linux-kernel - Re: [PATCH] leds: group-multicolor: Add support for initial value.

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Message-ID: <20251119165109.GV1949330@google.com>
Date: Wed, 19 Nov 2025 16:51:09 +0000
From: Lee Jones <lee@...nel.org>
To: Martijn de Gouw <martijn.de.gouw@...drive-technologies.com>
Cc: Pavel Machek <pavel@...nel.org>, linux-leds@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] leds: group-multicolor: Add support for initial value.

On Tue, 11 Nov 2025, Martijn de Gouw wrote:

> It's possible to set a default state for leds in the dts with
> 'default-state', but this was not reflected when the LEDs are grouped.
> This patch adds support for keeping the default-state value.
> 
> Signed-off-by: Martijn de Gouw <martijn.de.gouw@...drive-technologies.com>
> ---
>  drivers/leds/rgb/leds-group-multicolor.c | 13 +++++++++++--
>  1 file changed, 11 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/leds/rgb/leds-group-multicolor.c b/drivers/leds/rgb/leds-group-multicolor.c
> index 548c7dd63ba1e..b3e46a51dfbc7 100644
> --- a/drivers/leds/rgb/leds-group-multicolor.c
> +++ b/drivers/leds/rgb/leds-group-multicolor.c
> @@ -69,6 +69,7 @@ static int leds_gmc_probe(struct platform_device *pdev)
>  	struct mc_subled *subled;
>  	struct leds_multicolor *priv;
>  	unsigned int max_brightness = 0;
> +	unsigned int default_brightness = 0;
>  	int i, ret, count = 0, common_flags = 0;
>  
>  	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
> @@ -96,6 +97,12 @@ static int leds_gmc_probe(struct platform_device *pdev)
>  
>  		max_brightness = max(max_brightness, led_cdev->max_brightness);
>  
> +		/* If any LED is on, set brightness to the max brightness.
> +		 * The actual brightness of the LED is set as intensity value.
> +		 */

I don't know this code well, but if no one complains, I can take your
word for this.

However, the comment needs changing to proper multi-line format.

        /*
         * This is the preferred style for multi-line
         * comments in the Linux kernel source code.
         * Please use it consistently.
         *
         * Description:  A column of asterisks on the left side,
         * with beginning and ending almost-blank lines.
         */

> +		if (led_cdev->brightness)
> +			default_brightness = max_brightness;
> +
>  		count++;
>  	}
>  
> @@ -109,14 +116,16 @@ static int leds_gmc_probe(struct platform_device *pdev)
>  
>  		subled[i].color_index = led_cdev->color;
>  
> -		/* Configure the LED intensity to its maximum */
> -		subled[i].intensity = max_brightness;
> +		/* Configure the LED intensity to its current brightness */
> +		subled[i].intensity = DIV_ROUND_CLOSEST(led_cdev->brightness * max_brightness,

How does this work?  Won't this value be huge?

> +							led_cdev->max_brightness);

Also we said we were going to set actual brightness with the intensity
in the comment above, but we appear to be using max_brightness again?

>  	}
>  
>  	/* Initialise the multicolor's LED class device */
>  	cdev = &priv->mc_cdev.led_cdev;
>  	cdev->brightness_set_blocking = leds_gmc_set;
>  	cdev->max_brightness = max_brightness;
> +	cdev->brightness = default_brightness;
>  	cdev->color = LED_COLOR_ID_MULTI;
>  	priv->mc_cdev.num_colors = count;
>  
> -- 
> 2.39.2
> 

-- 
Lee Jones [李琼斯]