Re: [PATCH V4] leds: rgb: leds-group-multicolor: Implement default-intensity

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] The `default-intensity` property read from individual monochromatic LED nodes is applied to the multicolor group without rescaling, causing incorrect brightness calculations.
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--- Patch [1]: [PATCH V4] leds: rgb: leds-group-multicolor: Implement default-intensity ---
commit 13399f1aaceaf09afa7e252e35000d7d61ab1925
Author: Stefan Wahren <[email protected]>

leds: rgb: leds-group-multicolor: Implement default-intensity

This commit introduces support for the default-intensity property during
boot for LED multicolor groups. If the property is missing, the code falls
back to the previous behavior of configuring the sub-LED intensity to its
maximum.

> diff --git a/drivers/leds/rgb/leds-group-multicolor.c b/drivers/leds/rgb/leds-group-multicolor.c
> --- a/drivers/leds/rgb/leds-group-multicolor.c
> +++ b/drivers/leds/rgb/leds-group-multicolor.c
> @@ -108,8 +108,10 @@ 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;
> +		ret = device_property_read_u32(led_cdev->dev, "default-intensity",
> +					       &subled[i].intensity);
> +		if (ret || subled[i].intensity > max_brightness)
> +			subled[i].intensity = max_brightness;

[Severity: Medium]
Does this logic properly scale the intensity when the individual LEDs in the
group have different maximum brightness values?

If a multicolor group consists of LEDs with vastly different maximum brightness
capabilities (like a GPIO LED maxing at 1 and a PWM LED maxing at 255), the
overall group max_brightness will evaluate to 255.

When reading the default-intensity from the device tree, the value is typically
specified on the scale of the individual sub-LED's max brightness. If this
value is assigned directly to subled[i].intensity without being scaled up to
the group's max_brightness, the sub-LED might be initialized with only a tiny
fraction of its intended intensity, often resulting in the LED being completely
unlit instead of at the requested intensity.

>  	}
>  
>  	/* Initialise the multicolor's LED class device */

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Sashiko AI review · https://sashiko.dev/#/patchset/[email protected]?part=1