Please check the versions of Linux kernel and Petitboot before setting ODROID-Vu8M, update firmware blobs if required.

Version of Petitboot must be v20220424 or later.

$ dpkg -s linux-image-4.19.219-odroid-arm64 | grep -i version
Version: 4.19.219-202204111511~focal

First, add panel value to Petitboot or U-Boot so it loads proper display configuration when OS starts.

• On the Petitboot

fw_setenv panel display_vu8m

• On the U-BOOT

setenv panel display_vu8m

And, It is necessary to add display_vu8m to the line starts with overlays= in config.ini to enable DSI port. The change will affect after rebooting.

$ vi /boot/config.ini 
[generic]
...
overlays="i2c0 i2c1 display_vu8m"
...

$ busybox vi /fat/config.ini
[generic]
...
overlays="i2c0 uart0 spi0 display_vu8m"
...

Open Settings → Displays, and change select the display orientation at Orientation.

In order to change the orientation of log in screen of Gnome Desktop, it's required to copy the monitor setup as well.

sudo cp ~/.config/monitors.xml /var/lib/gdm3/.config/
sudo reboot

The default oriention is portrait mode, you can change orientation to landscape.

$ adb remount
# busybox vi /fat/config.ini
...
###########################
# vu8m orientation
# ex) default portrait
# The screen is portrait and the HDMI port is to the top of screen.
# ro.surface_flinger.primary_display_orientation=ORIENTATION_0
# user_def_args="orientation=0"
#
# ex) default landscape
# The screen is landscape and the HDMI port is to the right of screen.
# ro.surface_flinger.primary_display_orientation=ORIENTATION_270
# user_def_args="orientation=5"
#
# ex) reverse portrait
# The screen is portrait and the HDMI port is to the left of screen.
# ro.surface_flinger.primary_display_orientation=ORIENTATION_180
# user_def_args="orientation=4"
#
# ex) reverse landscape
# The screen is landscape and the HDMI port is to the left of screen.
# ro.surface_flinger.primary_display_orientation=ORIENTATION_90
# user_def_args="orientation=3"

overlays="i2c0 uart0 spi0 display_vu8m"
user_def_args="orientation=5"
...

$ adb remount
$ adb shell
# busybox vi /vendor/default.prop
...
ro.surface_flinger.primary_display_orientation=ORIENTATION_270
...

You can use the ODROID-Vu8M for Dual display in the Android.