RPi 4 with Ubuntu 19.10 not displaying on HDMI

[rogeriod]

I have a RPi 4 (4Gb) with Ubuntu 19.10 + Desktop Ubuntu running and displaying fine over HDMI when connected to a TV.

Today I bought an external monitor and connected the RPi to it. Monitor says that HMDI is connected but that is receiving no signal.

I have another RPi 4 (2 Gb) running Raspian Buster as a home webserver. I've connected this RPi to the external monitor and got the same outcome. After googling the issue, I have changed the /boot/config.txt to have uncommented:

hdmi_safe=1
hdmi_force_hotplug=1
config_hdmi_boost=9

Did a reboot and HDMI works fine on the external monitor.

The question now is ... on the RPi4 with Ubuntu, there is no /boot/config.txt file.

How do I enable/force/boost the HDMI signal?

[aBUGSworstnightmare]

Tested some display stuff (my DPI to LVDS boards) with ubuntu mate. As far as I remember there should be a config.txt somewhere

On ubuntu I would look for /boot/firmware/usercfg.txt as I think thats the one you need to edit (but not sure as I've not used 19.10 yet)

[rogeriod]

ubuntu@ubuntu:/boot/firmware$ cat usercfg.txt
# Place "config.txt" changes (dtparam, dtoverlay, disable_overscan, etc.) in
# this file. Please refer to the README file for a description of the various
# configuration files on the boot partition.

The usrcfg.txt is blank and can be edited - shoud I use exactly the same parameters on this file?

hdmi_safe=1
hdmi_force_hotplug=1
config_hdmi_boost=9

[rogeriod]

OK, I've fixed the monitor hdmi issue!

The usercfg.txt below is specific to the RPi4 port 0 and the monitor I am using.

ubuntu@ubuntu:/boot/firmware$ cat usercfg.txt
# Place "config.txt" changes (dtparam, dtoverlay, disable_overscan, etc.) in
# this file. Please refer to the README file for a description of the various
# configuration files on the boot partition.
hdmi_force_mode=1
hdmi_group:0=2
hdmi_mode:0=39

Based on:
https://www.raspberrypi.org/documentati ... t/video.md
https://www.raspberrypi.org/documentati ... itional.md