Screen turns off but backlight stays on

[marcx28]

I am using a Raspberry Pi 4 with Raspberry Pi OS 12 (Bookworm). The screen turns off but the backlight stays on. Do you have any idea how to prevent this?

Configuration:

{
	module: "MMM-Pir",
	position: "top_bar",
	config: {
		debug: true,
		delay: 5 * 1000,
		mode: 10,
		pir_mode: 1,
		displayCounter: false,
		displayLastPresence: false,
		lastPresenceTimeFormat: "LL H:mm",
		pir_gpio: 15,
		wrandrForceRotation: "270",
		touchMode: 0
	}
}

Changing to dtoverlay=vc4-fkms-v3d in /boot/firmware/config.txt as stated in the read me did not work for me because FKMS is deprecated in Bookworm.

[marcx28]

In case anyone has the same issue, this fixed my problem:

1. Add vc4.force_hotplug=1 to the end of the existing line in /boot/firmware/cmdline.txt. Don't make a new line.
2. Reboot

See more here