[PATCH v3 0/2] Add sgm3140 flash led driver

[PATCH v3 0/2] Add sgm3140 flash led driver

[Luca Weiss]

This series introduces a driver for the SGMICRO SGM3140 charge pump
used in the PinePhone smartphone.

Luca Weiss (2):
  dt-bindings: leds: Add binding for sgm3140
  leds: add sgm3140 driver

 .../bindings/leds/leds-sgm3140.yaml           |  62 ++++
 drivers/leds/Kconfig                          |   8 +
 drivers/leds/Makefile                         |   1 +
 drivers/leds/leds-sgm3140.c                   | 320 ++++++++++++++++++
 4 files changed, 391 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/leds/leds-sgm3140.yaml
 create mode 100644 drivers/leds/leds-sgm3140.c

-- 
2.26.1

[PATCH v3 1/2] dt-bindings: leds: Add binding for sgm3140

[Luca Weiss]

Add YAML devicetree binding for SGMICRO SGM3140 charge pump used for
camera flash LEDs.

Signed-off-by: Luca Weiss <luca@z3ntu.xyz>
Reviewed-by: Dan Murphy <dmurphy@ti.com>
Reviewed-by: Rob Herring <robh@kernel.org>
---
Changes since v2:
 - add 'type: object' to led property
 - rename dt node in example from sgm3140 to led-controller to match dt spec

 .../bindings/leds/leds-sgm3140.yaml           | 62 +++++++++++++++++++
 1 file changed, 62 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/leds/leds-sgm3140.yaml

diff --git a/Documentation/devicetree/bindings/leds/leds-sgm3140.yaml b/Documentation/devicetree/bindings/leds/leds-sgm3140.yaml
new file mode 100644
index 0000000000000..ecf7ac9ab0673
--- /dev/null
+++ b/Documentation/devicetree/bindings/leds/leds-sgm3140.yaml
@@ -0,0 +1,62 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/leds/leds-sgm3140.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: SGMICRO SGM3140 500mA Buck/Boost Charge Pump LED Driver
+
+maintainers:
+  - Luca Weiss <luca@z3ntu.xyz>
+
+description: |
+  The SGM3140 is a current-regulated charge pump which can regulate two current
+  levels for Flash and Torch modes.
+
+  The data sheet can be found at:
+    http://www.sg-micro.com/uploads/soft/20190626/1561535688.pdf
+
+properties:
+  compatible:
+    const: sgmicro,sgm3140
+
+  enable-gpios:
+    maxItems: 1
+    description: A connection to the 'EN' pin.
+
+  flash-gpios:
+    maxItems: 1
+    description: A connection to the 'FLASH' pin.
+
+  vin-supply:
+    description: Regulator providing power to the 'VIN' pin.
+
+  led:
+    type: object
+    allOf:
+      - $ref: common.yaml#
+
+required:
+  - compatible
+  - flash-gpios
+  - enable-gpios
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+    #include <dt-bindings/leds/common.h>
+
+    led-controller {
+        compatible = "sgmicro,sgm3140";
+        flash-gpios = <&pio 3 24 GPIO_ACTIVE_HIGH>; /* PD24 */
+        enable-gpios = <&pio 2 3 GPIO_ACTIVE_HIGH>; /* PC3 */
+        vin-supply = <&reg_dcdc1>;
+
+        sgm3140_flash: led {
+            function = LED_FUNCTION_FLASH;
+            color = <LED_COLOR_ID_WHITE>;
+            flash-max-timeout-us = <250000>;
+        };
+    };
-- 
2.26.1

[PATCH v3 2/2] leds: add sgm3140 driver

[Luca Weiss]

Add a driver for the SGMICRO SGM3140 Buck/Boost Charge Pump LED driver.

This device is controlled by two GPIO pins, one for enabling and the
second one for switching between torch and flash mode.

Signed-off-by: Luca Weiss <luca@z3ntu.xyz>
---
Changes since v2:
 - switch from of to fwnode API

 drivers/leds/Kconfig        |   8 +
 drivers/leds/Makefile       |   1 +
 drivers/leds/leds-sgm3140.c | 320 ++++++++++++++++++++++++++++++++++++
 3 files changed, 329 insertions(+)
 create mode 100644 drivers/leds/leds-sgm3140.c

diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
index 7599dbee8de13..e746c4429a288 100644
--- a/drivers/leds/Kconfig
+++ b/drivers/leds/Kconfig
@@ -871,6 +871,14 @@ config LEDS_IP30
 	  To compile this driver as a module, choose M here: the module
 	  will be called leds-ip30.
 
+config LEDS_SGM3140
+	tristate "LED support for the SGM3140"
+	depends on LEDS_CLASS_FLASH
+	depends on V4L2_FLASH_LED_CLASS || !V4L2_FLASH_LED_CLASS
+	help
+	  This option enables support for the SGM3140 500mA Buck/Boost Charge
+	  Pump LED Driver.
+
 comment "LED Triggers"
 source "drivers/leds/trigger/Kconfig"
 
diff --git a/drivers/leds/Makefile b/drivers/leds/Makefile
index fd61421f7d405..f60ed0c09d4c9 100644
--- a/drivers/leds/Makefile
+++ b/drivers/leds/Makefile
@@ -77,6 +77,7 @@ obj-$(CONFIG_LEDS_PWM)			+= leds-pwm.o
 obj-$(CONFIG_LEDS_REGULATOR)		+= leds-regulator.o
 obj-$(CONFIG_LEDS_S3C24XX)		+= leds-s3c24xx.o
 obj-$(CONFIG_LEDS_SC27XX_BLTC)		+= leds-sc27xx-bltc.o
+obj-$(CONFIG_LEDS_SGM3140)		+= leds-sgm3140.o
 obj-$(CONFIG_LEDS_SUNFIRE)		+= leds-sunfire.o
 obj-$(CONFIG_LEDS_SYSCON)		+= leds-syscon.o
 obj-$(CONFIG_LEDS_TCA6507)		+= leds-tca6507.o
diff --git a/drivers/leds/leds-sgm3140.c b/drivers/leds/leds-sgm3140.c
new file mode 100644
index 0000000000000..c494b934ae095
--- /dev/null
+++ b/drivers/leds/leds-sgm3140.c
@@ -0,0 +1,320 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2020 Luca Weiss <luca@z3ntu.xyz>
+
+#include <linux/gpio/consumer.h>
+#include <linux/led-class-flash.h>
+#include <linux/module.h>
+#include <linux/regulator/consumer.h>
+#include <linux/platform_device.h>
+
+#include <media/v4l2-flash-led-class.h>
+
+#define FLASH_TIMEOUT_DEFAULT		250000U /* 250ms */
+#define FLASH_MAX_TIMEOUT_DEFAULT	300000U /* 300ms */
+
+struct sgm3140 {
+	struct led_classdev_flash fled_cdev;
+	struct v4l2_flash *v4l2_flash;
+
+	struct timer_list powerdown_timer;
+
+	struct gpio_desc *flash_gpio;
+	struct gpio_desc *enable_gpio;
+	struct regulator *vin_regulator;
+
+	bool enabled;
+
+	/* current timeout in us */
+	u32 timeout;
+	/* maximum timeout in us */
+	u32 max_timeout;
+};
+
+static struct sgm3140 *flcdev_to_sgm3140(struct led_classdev_flash *flcdev)
+{
+	return container_of(flcdev, struct sgm3140, fled_cdev);
+}
+
+static int sgm3140_strobe_set(struct led_classdev_flash *fled_cdev, bool state)
+{
+	struct sgm3140 *priv = flcdev_to_sgm3140(fled_cdev);
+	int ret;
+
+	if (priv->enabled == state)
+		return 0;
+
+	if (state) {
+		ret = regulator_enable(priv->vin_regulator);
+		if (ret) {
+			dev_err(fled_cdev->led_cdev.dev,
+				"failed to enable regulator: %d\n", ret);
+			return ret;
+		}
+		gpiod_set_value_cansleep(priv->flash_gpio, 1);
+		gpiod_set_value_cansleep(priv->enable_gpio, 1);
+		mod_timer(&priv->powerdown_timer,
+			  jiffies + usecs_to_jiffies(priv->timeout));
+	} else {
+		del_timer_sync(&priv->powerdown_timer);
+		gpiod_set_value_cansleep(priv->enable_gpio, 0);
+		gpiod_set_value_cansleep(priv->flash_gpio, 0);
+		ret = regulator_disable(priv->vin_regulator);
+		if (ret) {
+			dev_err(fled_cdev->led_cdev.dev,
+				"failed to disable regulator: %d\n", ret);
+			return ret;
+		}
+	}
+
+	priv->enabled = state;
+
+	return 0;
+}
+
+static int sgm3140_strobe_get(struct led_classdev_flash *fled_cdev, bool *state)
+{
+	struct sgm3140 *priv = flcdev_to_sgm3140(fled_cdev);
+
+	*state = timer_pending(&priv->powerdown_timer);
+
+	return 0;
+}
+
+static int sgm3140_timeout_set(struct led_classdev_flash *fled_cdev,
+			       u32 timeout)
+{
+	struct sgm3140 *priv = flcdev_to_sgm3140(fled_cdev);
+
+	priv->timeout = timeout;
+
+	return 0;
+}
+
+static const struct led_flash_ops sgm3140_flash_ops = {
+	.strobe_set = sgm3140_strobe_set,
+	.strobe_get = sgm3140_strobe_get,
+	.timeout_set = sgm3140_timeout_set,
+};
+
+static int sgm3140_brightness_set(struct led_classdev *led_cdev,
+				  enum led_brightness brightness)
+{
+	struct led_classdev_flash *fled_cdev = lcdev_to_flcdev(led_cdev);
+	struct sgm3140 *priv = flcdev_to_sgm3140(fled_cdev);
+	bool enable = brightness == LED_ON;
+	int ret;
+
+	if (priv->enabled == enable)
+		return 0;
+
+	if (enable) {
+		ret = regulator_enable(priv->vin_regulator);
+		if (ret) {
+			dev_err(led_cdev->dev,
+				"failed to enable regulator: %d\n", ret);
+			return ret;
+		}
+		gpiod_set_value_cansleep(priv->enable_gpio, 1);
+	} else {
+		gpiod_set_value_cansleep(priv->enable_gpio, 0);
+		ret = regulator_disable(priv->vin_regulator);
+		if (ret) {
+			dev_err(led_cdev->dev,
+				"failed to disable regulator: %d\n", ret);
+			return ret;
+		}
+	}
+
+	priv->enabled = enable;
+
+	return 0;
+}
+
+static void sgm3140_powerdown_timer(struct timer_list *t)
+{
+	struct sgm3140 *priv = from_timer(priv, t, powerdown_timer);
+
+	gpiod_set_value(priv->enable_gpio, 0);
+	gpiod_set_value(priv->flash_gpio, 0);
+	regulator_disable(priv->vin_regulator);
+
+	priv->enabled = false;
+}
+
+static void sgm3140_init_flash_timeout(struct sgm3140 *priv)
+{
+	struct led_classdev_flash *fled_cdev = &priv->fled_cdev;
+	struct led_flash_setting *s;
+
+	/* Init flash timeout setting */
+	s = &fled_cdev->timeout;
+	s->min = 1;
+	s->max = priv->max_timeout;
+	s->step = 1;
+	s->val = FLASH_TIMEOUT_DEFAULT;
+}
+
+#if IS_ENABLED(CONFIG_V4L2_FLASH_LED_CLASS)
+static void sgm3140_init_v4l2_flash_config(struct sgm3140 *priv,
+					struct v4l2_flash_config *v4l2_sd_cfg)
+{
+	struct led_classdev *led_cdev = &priv->fled_cdev.led_cdev;
+	struct led_flash_setting *s;
+
+	strscpy(v4l2_sd_cfg->dev_name, led_cdev->dev->kobj.name,
+		sizeof(v4l2_sd_cfg->dev_name));
+
+	/* Init flash intensity setting */
+	s = &v4l2_sd_cfg->intensity;
+	s->min = 0;
+	s->max = 1;
+	s->step = 1;
+	s->val = 1;
+}
+
+#else
+static void sgm3140_init_v4l2_flash_config(struct sgm3140 *priv,
+					struct v4l2_flash_config *v4l2_sd_cfg)
+{
+}
+#endif
+
+static int sgm3140_probe(struct platform_device *pdev)
+{
+	struct sgm3140 *priv;
+	struct led_classdev *led_cdev;
+	struct led_classdev_flash *fled_cdev;
+	struct led_init_data init_data = {};
+	struct fwnode_handle *child_node;
+	struct v4l2_flash_config v4l2_sd_cfg = {};
+	int ret;
+
+	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	priv->flash_gpio = devm_gpiod_get(&pdev->dev, "flash", GPIOD_OUT_LOW);
+	ret = PTR_ERR_OR_ZERO(priv->flash_gpio);
+	if (ret) {
+		if (ret != -EPROBE_DEFER)
+			dev_err(&pdev->dev,
+				"Failed to request flash gpio: %d\n", ret);
+		return ret;
+	}
+
+	priv->enable_gpio = devm_gpiod_get(&pdev->dev, "enable", GPIOD_OUT_LOW);
+	ret = PTR_ERR_OR_ZERO(priv->enable_gpio);
+	if (ret) {
+		if (ret != -EPROBE_DEFER)
+			dev_err(&pdev->dev,
+				"Failed to request enable gpio: %d\n", ret);
+		return ret;
+	}
+
+	priv->vin_regulator = devm_regulator_get(&pdev->dev, "vin");
+	ret = PTR_ERR_OR_ZERO(priv->vin_regulator);
+	if (ret) {
+		if (ret != -EPROBE_DEFER)
+			dev_err(&pdev->dev,
+				"Failed to request regulator: %d\n", ret);
+		return ret;
+	}
+
+	child_node = fwnode_get_next_available_child_node(pdev->dev.fwnode,
+							  NULL);
+	if (!child_node) {
+		dev_err(&pdev->dev,
+			"No fwnode child node found for connected LED.\n");
+		return -EINVAL;
+	}
+
+	ret = fwnode_property_read_u32(child_node, "flash-max-timeout-us",
+				       &priv->max_timeout);
+	if (ret) {
+		priv->max_timeout = FLASH_MAX_TIMEOUT_DEFAULT;
+		dev_warn(&pdev->dev,
+			 "flash-max-timeout-us property missing\n");
+	}
+
+	/*
+	 * Set default timeout to FLASH_DEFAULT_TIMEOUT except if max_timeout
+	 * from DT is lower.
+	 */
+	priv->timeout = min(priv->max_timeout, FLASH_TIMEOUT_DEFAULT);
+
+	timer_setup(&priv->powerdown_timer, sgm3140_powerdown_timer, 0);
+
+	fled_cdev = &priv->fled_cdev;
+	led_cdev = &fled_cdev->led_cdev;
+
+	fled_cdev->ops = &sgm3140_flash_ops;
+
+	led_cdev->brightness_set_blocking = sgm3140_brightness_set;
+	led_cdev->max_brightness = LED_ON;
+	led_cdev->flags |= LED_DEV_CAP_FLASH;
+
+	sgm3140_init_flash_timeout(priv);
+
+	init_data.fwnode = child_node;
+
+	platform_set_drvdata(pdev, priv);
+
+	/* Register in the LED subsystem */
+	ret = devm_led_classdev_flash_register_ext(&pdev->dev,
+						   fled_cdev, &init_data);
+	if (ret) {
+		dev_err(&pdev->dev, "Failed to register flash device: %d\n",
+			ret);
+		goto err;
+	}
+
+	sgm3140_init_v4l2_flash_config(priv, &v4l2_sd_cfg);
+
+	/* Create V4L2 Flash subdev */
+	priv->v4l2_flash = v4l2_flash_init(&pdev->dev,
+					   child_node,
+					   fled_cdev, NULL,
+					   &v4l2_sd_cfg);
+	if (IS_ERR(priv->v4l2_flash)) {
+		ret = PTR_ERR(priv->v4l2_flash);
+		goto err;
+	}
+
+	return ret;
+
+err:
+	fwnode_handle_put(child_node);
+	return ret;
+}
+
+static int sgm3140_remove(struct platform_device *pdev)
+{
+	struct sgm3140 *priv = platform_get_drvdata(pdev);
+
+	del_timer_sync(&priv->powerdown_timer);
+
+	v4l2_flash_release(priv->v4l2_flash);
+
+	return 0;
+}
+
+static const struct of_device_id sgm3140_dt_match[] = {
+	{ .compatible = "sgmicro,sgm3140" },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, sgm3140_dt_match);
+
+static struct platform_driver sgm3140_driver = {
+	.probe	= sgm3140_probe,
+	.remove	= sgm3140_remove,
+	.driver	= {
+		.name	= "sgm3140",
+		.of_match_table = sgm3140_dt_match,
+	},
+};
+
+module_platform_driver(sgm3140_driver);
+
+MODULE_AUTHOR("Luca Weiss <luca@z3ntu.xyz>");
+MODULE_DESCRIPTION("SG Micro SGM3140 charge pump led driver");
+MODULE_LICENSE("GPL v2");
-- 
2.26.1

Re: [PATCH v3 2/2] leds: add sgm3140 driver

[Pavel Machek]

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Hi!

> Add a driver for the SGMICRO SGM3140 Buck/Boost Charge Pump LED driver.
> 
> This device is controlled by two GPIO pins, one for enabling and the
> second one for switching between torch and flash mode.
> 
> Signed-off-by: Luca Weiss <luca@z3ntu.xyz>

Thanks, applied, but... I may remove it again.

> +++ b/drivers/leds/leds-sgm3140.c
> @@ -0,0 +1,320 @@
> +// SPDX-License-Identifier: GPL-2.0

Would you consider GPL-2+?

> +#if IS_ENABLED(CONFIG_V4L2_FLASH_LED_CLASS)
> +static void sgm3140_init_v4l2_flash_config(struct sgm3140 *priv,

Ok.

> +static int sgm3140_probe(struct platform_device *pdev)
> +{
...
> +	led_cdev->brightness_set_blocking = sgm3140_brightness_set;
> +	led_cdev->max_brightness = LED_ON;

Don't do this, unless you really have 255 levels of brightness.

> +	/* Create V4L2 Flash subdev */
> +	priv->v4l2_flash = v4l2_flash_init(&pdev->dev,
> +					   child_node,
> +					   fled_cdev, NULL,
> +					   &v4l2_sd_cfg);
> +	if (IS_ERR(priv->v4l2_flash)) {

Does this need some #ifdef guards?

> +		ret = PTR_ERR(priv->v4l2_flash);
> +		goto err;
> +	}
> +
> +	return ret;

Should this return 0?

> +err:
> +	fwnode_handle_put(child_node);
> +	return ret;
> +}

Does non-error path needs handle_put, too?

Best regards,
									Pavel

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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Re: [PATCH v3 2/2] leds: add sgm3140 driver

[Luca Weiss]

[-- Attachment #1: Type: text/plain, Size: 2117 bytes --]

On Montag, 27. April 2020 11:51:02 CEST Pavel Machek wrote:
> Hi!
> 
> > Add a driver for the SGMICRO SGM3140 Buck/Boost Charge Pump LED driver.
> > 
> > This device is controlled by two GPIO pins, one for enabling and the
> > second one for switching between torch and flash mode.
> > 
> > Signed-off-by: Luca Weiss <luca@z3ntu.xyz>
> 
> Thanks, applied, but... I may remove it again.
> 
> > +++ b/drivers/leds/leds-sgm3140.c
> > @@ -0,0 +1,320 @@
> > +// SPDX-License-Identifier: GPL-2.0
> 
> Would you consider GPL-2+?

I don't really have a preference either way but GPL-2.0-or-later is fine for 
me.

> 
> > +#if IS_ENABLED(CONFIG_V4L2_FLASH_LED_CLASS)
> > +static void sgm3140_init_v4l2_flash_config(struct sgm3140 *priv,
> 
> Ok.
> 
> > +static int sgm3140_probe(struct platform_device *pdev)
> > +{
> 
> ...
> 
> > +	led_cdev->brightness_set_blocking = sgm3140_brightness_set;
> > +	led_cdev->max_brightness = LED_ON;
> 
> Don't do this, unless you really have 255 levels of brightness.

LED_ON is 1, so the brightness available is 0 - 1.

> 
> > +	/* Create V4L2 Flash subdev */
> > +	priv->v4l2_flash = v4l2_flash_init(&pdev->dev,
> > +					   child_node,
> > +					   fled_cdev, NULL,
> > +					   &v4l2_sd_cfg);
> > +	if (IS_ERR(priv->v4l2_flash)) {
> 
> Does this need some #ifdef guards?

v4l2_flash_init has a NULL-returning version when CONFIG_V4L2_FLASH_LED_CLASS 
is not defined (see https://elixir.bootlin.com/linux/latest/source/include/
media/v4l2-flash-led-class.h#L166 )

> 
> > +		ret = PTR_ERR(priv->v4l2_flash);
> > +		goto err;
> > +	}
> > +
> > +	return ret;
> 
> Should this return 0?

ret should be 0 here, so it shouldn't matter much.

> 
> > +err:
> > +	fwnode_handle_put(child_node);
> > +	return ret;
> > +}
> 
> Does non-error path needs handle_put, too?

I don't think so, I'm passing child_node to v4l2_flash_init which then saves 
the pointer to v4l2_subdev->fwnode. 

The devm_led_classdev_flash_register_ext function also seems to store the 
pointer (led_cdev->dev->fwnode = init_data->fwnode; in 
led_classdev_register_ext)

> 
> Best regards,
> 								
	Pavel

Regards,
Luca

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Re: [PATCH v3 2/2] leds: add sgm3140 driver

[Jacek Anaszewski]

Hi Luca,

On 4/27/20 9:49 PM, Luca Weiss wrote:
> On Montag, 27. April 2020 11:51:02 CEST Pavel Machek wrote:
>> Hi!
>>
>>> Add a driver for the SGMICRO SGM3140 Buck/Boost Charge Pump LED driver.
>>>
>>> This device is controlled by two GPIO pins, one for enabling and the
>>> second one for switching between torch and flash mode.
>>>
>>> Signed-off-by: Luca Weiss <luca@z3ntu.xyz>
>>
>> Thanks, applied, but... I may remove it again.
>>
>>> +++ b/drivers/leds/leds-sgm3140.c
>>> @@ -0,0 +1,320 @@
>>> +// SPDX-License-Identifier: GPL-2.0
>>
>> Would you consider GPL-2+?
> 
> I don't really have a preference either way but GPL-2.0-or-later is fine for
> me.
> 
>>
>>> +#if IS_ENABLED(CONFIG_V4L2_FLASH_LED_CLASS)
>>> +static void sgm3140_init_v4l2_flash_config(struct sgm3140 *priv,
>>
>> Ok.
>>
>>> +static int sgm3140_probe(struct platform_device *pdev)
>>> +{
>>
>> ...
>>
>>> +	led_cdev->brightness_set_blocking = sgm3140_brightness_set;
>>> +	led_cdev->max_brightness = LED_ON;
>>
>> Don't do this, unless you really have 255 levels of brightness.
> 
> LED_ON is 1, so the brightness available is 0 - 1.
> 
>>
>>> +	/* Create V4L2 Flash subdev */
>>> +	priv->v4l2_flash = v4l2_flash_init(&pdev->dev,
>>> +					   child_node,
>>> +					   fled_cdev, NULL,
>>> +					   &v4l2_sd_cfg);
>>> +	if (IS_ERR(priv->v4l2_flash)) {
>>
>> Does this need some #ifdef guards?
> 
> v4l2_flash_init has a NULL-returning version when CONFIG_V4L2_FLASH_LED_CLASS
> is not defined (see https://elixir.bootlin.com/linux/latest/source/include/
> media/v4l2-flash-led-class.h#L166 )

Correct.

>>
>>> +		ret = PTR_ERR(priv->v4l2_flash);
>>> +		goto err;
>>> +	}
>>> +
>>> +	return ret;
>>
>> Should this return 0?
> 
> ret should be 0 here, so it shouldn't matter much.
> 
>>
>>> +err:
>>> +	fwnode_handle_put(child_node);
>>> +	return ret;
>>> +}
>>
>> Does non-error path needs handle_put, too?
> 
> I don't think so, I'm passing child_node to v4l2_flash_init which then saves
> the pointer to v4l2_subdev->fwnode.
> 
> The devm_led_classdev_flash_register_ext function also seems to store the
> pointer (led_cdev->dev->fwnode = init_data->fwnode; in
> led_classdev_register_ext)

The node needs to be held only during parsing, so you
have to call fwnode_handle_put() for both paths.

-- 
Best regards,
Jacek Anaszewski