I have been trying to get a 4" LCD touchscreen (allegedly a waveshare 4inch HDMI LCD device, 800x480 + XPT2046 controller, but no branding, so who knows) working with a pi 3b to no avail. The problem I'm having is easier to show than to explain, so image attached.
For the sake of explanation, what it looks like is that the scanlines are 90 degrees of where they should be, but somehow the net area of the screen is taken up. Thus, there are a bunch of black lines between the parts with image data, and everything is just plain manky but you can see the image is "there" in the mess.
I have used both the driver installer and the image from the waveshare github page, no effect. I have also read through this rather scathing but useful blog post but that did not manage to help either. I can get the image rotated 90 degrees so it's not as bad, but the missing horizontal data is still missing, and I am not sure what the problem is primarily because I don't seem to be able to find others having this problem (most likely I'm describing the problem incorrectly, hence the image).
Also, screen is confirmed working correctly because I can use an SD card that has some massaged code on it and it works as expected. Unfortunately, I cannot seem to extract the information from the working image owing to a rather massive amount of undocumented hacking on that image by not-me. Hornets nest that one.
Thanks in advance for any help, greatly appreciated.