There is no HDMI output when TV turns on later than LibreELEC

If my TV is off when LibreELEC starts up then there is no HDMI signal when I turn on the TV.

I have not been able to solve the problem, only assign a key on the remote control to restart the mini PC with the TV on.

Does anyone know how to solve this problem other than restarting the mini PC with the TV on?

Notes:

- Mini PC with Intel i5-5257U hardware (and with Iris Graphics 6100) and two HDMI outputs.

- LibreELEC stable 9.2.6 running 24/7 as a server with daily scheduled restart. Running services: SSH, SFTP, SAMBA (read-only services), FTP, TigerVNC, tvheadend, zerotier-one, syncthing, oscam, portainer, and docker.

Quote from Klojum

Turn on the TV first, then the RPi... LibreELEC needs to do a HDMI-handshake, which isn't possible when the TV is off.

Also, read here: "No signal" on TV with Raspberry Pi 4, after LibreELEC logo.

"Turn on the TV first" - Not possible, the PC works 24/7. It is a TV server (tvheadend), multimedia server (Samba and FTP) and automatic smartphones backup server (syncthing) for my house and the houses of my relatives (zerotier-one). It reboot at dawn when all the TVs are off.

"then the RPi ..." - It is not an RPi, it is an x86-64 PC, the solutions in the link do not work.

Note.- When the LibreELEC server starts up with the TV turned off, a VNC session (tigerVNC) can be started but always in "virtual screen" 1024x768p60Hz mode and no other resolution can be chosen. When the TV is on and LibreELEC is working fine, then multiple resolutions can be chosen. I manage all LibreELEC and CoreELEC devices from my smartphone. With CoreELEC and ARM Amlogic processors as a server I never had any problems.

When LibreELEC started with TV off:

LibreELEC:/etc/X11 # xrandr -q
Screen 0: minimum 8 x 8, current 1024 x 768, maximum 32767 x 32767
HDMI1 disconnected primary (normal left inverted right x axis y axis)
HDMI2 disconnected (normal left inverted right x axis y axis)
VIRTUAL1 disconnected (normal left inverted right x axis y axis)


When LibreELEC started with TV off and after TV is started:

LibreELEC:/etc/X11 # xrandr -q
Screen 0: minimum 8 x 8, current 1024 x 768, maximum 32767 x 32767
HDMI1 connected primary (normal left inverted right x axis y axis)
1920x1080     60.00 +  50.00    59.94    30.00    25.00    24.00    29.97    23.98
1920x1080i    60.00    50.00    59.94
1280x1024     60.02
1360x768      60.02
1152x864      59.97
1280x720      60.00    50.00    59.94
1024x768      60.00
800x600       60.32
720x576       50.00
720x576i      50.00
720x480       60.00    59.94
640x480       60.00    59.94
720x400       70.08
HDMI2 disconnected (normal left inverted right x axis y axis)
VIRTUAL1 disconnected (normal left inverted right x axis y axis)

The command

/usr/bin/xrandr --output HDMI1 --mode 1920x1080 --rate 25

works inside SSH but not inside crontab.

Solved

During the LibreELEC installation I used the HDMI2 port of the PC. LibreELEC configured itself to boot on this port. A few days later I switched to the HDMI1 port and thereafter LibreELEC was unable to activate the TV when it was turned on later than LibreELEC.

Conclusion: LibreELEC configures itself to turn on the TV during the installation process.

More informationfor for x86_64 processors here EDID - LibreELEC.wiki.