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Message-ID: <20230315155241.GA9667@google.com>
Date: Wed, 15 Mar 2023 15:52:41 +0000
From: Lee Jones <lee@...nel.org>
To: Jean-Jacques Hiblot <jjhiblot@...phandler.com>
Cc: lee.jones@...aro.org, pavel@....cz, robh+dt@...nel.org,
sven.schwermer@...ruptive-technologies.com,
krzysztof.kozlowski+dt@...aro.org, johan+linaro@...nel.org,
marijn.suijten@...ainline.org, andy.shevchenko@...il.com,
jacek.anaszewski@...il.com, linux-leds@...r.kernel.org,
devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v7 6/6] leds: Add a multicolor LED driver to group
monochromatic LEDs
On Mon, 02 Jan 2023, Jean-Jacques Hiblot wrote:
> By allowing to group multiple monochrome LED into multicolor LEDs,
Nit: s/LED/LEDs/
> all involved LEDs can be controlled in-sync. This enables using effects
> using triggers, etc.
Too many "using"s. Please reword.
> Signed-off-by: Jean-Jacques Hiblot <jjhiblot@...phandler.com>
> ---
> drivers/leds/rgb/Kconfig | 10 ++
> drivers/leds/rgb/Makefile | 1 +
> drivers/leds/rgb/leds-group-multicolor.c | 166 +++++++++++++++++++++++
> 3 files changed, 177 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..1a87f53faa8a 100644
> --- a/drivers/leds/rgb/Kconfig
> +++ b/drivers/leds/rgb/Kconfig
> @@ -2,6 +2,16 @@
>
> if LEDS_CLASS_MULTICOLOR
>
> +config LEDS_GRP_MULTICOLOR
Shortening "GROUP" saves nothing here and hurts readability.
Please expand it.
> + tristate "Multi-color LED grouping support"
Is it "multi-color group" or "group multi-color"?
Please be consistent throughout the whole driver.
I suggest "LEDs group multi-color" throughout.
> + depends on COMPILE_TEST || OF
These usually appear the other way around.
> + help
> + This option enables support for monochrome LEDs that are
> + grouped into multicolor LEDs.
Useful because ...
> + To compile this driver as a module, choose M here: the module
> + will be called leds-grp-multicolor.
> +
> 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..1c99bedf8979
> --- /dev/null
> +++ b/drivers/leds/rgb/leds-group-multicolor.c
> @@ -0,0 +1,166 @@
> +// SPDX-License-Identifier: GPL-2.0-only
Why "only"?
> +/*
> + * multi-color LED built with monochromatic LED devices
Please expand a little.
> + * Copyright 2022 Jean-Jacques Hiblot <jjhiblot@...phandler.com>
Please update.
> + */
> +
> +#include <linux/err.h>
> +#include <linux/leds.h>
> +#include <linux/led-class-multicolor.h>
> +#include <linux/math.h>
> +#include <linux/module.h>
> +#include <linux/mod_devicetable.h>
> +#include <linux/platform_device.h>
> +#include <linux/property.h>
> +
> +struct led_mcg_priv {
Open out "mcg" everywhere.
Readability / maintainability is a high priority.
> + struct led_classdev_mc mc_cdev;
> + struct led_classdev **monochromatics;
If this is an array, better to be explicit.
*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);
> + const unsigned int mc_max_brightness = mc_cdev->led_cdev.max_brightness;
> + int i;
> +
> + for (i = 0; i < mc_cdev->num_colors; i++) {
> + struct led_classdev *mono = priv->monochromatics[i];
> + const unsigned int mono_max = mono->max_brightness;
You lose the meaning of the variable here.
"mono_max" max what?
> + unsigned int rel_intensity = mc_cdev->subled_info[i].intensity;
> + int b;
'b' is a terrible name for a variable.
> + /*
> + * Scale the brightness according to relative intensity of the
> + * color AND the max brightness of the monochromatic LED.
> + */
> + b = DIV_ROUND_CLOSEST(brightness * rel_intensity * mono_max,
> + mc_max_brightness * mc_max_brightness);
> +
> + led_set_brightness(mono, b);
> + }
> +
> + return 0;
> +}
> +
> +static void restore_sysfs_access(void *data)
> +{
> + struct led_classdev *led_cdev = data;
> +
> + mutex_lock(&led_cdev->led_access);
> + led_sysfs_enable(led_cdev);
> + mutex_unlock(&led_cdev->led_access);
> +}
> +
> +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;
> + unsigned int max_brightness;
> + int i, count, ret;
> +
> + priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
> + if (!priv)
> + return -ENOMEM;
> +
> + count = 0;
> + max_brightness = 0;
Initialise these during definition.
> + for (;;) {
> + struct led_classdev *led_cdev;
> +
> + led_cdev = devm_of_led_get_optional(dev, count);
> + if (IS_ERR(led_cdev))
Doesn't devm_of_led_get_optional() return NULL on failure?
> + return dev_err_probe(dev, PTR_ERR(led_cdev),
> + "Unable to get led #%d", count);
> + /* Reached the end of the list ?*/
Besides the incorrect formatting, that '?' isn't filling me with
confidence.
> + if (!led_cdev)
> + break;
> +
> + priv->monochromatics = devm_krealloc_array(dev, priv->monochromatics,
> + count + 1, sizeof(*priv->monochromatics),
> + GFP_KERNEL);
> + if (!priv->monochromatics)
> + return -ENOMEM;
> +
> + priv->monochromatics[count] = led_cdev;
> +
> + max_brightness = max(max_brightness, led_cdev->max_brightness);
> + count++;
> + }
> +
> + subled = devm_kcalloc(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;
'\n'
> + /* configure the LED intensity to its maximum */
Use correct grammar in comments please.
Start with an uppercase char.
> + subled[i].intensity = max_brightness;
> + }
> +
> + /* init the multicolor's LED class device */
As above and please be fully forthcoming in comments: "Initialise".
> + 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 = dev_fwnode(dev);
> + ret = devm_led_classdev_multicolor_register_ext(dev, &priv->mc_cdev,
> + &init_data);
Use the full 100-char limit everywhere please.
> + if (ret)
> + return dev_err_probe(dev, ret,
> + "failed to register multicolor led for %s.\n",
"LED"
> + cdev->name);
> +
> + ret = led_mcg_set(cdev, cdev->brightness);
> + if (ret)
> + return dev_err_probe(dev, ret,
> + "failed to set led value for %s.",
> + cdev->name);
> +
> + for (i = 0; i < count; i++) {
> + struct led_classdev *led_cdev = priv->monochromatics[i];
> +
> + /* Make the sysfs of the monochromatic LED read-only */
> + mutex_lock(&led_cdev->led_access);
> + led_sysfs_disable(led_cdev);
> + mutex_unlock(&led_cdev->led_access);
> +
> + /* Restore sysfs access when the multicolor LED is released */
> + devm_add_action_or_reset(dev, restore_sysfs_access, led_cdev);
> + }
> +
> + 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@...phandler.com>");
> +MODULE_DESCRIPTION("multi-color LED group driver");
> +MODULE_LICENSE("GPL");
> +MODULE_ALIAS("platform:leds-group-multicolor");
> --
> 2.25.1
>
--
Lee Jones [李琼斯]
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