[PATCH v4 6/7] backlight: gpio: use a helper variable for &pdev->dev

[Bartosz Golaszewski]

From: Bartosz Golaszewski <bgolaszewski@baylibre.com>

Instead of dereferencing pdev each time, use a helper variable for
the associated device pointer.

Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---
 drivers/video/backlight/gpio_backlight.c | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/drivers/video/backlight/gpio_backlight.c b/drivers/video/backlight/gpio_backlight.c
index 20c5311c7ed2..6247687b6330 100644
--- a/drivers/video/backlight/gpio_backlight.c
+++ b/drivers/video/backlight/gpio_backlight.c
@@ -71,25 +71,25 @@ static int gpio_backlight_initial_power_state(struct gpio_backlight *gbl)
 
 static int gpio_backlight_probe(struct platform_device *pdev)
 {
-	struct gpio_backlight_platform_data *pdata =
-		dev_get_platdata(&pdev->dev);
+	struct device *dev = &pdev->dev;
+	struct gpio_backlight_platform_data *pdata = dev_get_platdata(dev);
 	struct backlight_properties props;
 	struct backlight_device *bl;
 	struct gpio_backlight *gbl;
 	int ret;
 
-	gbl = devm_kzalloc(&pdev->dev, sizeof(*gbl), GFP_KERNEL);
+	gbl = devm_kzalloc(dev, sizeof(*gbl), GFP_KERNEL);
 	if (gbl == NULL)
 		return -ENOMEM;
 
-	gbl->dev = &pdev->dev;
+	gbl->dev = dev;
 
 	if (pdata)
 		gbl->fbdev = pdata->fbdev;
 
-	gbl->def_value = device_property_read_bool(&pdev->dev, "default-on");
+	gbl->def_value = device_property_read_bool(dev, "default-on");
 
-	gbl->gpiod = devm_gpiod_get(&pdev->dev, NULL, GPIOD_ASIS);
+	gbl->gpiod = devm_gpiod_get(dev, NULL, GPIOD_ASIS);
 	if (IS_ERR(gbl->gpiod)) {
 		ret = PTR_ERR(gbl->gpiod);
 		if (ret != -EPROBE_DEFER)
@@ -101,11 +101,11 @@ static int gpio_backlight_probe(struct platform_device *pdev)
 	memset(&props, 0, sizeof(props));
 	props.type = BACKLIGHT_RAW;
 	props.max_brightness = 1;
-	bl = devm_backlight_device_register(&pdev->dev, dev_name(&pdev->dev),
-					&pdev->dev, gbl, &gpio_backlight_ops,
+	bl = devm_backlight_device_register(dev, dev_name(dev),
+					dev, gbl, &gpio_backlight_ops,
 					&props);
 	if (IS_ERR(bl)) {
-		dev_err(&pdev->dev, "failed to register backlight\n");
+		dev_err(dev, "failed to register backlight\n");
 		return PTR_ERR(bl);
 	}
 
-- 
2.23.0

[PATCH v4 7/7] backlight: gpio: pull gpio_backlight_initial_power_state() into probe

[Bartosz Golaszewski]

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 two
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/video/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 *bl)
@@ -53,41 +50,24 @@ static const struct backlight_ops gpio_backlight_ops = {
 	.check_fb	= gpio_backlight_check_fb,
 };
 
-static int gpio_backlight_initial_power_state(struct gpio_backlight *gbl)
-{
-	struct device_node *node = 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_POWERDOWN;
-
-	/* if the enable GPIO is disabled, do not enable the backlight */
-	if (gpiod_get_value_cansleep(gbl->gpiod) == 0)
-		return FB_BLANK_POWERDOWN;
-
-	return FB_BLANK_UNBLANK;
-}
-
-
 static int gpio_backlight_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
 	struct gpio_backlight_platform_data *pdata = dev_get_platdata(dev);
+	struct device_node *of_node = dev->of_node;
 	struct backlight_properties props;
 	struct backlight_device *bl;
 	struct gpio_backlight *gbl;
-	int ret;
+	int ret, def_value;
 
 	gbl = devm_kzalloc(dev, sizeof(*gbl), GFP_KERNEL);
 	if (gbl == NULL)
 		return -ENOMEM;
 
-	gbl->dev = dev;
-
 	if (pdata)
 		gbl->fbdev = pdata->fbdev;
 
-	gbl->def_value = device_property_read_bool(dev, "default-on");
+	def_value = device_property_read_bool(dev, "default-on");
 
 	gbl->gpiod = 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 = 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 = def_value ? FB_BLANK_UNBLANK
+					    : FB_BLANK_POWERDOWN;
+	else if (gpiod_get_value_cansleep(gbl->gpiod) == 0)
+		bl->props.power = FB_BLANK_POWERDOWN;
+	else
+		bl->props.power = FB_BLANK_UNBLANK;
+
 	bl->props.brightness = 1;
 
 	backlight_update_status(bl);
-- 
2.23.0

Re: [PATCH v4 7/7] backlight: gpio: pull gpio_backlight_initial_power_state() into probe

[Daniel Thompson]

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 two
> 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/video/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 *bl)
> @@ -53,41 +50,24 @@ static const struct backlight_ops gpio_backlight_ops = {
>  	.check_fb	= gpio_backlight_check_fb,
>  };
>  
> -static int gpio_backlight_initial_power_state(struct gpio_backlight *gbl)

I'm inclined to view deleting this function as removing a comment (e.g.
the function name helps us to read the code)!

Removing the variables from the context structure is good but why not
just pass them to the function and let the compiler decided whether or
not to inline.


Daniel.


> -{
> -	struct device_node *node = 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_POWERDOWN;
> -
> -	/* if the enable GPIO is disabled, do not enable the backlight */
> -	if (gpiod_get_value_cansleep(gbl->gpiod) == 0)
> -		return FB_BLANK_POWERDOWN;
> -
> -	return FB_BLANK_UNBLANK;
> -}
> -
> -
>  static int gpio_backlight_probe(struct platform_device *pdev)
>  {
>  	struct device *dev = &pdev->dev;
>  	struct gpio_backlight_platform_data *pdata = dev_get_platdata(dev);
> +	struct device_node *of_node = dev->of_node;
>  	struct backlight_properties props;
>  	struct backlight_device *bl;
>  	struct gpio_backlight *gbl;
> -	int ret;
> +	int ret, def_value;
>  
>  	gbl = devm_kzalloc(dev, sizeof(*gbl), GFP_KERNEL);
>  	if (gbl == NULL)
>  		return -ENOMEM;
>  
> -	gbl->dev = dev;
> -
>  	if (pdata)
>  		gbl->fbdev = pdata->fbdev;
>  
> -	gbl->def_value = device_property_read_bool(dev, "default-on");
> +	def_value = device_property_read_bool(dev, "default-on");
>  
>  	gbl->gpiod = 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 = 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 = def_value ? FB_BLANK_UNBLANK
> +					    : FB_BLANK_POWERDOWN;
> +	else if (gpiod_get_value_cansleep(gbl->gpiod) == 0)
> +		bl->props.power = FB_BLANK_POWERDOWN;
> +	else
> +		bl->props.power = FB_BLANK_UNBLANK;
> +
>  	bl->props.brightness = 1;
>  
>  	backlight_update_status(bl);
> -- 
> 2.23.0
> 

Re: [PATCH v4 7/7] backlight: gpio: pull gpio_backlight_initial_power_state() into probe

[Bartosz Golaszewski]

śr., 2 paź 2019 o 12:33 Daniel Thompson <daniel.thompson@linaro.org> napisał(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 two
> > 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/video/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 *bl)
> > @@ -53,41 +50,24 @@ static const struct backlight_ops gpio_backlight_ops = {
> >       .check_fb       = gpio_backlight_check_fb,
> >  };
> >
> > -static int gpio_backlight_initial_power_state(struct gpio_backlight *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? 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 or
> not to inline.
>
>
> Daniel.
>
>
> > -{
> > -     struct device_node *node = 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_POWERDOWN;
> > -
> > -     /* if the enable GPIO is disabled, do not enable the backlight */
> > -     if (gpiod_get_value_cansleep(gbl->gpiod) == 0)
> > -             return FB_BLANK_POWERDOWN;
> > -
> > -     return FB_BLANK_UNBLANK;
> > -}
> > -
> > -
> >  static int gpio_backlight_probe(struct platform_device *pdev)
> >  {
> >       struct device *dev = &pdev->dev;
> >       struct gpio_backlight_platform_data *pdata = dev_get_platdata(dev);
> > +     struct device_node *of_node = dev->of_node;
> >       struct backlight_properties props;
> >       struct backlight_device *bl;
> >       struct gpio_backlight *gbl;
> > -     int ret;
> > +     int ret, def_value;
> >
> >       gbl = devm_kzalloc(dev, sizeof(*gbl), GFP_KERNEL);
> >       if (gbl == NULL)
> >               return -ENOMEM;
> >
> > -     gbl->dev = dev;
> > -
> >       if (pdata)
> >               gbl->fbdev = pdata->fbdev;
> >
> > -     gbl->def_value = device_property_read_bool(dev, "default-on");
> > +     def_value = device_property_read_bool(dev, "default-on");
> >
> >       gbl->gpiod = 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 = 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 = def_value ? FB_BLANK_UNBLANK
> > +                                         : FB_BLANK_POWERDOWN;
> > +     else if (gpiod_get_value_cansleep(gbl->gpiod) == 0)
> > +             bl->props.power = FB_BLANK_POWERDOWN;
> > +     else
> > +             bl->props.power = FB_BLANK_UNBLANK;
> > +
> >       bl->props.brightness = 1;
> >
> >       backlight_update_status(bl);
> > --
> > 2.23.0
> >

Re: [PATCH v4 7/7] backlight: gpio: pull gpio_backlight_initial_power_state() into probe

[Daniel Thompson]

On Wed, Oct 02, 2019 at 01:46:17PM +0200, Bartosz Golaszewski wrote:
> śr., 2 paź 2019 o 12:33 Daniel Thompson <daniel.thompson@linaro.org> napisał(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 two
> > > 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/video/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 *bl)
> > > @@ -53,41 +50,24 @@ static const struct backlight_ops gpio_backlight_ops = {
> > >       .check_fb       = gpio_backlight_check_fb,
> > >  };
> > >
> > > -static int gpio_backlight_initial_power_state(struct gpio_backlight *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).


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 or
> > not to inline.
> >
> >
> > Daniel.
> >
> >
> > > -{
> > > -     struct device_node *node = 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_POWERDOWN;
> > > -
> > > -     /* if the enable GPIO is disabled, do not enable the backlight */
> > > -     if (gpiod_get_value_cansleep(gbl->gpiod) == 0)
> > > -             return FB_BLANK_POWERDOWN;
> > > -
> > > -     return FB_BLANK_UNBLANK;
> > > -}
> > > -
> > > -
> > >  static int gpio_backlight_probe(struct platform_device *pdev)
> > >  {
> > >       struct device *dev = &pdev->dev;
> > >       struct gpio_backlight_platform_data *pdata = dev_get_platdata(dev);
> > > +     struct device_node *of_node = dev->of_node;
> > >       struct backlight_properties props;
> > >       struct backlight_device *bl;
> > >       struct gpio_backlight *gbl;
> > > -     int ret;
> > > +     int ret, def_value;
> > >
> > >       gbl = devm_kzalloc(dev, sizeof(*gbl), GFP_KERNEL);
> > >       if (gbl == NULL)
> > >               return -ENOMEM;
> > >
> > > -     gbl->dev = dev;
> > > -
> > >       if (pdata)
> > >               gbl->fbdev = pdata->fbdev;
> > >
> > > -     gbl->def_value = device_property_read_bool(dev, "default-on");
> > > +     def_value = device_property_read_bool(dev, "default-on");
> > >
> > >       gbl->gpiod = 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 = 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 = def_value ? FB_BLANK_UNBLANK
> > > +                                         : FB_BLANK_POWERDOWN;
> > > +     else if (gpiod_get_value_cansleep(gbl->gpiod) == 0)
> > > +             bl->props.power = FB_BLANK_POWERDOWN;
> > > +     else
> > > +             bl->props.power = FB_BLANK_UNBLANK;
> > > +
> > >       bl->props.brightness = 1;
> > >
> > >       backlight_update_status(bl);
> > > --
> > > 2.23.0
> > >

Re: [PATCH v4 7/7] backlight: gpio: pull gpio_backlight_initial_power_state() into probe

[Bartosz Golaszewski]

śr., 2 paź 2019 o 16:40 Daniel Thompson <daniel.thompson@linaro.org> napisał(a):
>
> On Wed, Oct 02, 2019 at 01:46:17PM +0200, Bartosz Golaszewski wrote:
> > śr., 2 paź 2019 o 12:33 Daniel Thompson <daniel.thompson@linaro.org> napisał(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 two
> > > > 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/video/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 *bl)
> > > > @@ -53,41 +50,24 @@ static const struct backlight_ops gpio_backlight_ops = {
> > > >       .check_fb       = gpio_backlight_check_fb,
> > > >  };
> > > >
> > > > -static int gpio_backlight_initial_power_state(struct gpio_backlight *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 or
> > > not to inline.
> > >
> > >
> > > Daniel.
> > >
> > >
> > > > -{
> > > > -     struct device_node *node = 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_POWERDOWN;
> > > > -
> > > > -     /* if the enable GPIO is disabled, do not enable the backlight */
> > > > -     if (gpiod_get_value_cansleep(gbl->gpiod) == 0)
> > > > -             return FB_BLANK_POWERDOWN;
> > > > -
> > > > -     return FB_BLANK_UNBLANK;
> > > > -}
> > > > -
> > > > -
> > > >  static int gpio_backlight_probe(struct platform_device *pdev)
> > > >  {
> > > >       struct device *dev = &pdev->dev;
> > > >       struct gpio_backlight_platform_data *pdata = dev_get_platdata(dev);
> > > > +     struct device_node *of_node = dev->of_node;
> > > >       struct backlight_properties props;
> > > >       struct backlight_device *bl;
> > > >       struct gpio_backlight *gbl;
> > > > -     int ret;
> > > > +     int ret, def_value;
> > > >
> > > >       gbl = devm_kzalloc(dev, sizeof(*gbl), GFP_KERNEL);
> > > >       if (gbl == NULL)
> > > >               return -ENOMEM;
> > > >
> > > > -     gbl->dev = dev;
> > > > -
> > > >       if (pdata)
> > > >               gbl->fbdev = pdata->fbdev;
> > > >
> > > > -     gbl->def_value = device_property_read_bool(dev, "default-on");
> > > > +     def_value = device_property_read_bool(dev, "default-on");
> > > >
> > > >       gbl->gpiod = 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 = 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 = def_value ? FB_BLANK_UNBLANK
> > > > +                                         : FB_BLANK_POWERDOWN;
> > > > +     else if (gpiod_get_value_cansleep(gbl->gpiod) == 0)
> > > > +             bl->props.power = FB_BLANK_POWERDOWN;
> > > > +     else
> > > > +             bl->props.power = FB_BLANK_UNBLANK;
> > > > +
> > > >       bl->props.brightness = 1;
> > > >
> > > >       backlight_update_status(bl);
> > > > --
> > > > 2.23.0
> > > >