Message-ID: <f43bf4c5-948d-b87f-9b95-98fcfeaae2fa@gmail.com>
Date:   Sat, 28 Mar 2020 15:03:30 +0100
From:   Jacek Anaszewski <jacek.anaszewski@...il.com>
To:     Dan Murphy <dmurphy@...com>, pavel@....cz
Cc:     linux-leds@...r.kernel.org, linux-kernel@...r.kernel.org,
        Greg KH <gregkh@...uxfoundation.org>
Subject: Re: [PATCH v18 4/4] leds: multicolor: Introduce a multicolor class
 definition

Hi Dan,

Thanks for the update. The picture would be more complete if
the patch set contained a client though.

Anyway, please find my review remarks below.

On 3/24/20 7:14 PM, Dan Murphy wrote:
> Introduce a multicolor class that groups colored LEDs
> within a LED node.
> 
> The multi color class groups monochrome LEDs and allows controlling two
> aspects of the final combined color: hue and lightness. The former is
> controlled via color_intensity files and the latter is controlled

s/files/file/

> via brightness file.
> 
> CC: Greg KH <gregkh@...uxfoundation.org>
> Signed-off-by: Dan Murphy <dmurphy@...com>
> ---
> A design alternative to having files that having multiple values written to a
> single file is here:
> 
> https://lore.kernel.org/patchwork/patch/1186194/
> 
>  .../ABI/testing/sysfs-class-led-multicolor    |  51 ++++
>  Documentation/leds/index.rst                  |   1 +
>  Documentation/leds/leds-class-multicolor.rst  | 110 +++++++++
>  drivers/leds/Kconfig                          |  10 +
>  drivers/leds/Makefile                         |   1 +
>  drivers/leds/led-class-multicolor.c           | 224 ++++++++++++++++++
>  include/linux/led-class-multicolor.h          | 124 ++++++++++
>  7 files changed, 521 insertions(+)
>  create mode 100644 Documentation/ABI/testing/sysfs-class-led-multicolor
>  create mode 100644 Documentation/leds/leds-class-multicolor.rst
>  create mode 100644 drivers/leds/led-class-multicolor.c
>  create mode 100644 include/linux/led-class-multicolor.h
> 
> diff --git a/Documentation/ABI/testing/sysfs-class-led-multicolor b/Documentation/ABI/testing/sysfs-class-led-multicolor
> new file mode 100644
> index 000000000000..a93772212c21
> --- /dev/null
> +++ b/Documentation/ABI/testing/sysfs-class-led-multicolor
> @@ -0,0 +1,51 @@
> +What:		/sys/class/leds/<led>/brightness
> +Date:		March 2020
> +KernelVersion:	5.8
> +Contact:	Dan Murphy <dmurphy@...com>
> +Description:	read/write
> +		Writing to this file will update all LEDs within the group to a
> +		calculated percentage of what each color LED intensity is set
> +		to. The percentage is calculated for each grouped LED via the
> +		equation below:
> +
> +		led_brightness = brightness * <color>_intensity/<color>_max_intensity

We now have a single color_intensity file, so this needs to be rephrased.

> +
> +		For additional details please refer to
> +		Documentation/leds/leds-class-multicolor.rst.
> +
> +		The value of the color is from 0 to
> +		/sys/class/leds/<led>/max_brightness.
> +
> +What:		/sys/class/leds/<led>/color_index
> +Date:		March 2020
> +KernelVersion:	5.8
> +Contact:	Dan Murphy <dmurphy@...com>
> +Description:	read
> +		The color_index array, when read, will output the LED colors
> +		by name as they are indexed in the color_intensity array.
> +
> +What:		/sys/class/leds/<led>/num_color_leds

I would go for just num_colors.

> +Date:		March 2020
> +KernelVersion:	5.8
> +Contact:	Dan Murphy <dmurphy@...com>
> +Description:	read
> +		The num_color_leds indicates the number of LEDs defined in the
> +		color_intensity, color_max_intensity and color_index arrays.
> +
> +What:		/sys/class/leds/<led>/color_max_intensity
> +Date:		March 2020
> +KernelVersion:	5.8
> +Contact:	Dan Murphy <dmurphy@...com>
> +Description:	read
> +		Maximum intensity level for the LED color within the array.
> +		The max intensities for each color must be entered based on the
> +		color_index array.

I wonder if we should mention here that each LED within a cluster should
have the same maximum intensity for linear color lightness calculation
via brightness file.

> +
> +What:		/sys/class/leds/<led>/color_intensity
> +Date:		March 2020
> +KernelVersion:	5.8
> +Contact:	Dan Murphy <dmurphy@...com>
> +Description:	read/write
> +		Intensity level for the LED color within the array.
> +		The intensities for each color must be entered based on the
> +		color_index array.
> diff --git a/Documentation/leds/index.rst b/Documentation/leds/index.rst
> index 060f4e485897..bc70c6aa7138 100644
> --- a/Documentation/leds/index.rst
> +++ b/Documentation/leds/index.rst
> @@ -9,6 +9,7 @@ LEDs
>  
>     leds-class
>     leds-class-flash
> +   leds-class-multicolor
>     ledtrig-oneshot
>     ledtrig-transient
>     ledtrig-usbport
> diff --git a/Documentation/leds/leds-class-multicolor.rst b/Documentation/leds/leds-class-multicolor.rst
> new file mode 100644
> index 000000000000..902a281a44d4
> --- /dev/null
> +++ b/Documentation/leds/leds-class-multicolor.rst
> @@ -0,0 +1,110 @@
> +====================================
> +Multi Color LED handling under Linux
> +====================================
> +
> +Description
> +===========
> +The multi color class groups monochrome LEDs and allows controlling two
> +aspects of the final combined color: hue and lightness. The former is
> +controlled via the color_intensity array file and the latter is controlled
> +via brightness file.
> +
> +For more details on hue and lightness notions please refer to
> +https://en.wikipedia.org/wiki/CIECAM02.
> +
> +Note that intensity file only caches the written values and the actual

s/intensity/color_intensity/

> +change of hardware state occurs upon writing brightness file. This
> +allows for changing many factors of the perceived color in a virtually
> +unnoticeable way for the human observer.

It will have to be changed after we agree upon exact semantics and
interface of color_intensity, as I raised an issue below.

> +
> +Multicolor Class Control
> +========================
> +The multicolor class presents files that groups the colors as indexes in an
> +array.  These files are children under the LED parent node created by the
> +led_class framework.  The led_class framework is documented in led-class.rst
> +within this documentation directory.
> +
> +Each colored LED will be indexed under the color_* files. The order of the
> +colors are arbitrary the color_index file can be read to determine the color
> +to index value.

This paragraph seems to be a leftover from some older version of the
patch set.

> +
> +The color_index file is an array that contains the string list of the colors as
> +they are defined in each color_* array file.
> +
> +The color_intensity is an array that can be read or written to for the
> +individual color intensities.  All elements within this array must be written in
> +order for the color LED intensities to be updated.
> +
> +The color_max_intensity is an array that can be read to indicate each color LED
> +maximum intensity value.
> +
> +The num_color_leds file returns the total number of color LEDs that are
> +presented in each color_* array.
> +
> +Directory Layout Example
> +========================
> +root:/sys/class/leds/multicolor:grouped_leds# ls -lR
> +-rw-r--r--    1 root     root          4096 Oct 19 16:16 brightness
> +-r--r--r--    1 root     root          4096 Oct 19 16:16 color_index
> +-rw-r--r--    1 root     root          4096 Oct 19 16:16 color_intensity
> +-r--r--r--    1 root     root          4096 Oct 19 16:16 color_max_intensity
> +-r--r--r--    1 root     root          4096 Oct 19 16:16 num_color_leds
> +
> +Multicolor Class Brightness Control
> +===================================
> +The multiclor class framework will calculate each monochrome LEDs intensity.
> +
> +The brightness level for each LED is calculated based on the color LED
> +intensity setting divided by the color LED max intensity setting multiplied by
> +the requested brightness.
> +
> +led_brightness = brightness * color_intensity/color_max_intensity

Maybe some pseudo code would allow for better understanding here:

for color in color_intensity
    led[color].brightness = brightness *
	led[color].intensity / led[color].max_intensity

> +
> +It is important to note that for each LED within the cluster the
> +color_max_intensity value should be the same. This will help maintain a
> +consistent hue across brightness levels.
> +
> +Example:
> +A user first writes the color LEDs intensity file with the brightness levels

s/color LEDs intensity/color_intensity/

> +that for each LED that is necessary to achieve a blueish violet output from a
> +RGB LED group.
> +
> +cat /sys/class/leds/multicolor:grouped_leds/color_index

We don't have "grouped_leds" LED function so let's better use
something available, like e.g "status".

> +green blue red
> +
> +echo 43 226 138 > /sys/class/leds/multicolor:grouped_leds/color_intensity
> +
> +red -
> +	intensity = 138
> +	max_intensity = 255
> +green -
> +	intensity = 43
> +	max_intensity = 255
> +blue -
> +	intensity = 226
> +	max_intensity = 255
> +
> +The user can control the brightness of that RGB group by writing the parent
> +'brightness' control.  Assuming a parent max_brightness of 255 the user may want
> +to dim the LED color group to half.  The user would write a value of 128 to the
> +parent brightness file then the values written to each LED will be adjusted
> +base on this value
> +
> +cat /sys/class/leds/multicolor:grouped_leds/max_brightness
> +255
> +echo 128 > /sys/class/leds/multicolor:grouped_leds/brightness
> +
> +adjusted_red_value = 128 * 138/255 = 69
> +adjusted_green_value = 128 * 43/255 = 21
> +adjusted_blue_value = 128 * 226/255 = 113
> +
> +Reading the parent brightness file will return the current brightness value of
> +the color LED group.
> +
> +cat /sys/class/leds/multicolor:grouped_leds/max_brightness
> +255
> +
> +echo 128 > /sys/class/leds/multicolor:grouped_leds/brightness

It was already written once above, no need to repeat.

> +
> +cat /sys/class/leds/multicolor:grouped_leds/brightness
> +128
> diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
> index d82f1dea3711..37dcdb06a29b 100644
> --- a/drivers/leds/Kconfig
> +++ b/drivers/leds/Kconfig
> @@ -30,6 +30,16 @@ config LEDS_CLASS_FLASH
>  	  for the flash related features of a LED device. It can be built
>  	  as a module.
>  
> +config LEDS_CLASS_MULTI_COLOR
> +	tristate "LED Mulit Color LED Class Support"
> +	depends on LEDS_CLASS
> +	help
> +	  This option enables the multicolor LED sysfs class in /sys/class/leds.
> +	  It wraps LED class and adds multicolor LED specific sysfs attributes
> +	  and kernel internal API to it. You'll need this to provide support
> +	  for multicolor LEDs that are grouped together. This class is not
> +	  intended for single color LEDs. It can be built as a module.
> +
>  config LEDS_BRIGHTNESS_HW_CHANGED
>  	bool "LED Class brightness_hw_changed attribute support"
>  	depends on LEDS_CLASS
> diff --git a/drivers/leds/Makefile b/drivers/leds/Makefile
> index d7e1107753fb..310b5518783a 100644
> --- a/drivers/leds/Makefile
> +++ b/drivers/leds/Makefile
> @@ -4,6 +4,7 @@
>  obj-$(CONFIG_NEW_LEDS)			+= led-core.o
>  obj-$(CONFIG_LEDS_CLASS)		+= led-class.o
>  obj-$(CONFIG_LEDS_CLASS_FLASH)		+= led-class-flash.o
> +obj-$(CONFIG_LEDS_CLASS_MULTI_COLOR)	+= led-class-multicolor.o
>  obj-$(CONFIG_LEDS_TRIGGERS)		+= led-triggers.o
>  
>  # LED Platform Drivers
> diff --git a/drivers/leds/led-class-multicolor.c b/drivers/leds/led-class-multicolor.c
> new file mode 100644
> index 000000000000..0dbafede6e58
> --- /dev/null
> +++ b/drivers/leds/led-class-multicolor.c
> @@ -0,0 +1,224 @@
> +// SPDX-License-Identifier: GPL-2.0
> +// LED Multi Color class interface
> +// Copyright (C) 2019 Texas Instruments Incorporated - http://www.ti.com/

I think that you deserve mentioning yourself as an author too.

> +
> +#include <linux/device.h>
> +#include <linux/init.h>
> +#include <linux/led-class-multicolor.h>
> +#include <linux/module.h>
> +#include <linux/slab.h>
> +#include <linux/uaccess.h>
> +
> +#include "leds.h"
> +
> +int led_mc_calc_color_components(struct led_classdev_mc *mcled_cdev,
> +				 enum led_brightness brightness)
> +{
> +	int i;
> +
> +	for (i = 0; i < mcled_cdev->num_colors; i++)
> +		mcled_cdev->color_brightness[i] = brightness *
> +					  mcled_cdev->color_led_intensity[i] /
> +					  mcled_cdev->color_led_max_intensity[i];
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(led_mc_calc_color_components);
> +
> +static ssize_t color_intensity_store(struct device *dev,
> +				struct device_attribute *intensity_attr,
> +				const char *buf, size_t size)
> +{
> +	struct led_classdev *led_cdev = dev_get_drvdata(dev);
> +	struct led_classdev_mc *priv = lcdev_to_mccdev(led_cdev);
> +	int nrchars, offset = 0;
> +	int intensity_value[LED_COLOR_ID_MAX];
> +	int i;
> +	ssize_t ret;
> +
> +	mutex_lock(&led_cdev->led_access);
> +
> +	for (i = 0; i < priv->num_colors; i++) {
> +		ret = sscanf(buf + offset, "%i%n",
> +			     &intensity_value[i], &nrchars);
> +		if (ret != 1) {
> +			dev_err(led_cdev->dev,
> +				"Incorrect number of LEDs expected %i values intensity was not applied\n",
> +				priv->num_colors);
> +			goto err_out;
> +		}
> +		offset += nrchars;
> +	}

I've just realized that moving to single color_intensity file
doesn't allow setting all colors together with new brightness
atomically. In effect, we will need to pass brightness to this file too,
if we want to avoid "interesting" latching via brightenss file.

Then we would need to call led_set_brightness() from here as well.

> +
> +	memcpy(&priv->color_led_intensity, intensity_value,
> +	       sizeof(intensity_value));
> +err_out:
> +	ret = size;
> +	mutex_unlock(&led_cdev->led_access);
> +	return ret;
> +}
> +
> +static ssize_t color_intensity_show(struct device *dev,
> +			      struct device_attribute *intensity_attr,
> +			      char *buf)
> +{
> +	struct led_classdev *led_cdev = dev_get_drvdata(dev);
> +	struct led_classdev_mc *priv = lcdev_to_mccdev(led_cdev);
> +	int len = 0;
> +	int i;
> +
> +	for (i = 0; i < priv->num_colors; i++)
> +		len += sprintf(buf + len, "%d ", priv->color_led_intensity[i]);
> +
> +	len += sprintf(buf + len, "%s", "\n");
> +
> +	return len;
> +}
> +static DEVICE_ATTR_RW(color_intensity);
> +
> +static ssize_t color_index_show(struct device *dev,
> +			      struct device_attribute *color_index_attr,
> +			      char *buf)
> +{
> +	struct led_classdev *led_cdev = dev_get_drvdata(dev);
> +	struct led_classdev_mc *priv = lcdev_to_mccdev(led_cdev);
> +	int len = 0;
> +	int i;
> +
> +	for (i = 0; i < priv->num_colors; i++)
> +		len += sprintf(buf + len, "%s ", priv->color_index[i]);
> +
> +	len += sprintf(buf + len, "%s", "\n");
> +
> +	return len;
> +}
> +static DEVICE_ATTR_RO(color_index);
> +
> +static ssize_t color_max_intensity_show(struct device *dev,
> +				   struct device_attribute *max_intensity_attr,
> +				   char *buf)
> +{
> +	struct led_classdev *led_cdev = dev_get_drvdata(dev);
> +	struct led_classdev_mc *priv = lcdev_to_mccdev(led_cdev);
> +	int len = 0;
> +	int i;
> +
> +	for (i = 0; i < priv->num_colors; i++)
> +		len += sprintf(buf + len, "%d ",
> +			       priv->color_led_max_intensity[i]);
> +
> +	len += sprintf(buf + len, "%s", "\n");
> +
> +	return len;
> +}
> +static DEVICE_ATTR_RO(color_max_intensity);
> +
> +static ssize_t num_color_leds_show(struct device *dev,
> +				   struct device_attribute *max_intensity_attr,
> +				   char *buf)
> +{
> +	struct led_classdev *led_cdev = dev_get_drvdata(dev);
> +	struct led_classdev_mc *priv = lcdev_to_mccdev(led_cdev);
> +
> +	return sprintf(buf, "%d\n", priv->num_colors);
> +}
> +static DEVICE_ATTR_RO(num_color_leds);
> +
> +static struct attribute *led_multicolor_attrs[] = {
> +	&dev_attr_color_intensity.attr,
> +	&dev_attr_color_index.attr,
> +	&dev_attr_color_max_intensity.attr,
> +	&dev_attr_num_color_leds.attr,
> +	NULL,
> +};
> +ATTRIBUTE_GROUPS(led_multicolor);
> +
> +int led_classdev_multicolor_register_ext(struct device *parent,
> +				     struct led_classdev_mc *mcled_cdev,
> +				     struct led_init_data *init_data)
> +{
> +	struct led_classdev *led_cdev;
> +	int i;
> +
> +	if (!mcled_cdev)
> +		return -EINVAL;
> +
> +	if (!mcled_cdev->num_colors)
> +		return -EINVAL;
> +
> +	led_cdev = &mcled_cdev->led_cdev;
> +
> +	mcled_cdev->led_cdev.groups = led_multicolor_groups;
> +
> +	for (i = 0; i <= mcled_cdev->num_colors; i++)
> +		if (!mcled_cdev->color_led_max_intensity[i])
> +			mcled_cdev->color_led_max_intensity[i] = LED_FULL;
> +
> +	return led_classdev_register_ext(parent, &mcled_cdev->led_cdev,
> +					 init_data);
> +}
> +EXPORT_SYMBOL_GPL(led_classdev_multicolor_register_ext);
> +
> +void led_classdev_multicolor_unregister(struct led_classdev_mc *mcled_cdev)
> +{
> +	if (!mcled_cdev)
> +		return;
> +
> +	led_classdev_unregister(&mcled_cdev->led_cdev);
> +}
> +EXPORT_SYMBOL_GPL(led_classdev_multicolor_unregister);
> +
> +static void devm_led_classdev_multicolor_release(struct device *dev, void *res)
> +{
> +	led_classdev_multicolor_unregister(*(struct led_classdev_mc **)res);
> +}
> +
> +int devm_led_classdev_multicolor_register_ext(struct device *parent,
> +					     struct led_classdev_mc *mcled_cdev,
> +					      struct led_init_data *init_data)
> +{
> +	struct led_classdev_mc **dr;
> +	int ret;
> +
> +	dr = devres_alloc(devm_led_classdev_multicolor_release,
> +			  sizeof(*dr), GFP_KERNEL);
> +	if (!dr)
> +		return -ENOMEM;
> +
> +	ret = led_classdev_multicolor_register_ext(parent, mcled_cdev,
> +						   init_data);
> +	if (ret) {
> +		devres_free(dr);
> +		return ret;
> +	}
> +
> +	*dr = mcled_cdev;
> +	devres_add(parent, dr);
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(devm_led_classdev_multicolor_register_ext);
> +
> +static int devm_led_classdev_multicolor_match(struct device *dev,
> +					      void *res, void *data)
> +{
> +	struct led_classdev_mc **p = res;
> +
> +	if (WARN_ON(!p || !*p))
> +		return 0;
> +
> +	return *p == data;
> +}
> +
> +void devm_led_classdev_multicolor_unregister(struct device *dev,
> +					     struct led_classdev_mc *mcled_cdev)
> +{
> +	WARN_ON(devres_release(dev,
> +			       devm_led_classdev_multicolor_release,
> +			       devm_led_classdev_multicolor_match, mcled_cdev));
> +}
> +EXPORT_SYMBOL_GPL(devm_led_classdev_multicolor_unregister);
> +
> +MODULE_AUTHOR("Dan Murphy <dmurphy@...com>");
> +MODULE_DESCRIPTION("Multi Color LED class interface");
> +MODULE_LICENSE("GPL v2");
> diff --git a/include/linux/led-class-multicolor.h b/include/linux/led-class-multicolor.h
> new file mode 100644
> index 000000000000..bfbde2e98340
> --- /dev/null
> +++ b/include/linux/led-class-multicolor.h
> @@ -0,0 +1,124 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/* LED Multicolor class interface
> + * Copyright (C) 2019 Texas Instruments Incorporated - http://www.ti.com/
> + */
> +
> +#ifndef __LINUX_MULTICOLOR_LEDS_H_INCLUDED
> +#define __LINUX_MULTICOLOR_LEDS_H_INCLUDED
> +
> +#include <linux/leds.h>
> +#include <dt-bindings/leds/common.h>
> +
> +struct led_classdev_mc {
> +	/* led class device */
> +	struct led_classdev led_cdev;
> +
> +	struct device_attribute color_max_intensity_attr;
> +	struct device_attribute color_intensity_attr;
> +	struct device_attribute color_index_attr;

These are no longer needed as you define attrs statically.

> +
> +	int color_brightness[LED_COLOR_ID_MAX];
> +
> +	int color_led_intensity[LED_COLOR_ID_MAX];
> +	int color_led_max_intensity[LED_COLOR_ID_MAX];
> +	const char *color_index[LED_COLOR_ID_MAX];

I think that we should get back to the available_colors bitmask
and allow the framework to allocate arrays by itself.
And yes, all the above should be pointers.

Driver would only need to set led_mcdev->available_colors bits.

> +
> +	int num_colors;
> +};
> +
> +static inline struct led_classdev_mc *lcdev_to_mccdev(
> +						struct led_classdev *led_cdev)
> +{
> +	return container_of(led_cdev, struct led_classdev_mc, led_cdev);
> +}
> +
> +#if IS_ENABLED(CONFIG_LEDS_CLASS_MULTI_COLOR)
> +/**
> + * led_classdev_multicolor_register_ext - register a new object of led_classdev
> + *				      class with support for multicolor LEDs
> + * @parent: the multicolor LED to register
> + * @mcled_cdev: the led_classdev_mc structure for this device
> + * @init_data: the LED class Multi color device initialization data
> + *
> + * Returns: 0 on success or negative error value on failure
> + */
> +int led_classdev_multicolor_register_ext(struct device *parent,
> +					    struct led_classdev_mc *mcled_cdev,
> +					    struct led_init_data *init_data);
> +
> +static inline int led_classdev_multicolor_register(struct device *parent,
> +					    struct led_classdev_mc *mcled_cdev)
> +{
> +	return led_classdev_multicolor_register_ext(parent, mcled_cdev, NULL);
> +}
> +
> +/**
> + * led_classdev_multicolor_unregister - unregisters an object of led_classdev
> + *					class with support for multicolor LEDs
> + * @mcled_cdev: the multicolor LED to unregister
> + *
> + * Unregister a previously registered via led_classdev_multicolor_register
> + * object
> + */
> +void led_classdev_multicolor_unregister(struct led_classdev_mc *mcled_cdev);
> +
> +/* Calculate brightness for the monochrome LED cluster */
> +int led_mc_calc_color_components(struct led_classdev_mc *mcled_cdev,
> +				 enum led_brightness brightness);
> +
> +int devm_led_classdev_multicolor_register_ext(struct device *parent,
> +					  struct led_classdev_mc *mcled_cdev,
> +					  struct led_init_data *init_data);
> +
> +static inline int devm_led_classdev_multicolor_register(struct device *parent,
> +				     struct led_classdev_mc *mcled_cdev)
> +{
> +	return devm_led_classdev_multicolor_register_ext(parent, mcled_cdev,
> +							 NULL);
> +}
> +
> +void devm_led_classdev_multicolor_unregister(struct device *parent,
> +					    struct led_classdev_mc *mcled_cdev);
> +#else
> +
> +static inline  int led_classdev_multicolor_register_ext(struct device *parent,
> +					    struct led_classdev_mc *mcled_cdev,
> +					    struct led_init_data *init_data)
> +{
> +	return -EINVAL;
> +}
> +
> +static inline int led_classdev_multicolor_register(struct device *parent,
> +					    struct led_classdev_mc *mcled_cdev)
> +{
> +	return led_classdev_multicolor_register_ext(parent, mcled_cdev, NULL);
> +}
> +
> +static inline void led_classdev_multicolor_unregister(struct led_classdev_mc *mcled_cdev) {};
> +static inline int led_mc_calc_color_components(struct led_classdev_mc *mcled_cdev,
> +					       enum led_brightness brightness,
> +			     struct led_mc_color_conversion color_components[])
> +{
> +	return -EINVAL;
> +}
> +
> +static inline int devm_led_classdev_multicolor_register_ext(struct device *parent,
> +					  struct led_classdev_mc *mcled_cdev,
> +					  struct led_init_data *init_data)
> +{
> +	return -EINVAL;
> +}
> +
> +static inline int devm_led_classdev_multicolor_register(struct device *parent,
> +					     struct led_classdev_mc *mcled_cdev)
> +{
> +	return devm_led_classdev_multicolor_register_ext(parent, mcled_cdev,
> +							 NULL);
> +}
> +
> +static inline void devm_led_classdev_multicolor_unregister(struct device *parent,
> +					    struct led_classdev_mc *mcled_cdev)
> +{};
> +
> +#endif  /* IS_ENABLED(CONFIG_LEDS_CLASS_MULTI_COLOR) */
> +#endif	/* __LINUX_MULTICOLOR_LEDS_H_INCLUDED */
> 

-- 
Best regards,
Jacek Anaszewski

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