Waveshare 7.9" HDMI help Rotate Screen - Using MoOde 9.0

[MonoBY]

A brand new article on raspberrypi.com describes how to rotate HDMI displays on Debian Bookworm based OS like Raspberry Pi OS and Moode. It focuses on their own 7" Raspberry Pi Touch Display but it should also work on other HDMI displays.

How to use the Raspberry Pi Touch Display
https://www.raspberrypi.com/news/how-to-use-the-raspberry-pi-touch-display/

Start at chapter "Change screen orientation", especially "Rotate screen without a desktop".

Code:

Rotate screen without a desktop

To set the screen orientation on a device that lacks a desktop environment, edit the /boot/firmware/cmdline.txt configuration file to pass an orientation to the system. Add the following line to cmdline.txt:

video=DSI-1:800x480@60,rotate=<rotation-value>

Replace the <rotation-value> placeholder with one of the following values, which correspond to the degree of rotation relative to the default on your display:

   0
   90
   180
   270

For example, a rotation value of 90 rotates the display 90 degrees to the right. 180 rotates the display 180 degrees, or upside-down.

If you need touch support, it becomes more complicated...