linux-kernel - Re: [PATCH v4 1/2] backlight: Add Congatec Board Controller (CGBC) backlight support

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Message-ID: <a4edce66-d08a-4b82-9472-b22f2fdb34eb@bootlin.com>
Date: Sat, 29 Nov 2025 11:27:56 +0100
From: Thomas Richard <thomas.richard@...tlin.com>
To: petri.karhula@...atron.fi, Lee Jones <lee@...nel.org>,
 Daniel Thompson <danielt@...nel.org>, Jingoo Han <jingoohan1@...il.com>,
 Helge Deller <deller@....de>
Cc: linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org,
 linux-fbdev@...r.kernel.org
Subject: Re: [PATCH v4 1/2] backlight: Add Congatec Board Controller (CGBC)
 backlight support

On 11/27/25 4:21 PM, Petri Karhula via B4 Relay wrote:
> From: Petri Karhula <petri.karhula@...atron.fi>
> 
> This driver provides backlight brightness control through the Linux
> backlight subsystem. It communicates with the board controller to
> adjust LCD backlight using PWM signals. Communication is done
> through Congatec Board Controller core driver.
> 

[...]

> +		bl_data->current_brightness = reply_buf[0] & BLT_PWM_DUTY_MASK;
> +
> +		/* Verify the setting was applied correctly */
> +		if (bl_data->current_brightness != brightness) {
> +			dev_err(bl_data->dev,
> +				"Brightness setting verification failed\n");
> +			return -EIO;
> +		}

I'm still not really convinced by other error messages, but okay let's
keep them. Maybe add current and requested brightnesses in this message,
it could be useful for debugging.

	"Brightness setting verification failed (X instead of Y)"

Otherwise looks good to me. I will test your series

Reviewed-by: Thomas Richard <thomas.richard@...tlin.com>

Best Regards,
Thomas