Where can I find the documentation needed to operate the display controller?
Currently I’m just going off the u-boot driver, because I can’t seem to find formal documentation on it u-boot/drivers/video/eswin at u-boot-2024.01-EIC7X · eswincomputing/u-boot · GitHub
Have you checked EIC7700X Datasheet posted on Premier P550 WEB page?
Yes. It was only slightly helpful. It reads as more of a selling point of the display controller than a manual. At one point it makes references to registers but does not state where they are located. Luckily, this file does: u-boot/drivers/video/eswin/eswin_dc_reg.h at u-boot-2024.01-EIC7X · eswincomputing/u-boot · GitHub