[v6,10/10] leds: aat1290: add support for V4L2 Flash sub-device

  Add support for V4L2 Flash sub-device to the aat1290 LED Flash class
driver. The support allows for V4L2 Flash sub-device to take the control
of the LED Flash class device.

Signed-off-by: Jacek Anaszewski <j.anaszewski@samsung.com>
Acked-by: Kyungmin Park <kyungmin.park@samsung.com>
Cc: Bryan Wu <cooloney@gmail.com>
Cc: Richard Purdie <rpurdie@rpsys.net>
Cc: Sakari Ailus <sakari.ailus@iki.fi>
---
 drivers/leds/Kconfig        |    1 +
 drivers/leds/leds-aat1290.c |  137 +++++++++++++++++++++++++++++++++++++++++--
 2 files changed, 132 insertions(+), 6 deletions(-)
  

Hi Jacek,

On Tue, Apr 28, 2015 at 09:18:50AM +0200, Jacek Anaszewski wrote:
> Add support for V4L2 Flash sub-device to the aat1290 LED Flash class
> driver. The support allows for V4L2 Flash sub-device to take the control
> of the LED Flash class device.
> 
> Signed-off-by: Jacek Anaszewski <j.anaszewski@samsung.com>
> Acked-by: Kyungmin Park <kyungmin.park@samsung.com>
> Cc: Bryan Wu <cooloney@gmail.com>
> Cc: Richard Purdie <rpurdie@rpsys.net>
> Cc: Sakari Ailus <sakari.ailus@iki.fi>
> ---
>  drivers/leds/Kconfig        |    1 +
>  drivers/leds/leds-aat1290.c |  137 +++++++++++++++++++++++++++++++++++++++++--
>  2 files changed, 132 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
> index dd7834c..874df63 100644
> --- a/drivers/leds/Kconfig
> +++ b/drivers/leds/Kconfig
> @@ -47,6 +47,7 @@ config LEDS_AAT1290
>  	depends on LEDS_CLASS_FLASH
>  	depends on GPIOLIB
>  	depends on OF
> +	depends on PINCTRL
>  	help
>  	 This option enables support for the LEDs on the AAT1290.
>  
> diff --git a/drivers/leds/leds-aat1290.c b/drivers/leds/leds-aat1290.c
> index 03e5b96..f37f848 100644
> --- a/drivers/leds/leds-aat1290.c
> +++ b/drivers/leds/leds-aat1290.c
> @@ -17,9 +17,11 @@
>  #include <linux/module.h>
>  #include <linux/mutex.h>
>  #include <linux/of.h>
> +#include <linux/pinctrl/consumer.h>
>  #include <linux/platform_device.h>
>  #include <linux/slab.h>
>  #include <linux/workqueue.h>
> +#include <media/v4l2-flash-led-class.h>
>  
>  #define AAT1290_MOVIE_MODE_CURRENT_ADDR	17
>  #define AAT1290_MAX_MM_CURR_PERCENT_0	16
> @@ -52,6 +54,8 @@ struct aat1290_led_config_data {
>  	u32 max_flash_current;
>  	/* maximum flash timeout */
>  	u32 max_flash_tm;
> +	/* external strobe capability */
> +	bool has_external_strobe;
>  	/* max LED brightness level */
>  	enum led_brightness max_brightness;
>  };
> @@ -64,6 +68,8 @@ struct aat1290_led {
>  
>  	/* corresponding LED Flash class device */
>  	struct led_classdev_flash fled_cdev;
> +	/* V4L2 Flash device */
> +	struct v4l2_flash *v4l2_flash;
>  
>  	/* FLEN pin */
>  	struct gpio_desc *gpio_fl_en;
> @@ -230,11 +236,15 @@ static int aat1290_led_flash_timeout_set(struct led_classdev_flash *fled_cdev,
>  }
>  
>  static int aat1290_led_parse_dt(struct aat1290_led *led,
> -			struct aat1290_led_config_data *cfg)
> +			struct aat1290_led_config_data *cfg,
> +			struct device_node **sub_node)
>  {
>  	struct led_classdev *led_cdev = &led->fled_cdev.led_cdev;
>  	struct device *dev = &led->pdev->dev;
>  	struct device_node *child_node;
> +#if IS_ENABLED(CONFIG_V4L2_FLASH_LED_CLASS)
> +	struct pinctrl *pinctrl;
> +#endif
>  	int ret = 0;
>  
>  	led->gpio_fl_en = devm_gpiod_get(dev, "flen");
> @@ -251,6 +261,17 @@ static int aat1290_led_parse_dt(struct aat1290_led *led,
>  		return ret;
>  	}
>  
> +#if IS_ENABLED(CONFIG_V4L2_FLASH_LED_CLASS)
> +	pinctrl = devm_pinctrl_get_select_default(&led->pdev->dev);
> +	if (IS_ERR(pinctrl)) {
> +		cfg->has_external_strobe = false;
> +		dev_info(dev,
> +			 "No support for external strobe detected.\n");
> +	} else {
> +		cfg->has_external_strobe = true;
> +	}
> +#endif
> +
>  	child_node = of_get_next_available_child(dev->of_node, NULL);
>  	if (!child_node) {
>  		dev_err(dev, "No DT child node found for connected LED.\n");
> @@ -288,6 +309,8 @@ static int aat1290_led_parse_dt(struct aat1290_led *led,
>  
>  	of_node_put(child_node);
>  
> +	*sub_node = child_node;
> +
>  	return ret;
>  }
>  
> @@ -316,7 +339,8 @@ int init_mm_current_scale(struct aat1290_led *led,
>  	int i, max_mm_current =
>  			AAT1290_MAX_MM_CURRENT(cfg->max_flash_current);
>  
> -	led->mm_current_scale = kzalloc(sizeof(max_mm_current_percent),
> +	led->mm_current_scale = devm_kzalloc(&led->pdev->dev,
> +					sizeof(max_mm_current_percent),
>  					GFP_KERNEL);
>  	if (!led->mm_current_scale)
>  		return -ENOMEM;
> @@ -329,11 +353,12 @@ int init_mm_current_scale(struct aat1290_led *led,
>  }
>  
>  static int aat1290_led_get_configuration(struct aat1290_led *led,
> -					struct aat1290_led_config_data *cfg)
> +					struct aat1290_led_config_data *cfg,
> +					struct device_node **sub_node)
>  {
>  	int ret;
>  
> -	ret = aat1290_led_parse_dt(led, cfg);
> +	ret = aat1290_led_parse_dt(led, cfg, sub_node);
>  	if (ret < 0)
>  		return ret;
>  	/*
> @@ -346,7 +371,10 @@ static int aat1290_led_get_configuration(struct aat1290_led *led,
>  
>  	aat1290_led_validate_mm_current(led, cfg);
>  
> -	kfree(led->mm_current_scale);
> +#if IS_ENABLED(CONFIG_V4L2_FLASH_LED_CLASS)
> +#else
> +	devm_kfree(&led->pdev->dev, led->mm_current_scale);
> +#endif
>  
>  	return 0;
>  }
> @@ -365,6 +393,83 @@ static void aat1290_init_flash_timeout(struct aat1290_led *led,
>  	setting->val = setting->max;
>  }
>  
> +#if IS_ENABLED(CONFIG_V4L2_FLASH_LED_CLASS)
> +enum led_brightness aat1290_intensity_to_brightness(
> +					struct v4l2_flash *v4l2_flash,
> +					s32 intensity)
> +{
> +	struct led_classdev_flash *fled_cdev = v4l2_flash->fled_cdev;
> +	struct aat1290_led *led = fled_cdev_to_led(fled_cdev);
> +	int i;
> +
> +	for (i = AAT1290_MM_CURRENT_SCALE_SIZE - 1; i >= 0; --i)
> +		if (intensity >= led->mm_current_scale[i])
> +			return i + 1;
> +
> +	return 1;
> +}
> +
> +s32 aat1290_brightness_to_intensity(struct v4l2_flash *v4l2_flash,
> +					enum led_brightness brightness)
> +{
> +	struct led_classdev_flash *fled_cdev = v4l2_flash->fled_cdev;
> +	struct aat1290_led *led = fled_cdev_to_led(fled_cdev);
> +
> +	return led->mm_current_scale[brightness - 1];
> +}
> +
> +static int aat1290_led_external_strobe_set(struct v4l2_flash *v4l2_flash,
> +						bool enable)
> +{
> +	struct aat1290_led *led = fled_cdev_to_led(v4l2_flash->fled_cdev);
> +	struct led_classdev_flash *fled_cdev = v4l2_flash->fled_cdev;
> +	struct led_classdev *led_cdev = &fled_cdev->led_cdev;
> +	struct pinctrl *pinctrl;
> +
> +	gpiod_direction_output(led->gpio_fl_en, 0);
> +	gpiod_direction_output(led->gpio_en_set, 0);
> +
> +	led->movie_mode = false;
> +	led_cdev->brightness = 0;
> +
> +	pinctrl = devm_pinctrl_get_select(&led->pdev->dev,
> +						enable ? "isp" : "host");
> +	if (IS_ERR(pinctrl)) {
> +		dev_warn(&led->pdev->dev, "Unable to switch strobe source.\n");
> +		return PTR_ERR(pinctrl);
> +	}
> +
> +	return 0;
> +}
> +
> +static void aat1290_init_v4l2_flash_config(struct aat1290_led *led,
> +					struct aat1290_led_config_data *led_cfg,
> +					struct v4l2_flash_config *v4l2_sd_cfg)
> +{
> +	struct led_classdev *led_cdev = &led->fled_cdev.led_cdev;
> +	struct led_flash_setting *s;
> +
> +	strlcpy(v4l2_sd_cfg->dev_name, led_cdev->name,
> +		sizeof(v4l2_sd_cfg->dev_name));
> +
> +	s = &v4l2_sd_cfg->intensity;
> +	s->min = led->mm_current_scale[0];
> +	s->max = led_cfg->max_mm_current;
> +	s->step = 1;
> +	s->val = s->max;
> +
> +	v4l2_sd_cfg->has_external_strobe = led_cfg->has_external_strobe;
> +}
> +
> +static const struct v4l2_flash_ops v4l2_flash_ops = {
> +	.external_strobe_set = aat1290_led_external_strobe_set,
> +	.intensity_to_led_brightness = aat1290_intensity_to_brightness,
> +	.led_brightness_to_intensity = aat1290_brightness_to_intensity,
> +};
> +#else
> +#define aat1290_init_v4l2_flash_config(led, led_cfg, v4l2_sd_cfg)
> +#endif
> +
>  static const struct led_flash_ops flash_ops = {
>  	.strobe_set = aat1290_led_flash_strobe_set,
>  	.timeout_set = aat1290_led_flash_timeout_set,
> @@ -373,10 +478,14 @@ static const struct led_flash_ops flash_ops = {
>  static int aat1290_led_probe(struct platform_device *pdev)
>  {
>  	struct device *dev = &pdev->dev;
> +	struct device_node *sub_node = NULL;
>  	struct aat1290_led *led;
>  	struct led_classdev *led_cdev;
>  	struct led_classdev_flash *fled_cdev;
>  	struct aat1290_led_config_data led_cfg = {};
> +#if IS_ENABLED(CONFIG_V4L2_FLASH_LED_CLASS)
> +	struct v4l2_flash_config v4l2_sd_cfg = {};
> +#endif
>  	int ret;
>  
>  	led = devm_kzalloc(dev, sizeof(*led), GFP_KERNEL);
> @@ -390,7 +499,7 @@ static int aat1290_led_probe(struct platform_device *pdev)
>  	fled_cdev->ops = &flash_ops;
>  	led_cdev = &fled_cdev->led_cdev;
>  
> -	ret = aat1290_led_get_configuration(led, &led_cfg);
> +	ret = aat1290_led_get_configuration(led, &led_cfg, &sub_node);
>  	if (ret < 0)
>  		return ret;
>  
> @@ -410,8 +519,23 @@ static int aat1290_led_probe(struct platform_device *pdev)
>  	if (ret < 0)
>  		goto err_flash_register;
>  
> +	aat1290_init_v4l2_flash_config(led, &led_cfg, &v4l2_sd_cfg);
> +
> +	led_cdev->dev->of_node = sub_node;

What's the reason for this? I can't immediately see how this is being used.

There's also a problem with references, you should grab it here and release
when it's no longer used.

> +
> +	/* Create V4L2 Flash subdev. */
> +	led->v4l2_flash = v4l2_flash_init(fled_cdev,
> +					  &v4l2_flash_ops,
> +					  &v4l2_sd_cfg);
> +	if (IS_ERR(led->v4l2_flash)) {
> +		ret = PTR_ERR(led->v4l2_flash);
> +		goto error_v4l2_flash_init;
> +	}
> +
>  	return 0;
>  
> +error_v4l2_flash_init:
> +	led_classdev_flash_unregister(fled_cdev);
>  err_flash_register:
>  	mutex_destroy(&led->lock);
>  
> @@ -422,6 +546,7 @@ static int aat1290_led_remove(struct platform_device *pdev)
>  {
>  	struct aat1290_led *led = platform_get_drvdata(pdev);
>  
> +	v4l2_flash_release(led->v4l2_flash);
>  	led_classdev_flash_unregister(&led->fled_cdev);
>  	cancel_work_sync(&led->work_brightness_set);
>
  

Hi Sakari,

On 04/28/2015 04:02 PM, Sakari Ailus wrote:
> Hi Jacek,
>
> On Tue, Apr 28, 2015 at 09:18:50AM +0200, Jacek Anaszewski wrote:
>> Add support for V4L2 Flash sub-device to the aat1290 LED Flash class
>> driver. The support allows for V4L2 Flash sub-device to take the control
>> of the LED Flash class device.
>>
>> Signed-off-by: Jacek Anaszewski <j.anaszewski@samsung.com>
>> Acked-by: Kyungmin Park <kyungmin.park@samsung.com>
>> Cc: Bryan Wu <cooloney@gmail.com>
>> Cc: Richard Purdie <rpurdie@rpsys.net>
>> Cc: Sakari Ailus <sakari.ailus@iki.fi>
>> ---
>>   drivers/leds/Kconfig        |    1 +
>>   drivers/leds/leds-aat1290.c |  137 +++++++++++++++++++++++++++++++++++++++++--
>>   2 files changed, 132 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
>> index dd7834c..874df63 100644
>> --- a/drivers/leds/Kconfig
>> +++ b/drivers/leds/Kconfig
>> @@ -47,6 +47,7 @@ config LEDS_AAT1290
>>   	depends on LEDS_CLASS_FLASH
>>   	depends on GPIOLIB
>>   	depends on OF
>> +	depends on PINCTRL
>>   	help
>>   	 This option enables support for the LEDs on the AAT1290.
>>
>> diff --git a/drivers/leds/leds-aat1290.c b/drivers/leds/leds-aat1290.c
>> index 03e5b96..f37f848 100644
>> --- a/drivers/leds/leds-aat1290.c
>> +++ b/drivers/leds/leds-aat1290.c
>> @@ -17,9 +17,11 @@
>>   #include <linux/module.h>
>>   #include <linux/mutex.h>
>>   #include <linux/of.h>
>> +#include <linux/pinctrl/consumer.h>
>>   #include <linux/platform_device.h>
>>   #include <linux/slab.h>
>>   #include <linux/workqueue.h>
>> +#include <media/v4l2-flash-led-class.h>
>>
>>   #define AAT1290_MOVIE_MODE_CURRENT_ADDR	17
>>   #define AAT1290_MAX_MM_CURR_PERCENT_0	16
>> @@ -52,6 +54,8 @@ struct aat1290_led_config_data {
>>   	u32 max_flash_current;
>>   	/* maximum flash timeout */
>>   	u32 max_flash_tm;
>> +	/* external strobe capability */
>> +	bool has_external_strobe;
>>   	/* max LED brightness level */
>>   	enum led_brightness max_brightness;
>>   };
>> @@ -64,6 +68,8 @@ struct aat1290_led {
>>
>>   	/* corresponding LED Flash class device */
>>   	struct led_classdev_flash fled_cdev;
>> +	/* V4L2 Flash device */
>> +	struct v4l2_flash *v4l2_flash;
>>
>>   	/* FLEN pin */
>>   	struct gpio_desc *gpio_fl_en;
>> @@ -230,11 +236,15 @@ static int aat1290_led_flash_timeout_set(struct led_classdev_flash *fled_cdev,
>>   }
>>
>>   static int aat1290_led_parse_dt(struct aat1290_led *led,
>> -			struct aat1290_led_config_data *cfg)
>> +			struct aat1290_led_config_data *cfg,
>> +			struct device_node **sub_node)
>>   {
>>   	struct led_classdev *led_cdev = &led->fled_cdev.led_cdev;
>>   	struct device *dev = &led->pdev->dev;
>>   	struct device_node *child_node;
>> +#if IS_ENABLED(CONFIG_V4L2_FLASH_LED_CLASS)
>> +	struct pinctrl *pinctrl;
>> +#endif
>>   	int ret = 0;
>>
>>   	led->gpio_fl_en = devm_gpiod_get(dev, "flen");
>> @@ -251,6 +261,17 @@ static int aat1290_led_parse_dt(struct aat1290_led *led,
>>   		return ret;
>>   	}
>>
>> +#if IS_ENABLED(CONFIG_V4L2_FLASH_LED_CLASS)
>> +	pinctrl = devm_pinctrl_get_select_default(&led->pdev->dev);
>> +	if (IS_ERR(pinctrl)) {
>> +		cfg->has_external_strobe = false;
>> +		dev_info(dev,
>> +			 "No support for external strobe detected.\n");
>> +	} else {
>> +		cfg->has_external_strobe = true;
>> +	}
>> +#endif
>> +
>>   	child_node = of_get_next_available_child(dev->of_node, NULL);
>>   	if (!child_node) {
>>   		dev_err(dev, "No DT child node found for connected LED.\n");
>> @@ -288,6 +309,8 @@ static int aat1290_led_parse_dt(struct aat1290_led *led,
>>
>>   	of_node_put(child_node);
>>
>> +	*sub_node = child_node;
>> +
>>   	return ret;
>>   }
>>
>> @@ -316,7 +339,8 @@ int init_mm_current_scale(struct aat1290_led *led,
>>   	int i, max_mm_current =
>>   			AAT1290_MAX_MM_CURRENT(cfg->max_flash_current);
>>
>> -	led->mm_current_scale = kzalloc(sizeof(max_mm_current_percent),
>> +	led->mm_current_scale = devm_kzalloc(&led->pdev->dev,
>> +					sizeof(max_mm_current_percent),
>>   					GFP_KERNEL);
>>   	if (!led->mm_current_scale)
>>   		return -ENOMEM;
>> @@ -329,11 +353,12 @@ int init_mm_current_scale(struct aat1290_led *led,
>>   }
>>
>>   static int aat1290_led_get_configuration(struct aat1290_led *led,
>> -					struct aat1290_led_config_data *cfg)
>> +					struct aat1290_led_config_data *cfg,
>> +					struct device_node **sub_node)
>>   {
>>   	int ret;
>>
>> -	ret = aat1290_led_parse_dt(led, cfg);
>> +	ret = aat1290_led_parse_dt(led, cfg, sub_node);
>>   	if (ret < 0)
>>   		return ret;
>>   	/*
>> @@ -346,7 +371,10 @@ static int aat1290_led_get_configuration(struct aat1290_led *led,
>>
>>   	aat1290_led_validate_mm_current(led, cfg);
>>
>> -	kfree(led->mm_current_scale);
>> +#if IS_ENABLED(CONFIG_V4L2_FLASH_LED_CLASS)
>> +#else
>> +	devm_kfree(&led->pdev->dev, led->mm_current_scale);
>> +#endif
>>
>>   	return 0;
>>   }
>> @@ -365,6 +393,83 @@ static void aat1290_init_flash_timeout(struct aat1290_led *led,
>>   	setting->val = setting->max;
>>   }
>>
>> +#if IS_ENABLED(CONFIG_V4L2_FLASH_LED_CLASS)
>> +enum led_brightness aat1290_intensity_to_brightness(
>> +					struct v4l2_flash *v4l2_flash,
>> +					s32 intensity)
>> +{
>> +	struct led_classdev_flash *fled_cdev = v4l2_flash->fled_cdev;
>> +	struct aat1290_led *led = fled_cdev_to_led(fled_cdev);
>> +	int i;
>> +
>> +	for (i = AAT1290_MM_CURRENT_SCALE_SIZE - 1; i >= 0; --i)
>> +		if (intensity >= led->mm_current_scale[i])
>> +			return i + 1;
>> +
>> +	return 1;
>> +}
>> +
>> +s32 aat1290_brightness_to_intensity(struct v4l2_flash *v4l2_flash,
>> +					enum led_brightness brightness)
>> +{
>> +	struct led_classdev_flash *fled_cdev = v4l2_flash->fled_cdev;
>> +	struct aat1290_led *led = fled_cdev_to_led(fled_cdev);
>> +
>> +	return led->mm_current_scale[brightness - 1];
>> +}
>> +
>> +static int aat1290_led_external_strobe_set(struct v4l2_flash *v4l2_flash,
>> +						bool enable)
>> +{
>> +	struct aat1290_led *led = fled_cdev_to_led(v4l2_flash->fled_cdev);
>> +	struct led_classdev_flash *fled_cdev = v4l2_flash->fled_cdev;
>> +	struct led_classdev *led_cdev = &fled_cdev->led_cdev;
>> +	struct pinctrl *pinctrl;
>> +
>> +	gpiod_direction_output(led->gpio_fl_en, 0);
>> +	gpiod_direction_output(led->gpio_en_set, 0);
>> +
>> +	led->movie_mode = false;
>> +	led_cdev->brightness = 0;
>> +
>> +	pinctrl = devm_pinctrl_get_select(&led->pdev->dev,
>> +						enable ? "isp" : "host");
>> +	if (IS_ERR(pinctrl)) {
>> +		dev_warn(&led->pdev->dev, "Unable to switch strobe source.\n");
>> +		return PTR_ERR(pinctrl);
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +static void aat1290_init_v4l2_flash_config(struct aat1290_led *led,
>> +					struct aat1290_led_config_data *led_cfg,
>> +					struct v4l2_flash_config *v4l2_sd_cfg)
>> +{
>> +	struct led_classdev *led_cdev = &led->fled_cdev.led_cdev;
>> +	struct led_flash_setting *s;
>> +
>> +	strlcpy(v4l2_sd_cfg->dev_name, led_cdev->name,
>> +		sizeof(v4l2_sd_cfg->dev_name));
>> +
>> +	s = &v4l2_sd_cfg->intensity;
>> +	s->min = led->mm_current_scale[0];
>> +	s->max = led_cfg->max_mm_current;
>> +	s->step = 1;
>> +	s->val = s->max;
>> +
>> +	v4l2_sd_cfg->has_external_strobe = led_cfg->has_external_strobe;
>> +}
>> +
>> +static const struct v4l2_flash_ops v4l2_flash_ops = {
>> +	.external_strobe_set = aat1290_led_external_strobe_set,
>> +	.intensity_to_led_brightness = aat1290_intensity_to_brightness,
>> +	.led_brightness_to_intensity = aat1290_brightness_to_intensity,
>> +};
>> +#else
>> +#define aat1290_init_v4l2_flash_config(led, led_cfg, v4l2_sd_cfg)
>> +#endif
>> +
>>   static const struct led_flash_ops flash_ops = {
>>   	.strobe_set = aat1290_led_flash_strobe_set,
>>   	.timeout_set = aat1290_led_flash_timeout_set,
>> @@ -373,10 +478,14 @@ static const struct led_flash_ops flash_ops = {
>>   static int aat1290_led_probe(struct platform_device *pdev)
>>   {
>>   	struct device *dev = &pdev->dev;
>> +	struct device_node *sub_node = NULL;
>>   	struct aat1290_led *led;
>>   	struct led_classdev *led_cdev;
>>   	struct led_classdev_flash *fled_cdev;
>>   	struct aat1290_led_config_data led_cfg = {};
>> +#if IS_ENABLED(CONFIG_V4L2_FLASH_LED_CLASS)
>> +	struct v4l2_flash_config v4l2_sd_cfg = {};
>> +#endif
>>   	int ret;
>>
>>   	led = devm_kzalloc(dev, sizeof(*led), GFP_KERNEL);
>> @@ -390,7 +499,7 @@ static int aat1290_led_probe(struct platform_device *pdev)
>>   	fled_cdev->ops = &flash_ops;
>>   	led_cdev = &fled_cdev->led_cdev;
>>
>> -	ret = aat1290_led_get_configuration(led, &led_cfg);
>> +	ret = aat1290_led_get_configuration(led, &led_cfg, &sub_node);
>>   	if (ret < 0)
>>   		return ret;
>>
>> @@ -410,8 +519,23 @@ static int aat1290_led_probe(struct platform_device *pdev)
>>   	if (ret < 0)
>>   		goto err_flash_register;
>>
>> +	aat1290_init_v4l2_flash_config(led, &led_cfg, &v4l2_sd_cfg);
>> +
>> +	led_cdev->dev->of_node = sub_node;
>
> What's the reason for this? I can't immediately see how this is being used.

The of_node is used for async sub-device registration. There is a call
made in v4l2_sync_belongs:
	match(sd->dev, asd).

In this case match_of is used which does the comparison:
dev->of_node == asd->match.of.node.

In v4l2_flash_init an assignment is made: sd->dev = led_cdev->dev

> There's also a problem with references, you should grab it here and release
> when it's no longer used.

The reference is grabbed in v4l2_flash_init.

>> +
>> +	/* Create V4L2 Flash subdev. */
>> +	led->v4l2_flash = v4l2_flash_init(fled_cdev,
>> +					  &v4l2_flash_ops,
>> +					  &v4l2_sd_cfg);
>> +	if (IS_ERR(led->v4l2_flash)) {
>> +		ret = PTR_ERR(led->v4l2_flash);
>> +		goto error_v4l2_flash_init;
>> +	}
>> +
>>   	return 0;
>>
>> +error_v4l2_flash_init:
>> +	led_classdev_flash_unregister(fled_cdev);
>>   err_flash_register:
>>   	mutex_destroy(&led->lock);
>>
>> @@ -422,6 +546,7 @@ static int aat1290_led_remove(struct platform_device *pdev)
>>   {
>>   	struct aat1290_led *led = platform_get_drvdata(pdev);
>>
>> +	v4l2_flash_release(led->v4l2_flash);
>>   	led_classdev_flash_unregister(&led->fled_cdev);
>>   	cancel_work_sync(&led->work_brightness_set);
>>
>