[PATCH v6 0/9] backlight: gpio: simplify the driver

[PATCH v6 0/9] 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.

First two patches contain minor fixes. Third patch makes the driver
explicitly drive the GPIO line. Fourth patch adds all necessary data
structures to ecovec24. Patch 5/9 unifies much of the code for both
pdata and non-pdata cases. Patches 6-7/9 remove unused platform data
fields. Last two 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

v4 -> v5:
- in patch 7/7: added a comment replacing the name of the function being
  pulled into probe()

v5 -> v6:
- added a patch making the driver explicitly set the direction of the GPIO
  to output
- added a patch removing a redundant newline

Bartosz Golaszewski (9):
  backlight: gpio: remove unneeded include
  backlight: gpio: remove stray newline
  backlight: gpio: explicitly set the direction of the GPIO
  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     | 128 +++++++------------
 include/linux/platform_data/gpio_backlight.h |   3 -
 3 files changed, 69 insertions(+), 95 deletions(-)

-- 
2.23.0

[PATCH v6 1/9] 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>
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 | 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

[PATCH v6 2/9] backlight: gpio: remove stray newline

[Bartosz Golaszewski]

From: Bartosz Golaszewski <bgolaszewski@baylibre.com>

Remove a double newline from the driver.

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 7e1990199fae..3955b513f2f8 100644
--- a/drivers/video/backlight/gpio_backlight.c
+++ b/drivers/video/backlight/gpio_backlight.c
@@ -91,7 +91,6 @@ static int gpio_backlight_initial_power_state(struct gpio_backlight *gbl)
 	return FB_BLANK_UNBLANK;
 }
 
-
 static int gpio_backlight_probe(struct platform_device *pdev)
 {
 	struct gpio_backlight_platform_data *pdata =
-- 
2.23.0

[PATCH v6 3/9] backlight: gpio: explicitly set the direction of the GPIO

[Bartosz Golaszewski]

From: Bartosz Golaszewski <bgolaszewski@baylibre.com>

The GPIO backlight driver currently requests the line 'as is', without
acively setting its direction. This can lead to problems: if the line
is in input mode by default, we won't be able to drive it later when
updating the status and also reading its initial value doesn't make
sense for backlight setting.

Request the line 'as is' initially, so that we can read its value
without affecting it but then change the direction to output explicitly
when setting the initial brightness.

Also: check the current direction and only read the value if it's output.

Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
---
 drivers/video/backlight/gpio_backlight.c | 23 ++++++++++++++++++-----
 1 file changed, 18 insertions(+), 5 deletions(-)

diff --git a/drivers/video/backlight/gpio_backlight.c b/drivers/video/backlight/gpio_backlight.c
index 3955b513f2f8..a36ac3a45b81 100644
--- a/drivers/video/backlight/gpio_backlight.c
+++ b/drivers/video/backlight/gpio_backlight.c
@@ -25,9 +25,8 @@ struct gpio_backlight {
 	int def_value;
 };
 
-static int gpio_backlight_update_status(struct backlight_device *bl)
+static int gpio_backlight_get_curr_brightness(struct backlight_device *bl)
 {
-	struct gpio_backlight *gbl = bl_get_data(bl);
 	int brightness = bl->props.brightness;
 
 	if (bl->props.power != FB_BLANK_UNBLANK ||
@@ -35,6 +34,14 @@ static int gpio_backlight_update_status(struct backlight_device *bl)
 	    bl->props.state & (BL_CORE_SUSPENDED | BL_CORE_FBBLANK))
 		brightness = 0;
 
+	return brightness;
+}
+
+static int gpio_backlight_update_status(struct backlight_device *bl)
+{
+	struct gpio_backlight *gbl = bl_get_data(bl);
+	int brightness = gpio_backlight_get_curr_brightness(bl);
+
 	gpiod_set_value_cansleep(gbl->gpiod, brightness);
 
 	return 0;
@@ -85,7 +92,8 @@ static int gpio_backlight_initial_power_state(struct gpio_backlight *gbl)
 		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)
+	if (gpiod_get_direction(gbl->gpiod) == 0 &&
+	    gpiod_get_value_cansleep(gbl->gpiod) == 0)
 		return FB_BLANK_POWERDOWN;
 
 	return FB_BLANK_UNBLANK;
@@ -98,7 +106,7 @@ static int gpio_backlight_probe(struct platform_device *pdev)
 	struct backlight_properties props;
 	struct backlight_device *bl;
 	struct gpio_backlight *gbl;
-	int ret;
+	int ret, init_brightness;
 
 	gbl = devm_kzalloc(&pdev->dev, sizeof(*gbl), GFP_KERNEL);
 	if (gbl == NULL)
@@ -151,7 +159,12 @@ static int gpio_backlight_probe(struct platform_device *pdev)
 	bl->props.power = gpio_backlight_initial_power_state(gbl);
 	bl->props.brightness = 1;
 
-	backlight_update_status(bl);
+	init_brightness = gpio_backlight_get_curr_brightness(bl);
+	ret = gpiod_direction_output(gbl->gpiod, init_brightness);
+	if (ret) {
+		dev_err(&pdev->dev, "failed to set initial brightness\n");
+		return ret;
+	}
 
 	platform_set_drvdata(pdev, bl);
 	return 0;
-- 
2.23.0

[PATCH v6 4/9] 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 v6 5/9] 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 a36ac3a45b81..c829b82f5372 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>
@@ -61,28 +60,6 @@ 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;
@@ -114,35 +91,18 @@ 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 v6 6/9] 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 v6 7/9] 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 v6 8/9] 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 | 23 +++++++++++------------
 1 file changed, 11 insertions(+), 12 deletions(-)

diff --git a/drivers/video/backlight/gpio_backlight.c b/drivers/video/backlight/gpio_backlight.c
index c829b82f5372..7b411f6ee15a 100644
--- a/drivers/video/backlight/gpio_backlight.c
+++ b/drivers/video/backlight/gpio_backlight.c
@@ -78,29 +78,29 @@ 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, init_brightness;
 
-	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)
-			dev_err(&pdev->dev,
+			dev_err(dev,
 				"Error: The gpios parameter is missing or invalid.\n");
 		return ret;
 	}
@@ -108,11 +108,10 @@ 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,
-					&props);
+	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);
 	}
 
@@ -122,7 +121,7 @@ static int gpio_backlight_probe(struct platform_device *pdev)
 	init_brightness = gpio_backlight_get_curr_brightness(bl);
 	ret = gpiod_direction_output(gbl->gpiod, init_brightness);
 	if (ret) {
-		dev_err(&pdev->dev, "failed to set initial brightness\n");
+		dev_err(dev, "failed to set initial brightness\n");
 		return ret;
 	}
 
-- 
2.23.0

[PATCH v6 9/9] 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>
Acked-by: Daniel Thompson <daniel.thompson@linaro.org>
---
 drivers/video/backlight/gpio_backlight.c | 38 +++++++++---------------
 1 file changed, 14 insertions(+), 24 deletions(-)

diff --git a/drivers/video/backlight/gpio_backlight.c b/drivers/video/backlight/gpio_backlight.c
index 7b411f6ee15a..4336db6bf6b5 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_get_curr_brightness(struct backlight_device *bl)
@@ -60,41 +57,24 @@ 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_direction(gbl->gpiod) == 0 &&
-	    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, init_brightness;
+	int ret, init_brightness, 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)) {
@@ -115,7 +95,17 @@ static int gpio_backlight_probe(struct platform_device *pdev)
 		return PTR_ERR(bl);
 	}
 
-	bl->props.power = gpio_backlight_initial_power_state(gbl);
+	/* Set the initial power state */
+	if (!of_node || !of_node->phandle)
+		/* Not booted with device tree or no phandle link to the node */
+		bl->props.power = def_value ? FB_BLANK_UNBLANK
+					    : FB_BLANK_POWERDOWN;
+	else if (gpiod_get_direction(gbl->gpiod) == 0 &&
+		 gpiod_get_value_cansleep(gbl->gpiod) == 0)
+		bl->props.power = FB_BLANK_POWERDOWN;
+	else
+		bl->props.power = FB_BLANK_UNBLANK;
+
 	bl->props.brightness = 1;
 
 	init_brightness = gpio_backlight_get_curr_brightness(bl);
-- 
2.23.0

Re: [PATCH v6 2/9] backlight: gpio: remove stray newline

[Andy Shevchenko]

On Sat, Oct 19, 2019 at 12:58 PM Bartosz Golaszewski <brgl@bgdev.pl> wrote:
>
> From: Bartosz Golaszewski <bgolaszewski@baylibre.com>
>
> Remove a double newline from the driver.
>

Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>

> 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 7e1990199fae..3955b513f2f8 100644
> --- a/drivers/video/backlight/gpio_backlight.c
> +++ b/drivers/video/backlight/gpio_backlight.c
> @@ -91,7 +91,6 @@ static int gpio_backlight_initial_power_state(struct gpio_backlight *gbl)
>         return FB_BLANK_UNBLANK;
>  }
>
> -
>  static int gpio_backlight_probe(struct platform_device *pdev)
>  {
>         struct gpio_backlight_platform_data *pdata =
> --
> 2.23.0
>


-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v6 2/9] backlight: gpio: remove stray newline

[Daniel Thompson]

On Sat, Oct 19, 2019 at 10:35:49AM +0200, Bartosz Golaszewski wrote:
> From: Bartosz Golaszewski <bgolaszewski@baylibre.com>
> 
> Remove a double newline from the driver.
> 
> Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>

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

(wow! that one was easy ;-) )

> ---
>  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 7e1990199fae..3955b513f2f8 100644
> --- a/drivers/video/backlight/gpio_backlight.c
> +++ b/drivers/video/backlight/gpio_backlight.c
> @@ -91,7 +91,6 @@ static int gpio_backlight_initial_power_state(struct gpio_backlight *gbl)
>  	return FB_BLANK_UNBLANK;
>  }
>  
> -
>  static int gpio_backlight_probe(struct platform_device *pdev)
>  {
>  	struct gpio_backlight_platform_data *pdata =
> -- 
> 2.23.0
> 

Re: [PATCH v6 3/9] backlight: gpio: explicitly set the direction of the GPIO

[Daniel Thompson]

On Sat, Oct 19, 2019 at 10:35:50AM +0200, Bartosz Golaszewski wrote:
> From: Bartosz Golaszewski <bgolaszewski@baylibre.com>
> 
> The GPIO backlight driver currently requests the line 'as is', without
> acively setting its direction. This can lead to problems: if the line
> is in input mode by default, we won't be able to drive it later when
> updating the status and also reading its initial value doesn't make
> sense for backlight setting.
> 
> Request the line 'as is' initially, so that we can read its value
> without affecting it but then change the direction to output explicitly
> when setting the initial brightness.
> 
> Also: check the current direction and only read the value if it's output.
> 
> Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>

Intent looks good to me but...

> ---
>  drivers/video/backlight/gpio_backlight.c | 23 ++++++++++++++++++-----
>  1 file changed, 18 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/video/backlight/gpio_backlight.c b/drivers/video/backlight/gpio_backlight.c
> index 3955b513f2f8..a36ac3a45b81 100644
> --- a/drivers/video/backlight/gpio_backlight.c
> +++ b/drivers/video/backlight/gpio_backlight.c
> @@ -25,9 +25,8 @@ struct gpio_backlight {
>  	int def_value;
>  };
>  
> -static int gpio_backlight_update_status(struct backlight_device *bl)
> +static int gpio_backlight_get_curr_brightness(struct backlight_device *bl)

This function does not get the current brightness (e.g. what the
hardware is currently doing). Given we've just nuked the function that 
*did* get the current brightness from the hardware this isn't an
acceptable name.

Would like something like calc_brightness() or get_next_brightness().


Daniel.

Re: [PATCH v6 3/9] backlight: gpio: explicitly set the direction of the GPIO

[Bartosz Golaszewski]

pon., 21 paź 2019 o 12:45 Daniel Thompson <daniel.thompson@linaro.org>
napisał(a):
>
> On Sat, Oct 19, 2019 at 10:35:50AM +0200, Bartosz Golaszewski wrote:
> > From: Bartosz Golaszewski <bgolaszewski@baylibre.com>
> >
> > The GPIO backlight driver currently requests the line 'as is', without
> > acively setting its direction. This can lead to problems: if the line
> > is in input mode by default, we won't be able to drive it later when
> > updating the status and also reading its initial value doesn't make
> > sense for backlight setting.
> >
> > Request the line 'as is' initially, so that we can read its value
> > without affecting it but then change the direction to output explicitly
> > when setting the initial brightness.
> >
> > Also: check the current direction and only read the value if it's output.
> >
> > Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
>
> Intent looks good to me but...
>
> > ---
> >  drivers/video/backlight/gpio_backlight.c | 23 ++++++++++++++++++-----
> >  1 file changed, 18 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/video/backlight/gpio_backlight.c b/drivers/video/backlight/gpio_backlight.c
> > index 3955b513f2f8..a36ac3a45b81 100644
> > --- a/drivers/video/backlight/gpio_backlight.c
> > +++ b/drivers/video/backlight/gpio_backlight.c
> > @@ -25,9 +25,8 @@ struct gpio_backlight {
> >       int def_value;
> >  };
> >
> > -static int gpio_backlight_update_status(struct backlight_device *bl)
> > +static int gpio_backlight_get_curr_brightness(struct backlight_device *bl)
>
> This function does not get the current brightness (e.g. what the
> hardware is currently doing). Given we've just nuked the function that
> *did* get the current brightness from the hardware this isn't an
> acceptable name.
>
> Would like something like calc_brightness() or get_next_brightness().
>

Fair enough, the latter sounds good in this case.

Bart