[samsung-serranove] Plasma Mobile: screen flipped/mirrored

Describe your issue

What's the expected behaviour?

Normal screen.

What's the current behaviour?

The screen is horizontally flipped/mirrored.

How to reproduce your issue?

It's like this on first boot right after installation/flashing.

What device are you using?

samsung-serranove

On what postmarketOS version did you encounter the issue?

• edge (master branch)
• v21.06
• v21.12

On what environment did you encounter the issue?

Phone environments

• Phosh
• Plasma Mobile
• Sxmo (Wayland/Sway)

Other

• No environment
• GNOME
• KDE Plasma
• Kodi
• MATE
• Shelli
• Sway
• Weston
• Xfce4
• fbkeyboard
• i3wm
• Sxmo (Xorg/Dwm)

How did you get postmarketOS image?

• from https://images.postmarketos.org
• I built it using pmbootstrap
• It was preinstalled on my device

What's the build date of the image? (in yyyy-mm-dd format)

2021-12-12

Additional information

I expect this to be specific to samsung-serranove.

Its screen seems to be wired like this. We handle this by adding a reflect_x to the video parameter in the boot cmdline of the deviceinfo file (link). This works generally well.

It also worked for Plasma Mobile so far. Although this flipping/mirroring did happen after automatic screen rotation before. Now after some upgrade recently it's like this permanently.

I had a try by removing the reflect_x from cmdline and creating a new initramfs but that didn't help. The boot screen was mirrored, still Plasma Mobile remained flipped/mirrored as well. It seems to hande it independently.

I looked for a flipping option in the Settings -> Displays, in kscreen-doctor and in folder ~/.local/share/kscreen/. I see options for rotation and scale but not for flipping/mirroring.

Does anyone has an idea how to flip/mirror a screen in Plasma Mobile? If so, we can include that in a config file and install it with the device package.