Re: [PATCH v2 4/4] leds: Add a multicolor LED driver to group monochromatic LEDs

[Christophe JAILLET <christophe.jaillet@wanadoo.fr>]

Hi,

a few nitpick below.


Le 19/07/2022 à 21:18, Jean-Jacques Hiblot a écrit :
> By allowing to group multiple monochrome LED into multicolor LEDs,
> all involved LEDs can be controlled in-sync. This enables using effects
> using triggers, etc.
> 
> Signed-off-by: Jean-Jacques Hiblot <jjhiblot@traphandler.com>
> ---
>   drivers/leds/rgb/Kconfig                 |   6 +
>   drivers/leds/rgb/Makefile                |   1 +
>   drivers/leds/rgb/leds-group-multicolor.c | 153 +++++++++++++++++++++++
>   3 files changed, 160 insertions(+)
>   create mode 100644 drivers/leds/rgb/leds-group-multicolor.c
> 
> diff --git a/drivers/leds/rgb/Kconfig b/drivers/leds/rgb/Kconfig
> index 204cf470beae..70b157d1fdca 100644
> --- a/drivers/leds/rgb/Kconfig
> +++ b/drivers/leds/rgb/Kconfig
> @@ -2,6 +2,12 @@
>   
>   if LEDS_CLASS_MULTICOLOR
>   
> +config LEDS_GRP_MULTICOLOR
> +	tristate "multi-color LED grouping Support"

Why "Support" and not "support"?

> +	help
> +	  This option enables support for monochrome LEDs that are
> +	  grouped into multicolor LEDs.
> +
>   config LEDS_PWM_MULTICOLOR
>   	tristate "PWM driven multi-color LED Support"
>   	depends on PWM
> diff --git a/drivers/leds/rgb/Makefile b/drivers/leds/rgb/Makefile
> index 0675bc0f6e18..4de087ad79bc 100644
> --- a/drivers/leds/rgb/Makefile
> +++ b/drivers/leds/rgb/Makefile
> @@ -1,4 +1,5 @@
>   # SPDX-License-Identifier: GPL-2.0
>   
> +obj-$(CONFIG_LEDS_GRP_MULTICOLOR)	+= leds-group-multicolor.o
>   obj-$(CONFIG_LEDS_PWM_MULTICOLOR)	+= leds-pwm-multicolor.o
>   obj-$(CONFIG_LEDS_QCOM_LPG)		+= leds-qcom-lpg.o
> diff --git a/drivers/leds/rgb/leds-group-multicolor.c b/drivers/leds/rgb/leds-group-multicolor.c
> new file mode 100644
> index 000000000000..be71b85edfb5
> --- /dev/null
> +++ b/drivers/leds/rgb/leds-group-multicolor.c
> @@ -0,0 +1,153 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * multi-color LED built with monochromatic LED devices
> + *
> + * Copyright 2022 Jean-Jacques Hiblot <jjhiblot@traphandler.com>
> + */
> +
> +#include <linux/err.h>
> +#include <linux/led-class-multicolor.h>
> +#include <linux/leds.h>
> +#include <linux/math.h>
> +#include <linux/mod_devicetable.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/platform_device.h>
> +#include <linux/property.h>
> +
> +struct led_mcg_priv {
> +	struct led_classdev_mc mc_cdev;
> +	struct led_classdev **monochromatics;
> +};
> +
> +static int led_mcg_set(struct led_classdev *cdev,
> +			  enum led_brightness brightness)
> +{
> +	struct led_classdev_mc *mc_cdev = lcdev_to_mccdev(cdev);
> +	struct led_mcg_priv *priv =
> +		container_of(mc_cdev, struct led_mcg_priv, mc_cdev);
> +	int i;
> +
> +	led_mc_calc_color_components(mc_cdev, brightness);
> +
> +	for (i = 0; i < mc_cdev->num_colors; i++) {
> +		struct led_classdev *mono = priv->monochromatics[i];
> +		int actual_led_brightness;
> +
> +		/*
> +		 * Scale the intensity according the max brightness of the
> +		 * monochromatic LED
> +		 */
> +		actual_led_brightness = DIV_ROUND_CLOSEST(
> +			mono->max_brightness * mc_cdev->subled_info[i].brightness,
> +			mc_cdev->led_cdev.max_brightness);
> +
> +		led_set_brightness(mono, actual_led_brightness);
> +	}
> +	return 0;
> +}
> +
> +static int led_mcg_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct led_init_data init_data = {};
> +	struct led_classdev *cdev;
> +	struct mc_subled *subled;
> +	struct led_mcg_priv *priv;
> +	int i, count, ret;
> +	unsigned int max_brightness;
> +
> +	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
> +	if (!priv)
> +		return  -ENOMEM;

Extra space between "return" and "-ENOMEM".

> +
> +	dev_set_drvdata(&pdev->dev, priv);

Is it needed?
(apparently, there is no dev_get_drvdata())

> +
> +

One empty line is enough.

> +	count = 0;
> +	max_brightness = 0;

Could be initialized when the variable are declared, as already done 
with "init_data". I guess it is a matter of taste.

> +	for (;;) {
> +		struct led_classdev *led_cdev;
> +
> +		led_cdev = devm_of_led_get(dev, count);
> +		if (IS_ERR(led_cdev)) {
> +			/* Reached the end of the list ? */
> +			if (PTR_ERR(led_cdev) == -ENOENT)
> +				break;
> +			return dev_err_probe(dev, PTR_ERR(led_cdev),
> +					     "Unable to get led #%d", i);

"i" is not used yet. "count"?

> +		}
> +		count++;
> +
> +		/* Make the sysfs of the monochromatic LED read-only */
> +		led_cdev->flags |= LED_SYSFS_DISABLE;
> +
> +		priv->monochromatics = devm_krealloc(dev, priv->monochromatics,
> +					count * sizeof(*priv->monochromatics),
> +					GFP_KERNEL);
> +		if (!priv->monochromatics)
> +			return -ENOMEM;
> +
> +		priv->monochromatics[count - 1] = led_cdev;
> +
> +		max_brightness = max(max_brightness, led_cdev->max_brightness);
> +	}
> +
> +	subled = devm_kzalloc(dev, count * sizeof(*subled), GFP_KERNEL);
> +	if (!subled)
> +		return -ENOMEM;
> +	priv->mc_cdev.subled_info = subled;
> +
> +	for (i = 0; i < count; i++) {
> +		struct led_classdev *led_cdev = priv->monochromatics[i];
> +
> +		subled[i].color_index = led_cdev->color;
> +		/* by default all LEDs have full intensity */
> +		subled[i].intensity = max_brightness;
> +

Uneeded empty line.

> +	}
> +
> +	/* init the multicolor's LED class device */
> +	cdev = &priv->mc_cdev.led_cdev;
> +	cdev->flags = LED_CORE_SUSPENDRESUME;
> +	cdev->brightness_set_blocking = led_mcg_set;
> +	cdev->max_brightness = max_brightness;
> +	cdev->color = LED_COLOR_ID_MULTI;
> +	priv->mc_cdev.num_colors = count;
> +
> +	init_data.fwnode = of_fwnode_handle(dev_of_node(dev));
> +	ret = devm_led_classdev_multicolor_register_ext(dev, &priv->mc_cdev,
> +							&init_data);
> +	if (ret)
> +		return dev_err_probe(dev, ret,
> +			"failed to register multicolor led for %s: %d\n",
> +			cdev->name, ret);

No need to add 'ret' in the message, dev_err_probe() already display it.

> +
> +	ret = led_mcg_set(cdev, cdev->brightness);
> +	if (ret)
> +		return dev_err_probe(dev, ret,
> +				     "failed to set led value for %s: %d",
> +				     cdev->name, ret);

same here.

> +
> +	return 0;
> +}
> +
> +static const struct of_device_id of_led_mcg_match[] = {
> +	{ .compatible = "leds-group-multicolor" },
> +	{}
> +};
> +MODULE_DEVICE_TABLE(of, of_led_mcg_match);
> +
> +static struct platform_driver led_mcg_driver = {
> +	.probe		= led_mcg_probe,
> +	.driver		= {
> +		.name	= "leds_group_multicolor",
> +		.of_match_table = of_led_mcg_match,
> +	}
> +};
> +module_platform_driver(led_mcg_driver);
> +
> +MODULE_AUTHOR("Jean-Jacques Hiblot <jjhiblot@traphandler.com>");
> +MODULE_DESCRIPTION("multi-color LED group driver");
> +MODULE_LICENSE("GPL");
> +MODULE_ALIAS("platform:leds-group-multicolor");