Screen is shifted a couple of pixels down

#1

Hi there, I m using a waveshare 3.5 inch screen 640x480 together with my radxa zero 4gb/32gb emmc.
I m running the official debian image and as you can see my screen is shifted down a couple of pixels. (Notice the blue pixels above the xfc panel as well as the bottom taskbar that is cut a couple of pixels)

IMG_20230117_131651
IMG_20230117_131651.jpg2320×1736 2.08 MB
IMG_20230117_131618
IMG_20230117_131618.jpg2320×1736 1.73 MB

The resolution seems to be correctly detected. How can I solve this?

EDIT: Solved this. this is how:
Followed the guide to manually set the resolution from here, more specifically step 3.
Instead of using cvt or gtf to calcualte modeline, use this online tool. Input the resolution and refresh rate of screen and THICK Image margin (to correct overscan). Then copy the modelin in the file as per the guide and reboot.
It worked for me, tested on armbian jammy. Will test on debian as well.

Inspired from this post: Debian Buster: HDMI Output Shifted Down

#2

In case it helps anyone else, I had a similar problem with a different HDMI display, a 5" with 800x480 resolution. For my application, I was using DRM rather than Xorg/Wayland for display rendering, so I didn’t have the option of using a custom modeline. I ended up addressing the problem by specifying a custom EDID with a kernel boot parameter, overriding the display’s reported EDID. More on that here.

#3

Solved this see EDIT and comment of @theophile