linux-kernel - Re: [PATCH v4 6/6] leds: Add a multicolor LED driver to group monochromatic LEDs

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Date:   Fri, 7 Oct 2022 19:31:56 +0300
From:   Andy Shevchenko <andy.shevchenko@...il.com>
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, bjorn.andersson@...aro.org,
        jacek.anaszewski@...il.com, linux-leds@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 6/6] leds: Add a multicolor LED driver to group
 monochromatic LEDs

On Fri, Oct 7, 2022 at 5:56 PM Jean-Jacques Hiblot
<jjhiblot@...phandler.com> wrote:
>
> 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.

...

> +config LEDS_GRP_MULTICOLOR
> +       tristate "Multi-color LED grouping support"

> +       depends on OF

But there is no compilation requirement for that.
If you want to tell that this is functional requirement, you may use

    depends on COMPILE_TEST || OF

pattern

...

> +       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;

Perhaps keep it before previous line?

> +       count = 0;
> +       max_brightness = 0;
> +       for (;;) {
> +               struct led_classdev *led_cdev;
> +
> +               led_cdev = devm_of_led_get_optional(dev, count);

> +               if (!led_cdev)

> +                       /* Reached the end of the list */
> +                       break;

This will require {} according to the style guide. Maybe move the
comment on top of the if (!led_cdev) check?

> +               if (IS_ERR(led_cdev))
> +                       return dev_err_probe(dev, PTR_ERR(led_cdev),
> +                                            "Unable to get led #%d", count);

I would check for an error first, this is a common pattern in the Linux kernel.

> +               count++;
> +
> +               priv->monochromatics = devm_krealloc_array(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_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;
> +               /* configure the LED intensity to its maximum */
> +               subled[i].intensity = max_brightness;
> +       }
> +
> +       /* 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 = dev_fwnode(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.\n",
> +                       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 */
> +               led_cdev->flags |= LED_SYSFS_DISABLE;
> +       }
> +
> +       return 0;
> +}

-- 
With Best Regards,
Andy Shevchenko