vcgencmd display_power 0 does not turn off screen after updating Raspberry Pi OS about userland HOT 6 CLOSED

See comment from JamesH65. "vcgencmd display_power 0" is only supported by the legacy FKMS display stack (vc4-fkms-v3d). The default is now KMS (vc4-fkms-v3d)

Use the xset dpms commands to control display power with KMS
https://www.computerhope.com/unix/uxset.htm

from userland.

See also this forum post. https://forums.raspberrypi.com/viewtopic.php?p=2036401&hilit=display_power#p2036401

from userland.

It sounds like you have started using the KMS driver, having moved from either the FKMS or the legacy graphics stack. That requires using the standard Linux command for turning displays on and off, not vcgencmd

from userland.

If that is the case, then I did not do this switch intentionally. The only change I did, before things got broken, was to run sudo apt update && sudo upgrade -y. What standard Linux command would you recommend, as replacement for the vcgencmd? I use the LCD screen on my smart mirror, and I just need to be able to turn it on/off when needed, through CLI.

from userland.

I just did a fresh reinstall of Raspberry Pi OS and installed the new updates on another rpi . Then I tested turning off the screen with vcgencmd display_power 0, bot same issue. Screen is still powered on!

Can anyone try reproducing these on their rpi?

from userland.

Thanks for helping out! I managed to turn the screen off/on with xset and xrandr, sharing details below so other users can find it later.

# tell xset which display to use
export DISPLAY=:0

# xandr turn off
xrandr --output HDMI-1 --off

# xandr turn on
xrandr --output HDMI-1 --auto

# xset turn off
xset dpms force off

# xset turn on
xset dpms force on

Important note: Screen Blanking must be enabled if using xset, otherwise you will see error saying "server does not have extension for DPMS option", ref https://forums.raspberrypi.com/viewtopic.php?t=277548

from userland.