Turn Official Raspberry Pi 7" Touchscreen Display Off / On

[Vito303]

Describe the bug
Upgrade from 5.15.32-v8+ to 5.15.56-v8+ causes vcgencmd display_power does not work anymore.

To reproduce
sudo vcgencmd display_power 0
returns
display_power=-1
Does not affect on display.

Expected behaviour
sudo vcgencmd display_power 0
normal returns
display_power=0
The display is then turned off.

Actual behaviour
Does not affect on display. Echos 'display_power=-1' in terminal.

System

System Information

Raspberry Pi 3 Model B Rev 1.2
PRETTY_NAME="Debian GNU/Linux 11 (bullseye)"
NAME="Debian GNU/Linux"
VERSION_ID="11"
VERSION="11 (bullseye)"

Raspberry Pi reference 2022-04-04
Generated using pi-gen, https://github.com/RPi-Distro/pi-gen, 27a8050c3c06e567c794620394a8c2d74262a516, stage4

Linux aftNew 5.15.56-v8+ #1575 SMP PREEMPT Fri Jul 22 20:31:26 BST 2022 aarch64 GNU/Linux
Revision : a02082
Serial : 00000000ef3ffb27
Model : Raspberry Pi 3 Model B Rev 1.2
Throttled flag : throttled=0x20000
Camera : supported=0 detected=0, libcamera interfaces=0

Videocore information

Aug 9 2022 13:46:06
Copyright (c) 2012 Broadcom
version 273b410636cf8854ca35af91fd738a3d5f8b39b6 (clean) (release) (start)

[mickym2]

I have the same problem since the last kernel update on my Raspberry Pi4 4Gb.
vcgencmd display_power 0

returns
display_power=1

I have not a touchscreen but a normal monitor attached to the HDMI port and switched this off and on with my IoT system and this does no longer work.

Here are my specs:
uname -a Linux MWHome2 5.15.56-v8+ #1575 SMP PREEMPT Fri Jul 22 20:31:26 BST 2022 aarch64 GNU/Linux

[6by9]

vcgencmd issues commands to the firmware.
Bullseye has always used the vc4-kms-v3d driver, where all displays are controlled by the Linux kernel, and the firmware has no involvement. vcgencmd display_power will therefore do nothing.

[Blackbox-git]

I have the same issue with my Raspberry Pi 2B on a normal HDMI-Screen.

sudo vcgencmd display_power 0

returns
display_power=1

sudo vcgencmd display_power 0 0

returns
display_power=0

But both dosent work for me. I have the issu since my last update.

uname -a
The Display don´t turn off. My System is:
`Linux DisplayPi 5.15.56-v7+ #1575 SMP Fri Jul 22 20:28:11 BST 2022 armv7l GNU/Linux

vcgencmd version
Aug  9 2022 13:46:06
Copyright (c) 2012 Broadcom
version 273b410636cf8854ca35af91fd738a3d5f8b39b6 (clean) (release) (start)

[MichaIng]

vc4-kms-v3d driver, where all displays are controlled by the Linux kernel, and the firmware has no involvement

We have this reported as well and this was my first thought as well, but the docs don't state that it works with legacy graphics only and in our case downgrading to one of the last Linux 5.10 commit solved it. Of course some users switch to legacy or fKMS graphics driver. We'll do some tests to verify where it works and if there really something changed/broke with Linux 5.15.

[popcornmix]

vcgencmd display_power is not supported when using kms. Even if it had worked in the past, it's inherently unsafe to allow the firmware and the kernel to access the same hardware without knowledge that the other is also accessing it.

It looks like it stopped working with firmware commit:
platform: Block "vcgencmd display_power" if vc4-kms-v3d is enabled

so it was completely intentional. What needs to be done is to work out the correct linux side way of achieving what you want.

If you are booting to desktop then perhaps:
xset dpms force on
xset dpms force off

[popcornmix]

See here for context

[mickym2]

If this behavior is intended and the feature or the usage of vcgencmd display_power will never come back, I found a workaround - but it is more complicated to implement - and I have not really an understanding - what happens in the background.

I dont understand the security risk - why the functionality of vcgencmd display_power has been turned off - but it makes no sense to explain this to me, as I have not enough background knowledge to understand.,

So here is my procedure:
When a desktop is running and you want to switch of the display - I first modified the logon profile of the pi - for other users - pi seems to have the correct rights to disable some right issues. At least it is necessary - if switching off the display should also work remotely.

So those 2 commands have to be executed once - after each reboot of the machine:

export DISPLAY=:0.0
xhost +

if you dont export the DISPLAY variable - then you need really perform the commands locally on the machine. The export is necessary that you can remotely switch the display off and on over ssh. The xhost command is not necessary if only pi user use the commands (it seems this user has the necessary rights). To allow other users to use the command below - you need to disable the access control.

xhost + will generate the following output:
access control disabled, clients can connect from any host

You are then able to switch each HDMI port indivdually (i.e HDMI-1) on or off:

Switch display off:
xrandr --output HDMI-1 --off

Switch display on:
xrandr --output HDMI-1 --auto

[fire1ce]

+1 following

[wuast94]

+1 following

[rcarmo]

Also looking into this. I can't reliably control the official 7" display backlight on or off. Worse, using vcgencmd display_power 0 now seems to also disable the touchscreen.

[6by9]

I can't reliably control the official 7" display backlight on or off

What commands are you using?

I don't have a panel set up here, but backlight should be controllable through nodes under /sys/class/backlight, but I forget the full path used
sudo ch -c 'echo 0 > /sys/class/backlight/10-0045/rpi_touchscreen_attiny/brightness
(0 = off, with range up to 255)

sudo sh -c 'echo 1 > /sys/class/backlight/10-0045/rpi_touchscreen_attiny/bl_power'
1 for on, 0 for off.

Worse, using vcgencmd display_power 0 now seems to also disable the touchscreen.

As already stated above, vcgencmd display_power is incompatible with using vc4-kms-v3d and should not be used. IIRC it has already been blocked for HDMI, but may have been missed for DSI. Do not expect it to be coming back.