linux-kernel - Re: [RESEND PATCH v3 4/4] leds: Add a multicolor LED driver to group monochromatic LEDs

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Date:   Sat, 17 Sep 2022 11:37:44 +0300
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Jean-Jacques Hiblot <jjhiblot@...phandler.com>
Cc:     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,
        linux-leds@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, sha@...gutronix.de
Subject: Re: [RESEND PATCH v3 4/4] leds: Add a multicolor LED driver to group
 monochromatic LEDs

On Sat, Sep 17, 2022 at 11:14 AM 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"
> +       help
> +         This option enables support for monochrome LEDs that are
> +         grouped into multicolor LEDs.

What will be the module name in case of "m" choice?

...

> +       struct led_mcg_priv *priv =
> +               container_of(mc_cdev, struct led_mcg_priv, mc_cdev);

One line?

...

> +               /*
> +                * Scale the intensity according the max brightness of the
> +                * monochromatic LED

Usually we put a grammar period at the end of sentences in multi-line comments.

> +                */

...

> +               actual_led_brightness = DIV_ROUND_CLOSEST(
> +                       mono->max_brightness * mc_cdev->subled_info[i].brightness,
> +                       mc_cdev->led_cdev.max_brightness);

Can you fix an indentation, so it won't leave the line ending by open
parenthesis? I believe with the help of a temporary variable it can be
easily achieved.

...

> +       for (;;) {
> +               struct led_classdev *led_cdev;

> +               led_cdev = devm_of_led_get(dev, count);

Why _of_ variant? Please, make this OF independent since it's
pretending to cover not only OF-based systems.


> +               if (IS_ERR(led_cdev)) {

> +                       /* Reached the end of the list ? */
> +                       if (PTR_ERR(led_cdev) == -ENOENT)
> +                               break;

Looks like the above needs an _optional() variant

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

...

> +               priv->monochromatics = devm_krealloc(dev, priv->monochromatics,
> +                                       count * sizeof(*priv->monochromatics),
> +                                       GFP_KERNEL);

This needs at minimum to use one of the helpers from overflow.h,
ideally you may implement devm_krealloc_array() as a suitable wrapper
for that.

> +               if (!priv->monochromatics)
> +                       return -ENOMEM;

...

> +       subled = devm_kzalloc(dev, count * sizeof(*subled), GFP_KERNEL);

NIH devm_kcalloc()

> +       if (!subled)
> +               return -ENOMEM;

--
With Best Regards,
Andy Shevchenko