Re: [PATCH v5 08/14] mfd: lm3533: Convert to use OF bindings

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] The `default-brightness` property is read from the Device Tree as a `u32` without being clamped to `LM3533_BL_MAX_BRIGHTNESS` (255).
--

commit ea75baf449ff637e79d3393f0fdd68b3fcf947de
Author: Svyatoslav Ryhel <clamor95@gmail.com>

mfd: lm3533: Convert to use OF bindings

This commit removes platform data support and transitions the driver to use
Device Tree bindings for its configuration.

> diff --git a/drivers/video/backlight/lm3533_bl.c b/drivers/video/backlight/lm3533_bl.c
> index 9ef171d3aaeab..2c24647fc17a4 100644
> --- a/drivers/video/backlight/lm3533_bl.c
> +++ b/drivers/video/backlight/lm3533_bl.c

[ ... ]

> @@ -292,13 +291,21 @@ static int lm3533_bl_probe(struct platform_device *pdev)
>  	bl->cb.id = lm3533_bl_get_ctrlbank_id(bl);
>  	bl->cb.dev = NULL;			/* until registered */
>  
> +	name = devm_kasprintf(&pdev->dev, GFP_KERNEL, "%s-%d",
> +			      pdev->name, pdev->id);
> +	if (!name)
> +		return -ENOMEM;
> +
> +	device_property_read_u32(&pdev->dev, "default-brightness",
> +				 &default_brightness);
> +
>  	memset(&props, 0, sizeof(props));
>  	props.type = BACKLIGHT_RAW;
>  	props.max_brightness = LM3533_BL_MAX_BRIGHTNESS;
> -	props.brightness = pdata->default_brightness;
> +	props.brightness = default_brightness;

[Severity: Medium]
Should default_brightness be clamped to LM3533_BL_MAX_BRIGHTNESS before being
assigned to props.brightness?

The transition to Device Tree bindings introduces reading default-brightness
as a u32. In the previous platform data implementation, default_brightness
was a u8, which inherently restricted it to a 0-255 range.

If a Device Tree provides a value greater than 255, it will be implicitly
truncated to an 8-bit unsigned integer when passed to the hardware writing
functions (for instance, 256 would wrap around to 0). This would cause the
backlight to turn off instead of setting it to the expected maximum brightness.

Does it make sense to clamp default_brightness similar to how led-max-microamp
is clamped later in this function?

> -	bd = devm_backlight_device_register(&pdev->dev, pdata->name,
> -					pdev->dev.parent, bl, &lm3533_bl_ops,
> -					&props);
> +
> +	bd = devm_backlight_device_register(&pdev->dev, name, &pdev->dev,
> +					    bl, &lm3533_bl_ops, &props);

[ ... ]

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260617080031.99156-1-clamor95@gmail.com?part=8