As it turns out, there is a chip on every laptop's display assembly. They control timing of pixel signals. Timing CONtrol, TCON chip.
I've noticed significant changes for me around 2019, and look at this industry news.
SAN JOSE, Calif. — (BUSINESS WIRE) — May 8, 2018 — Parade Technologies, Ltd. (Taiwan OTC: 4966.TWO), a leading high-speed interface, video display, and touch controller IC supplier, today announced a new highly-integrated eDP Timing Controller (Tcon) embedded driver (TED) IC developed for thin-profile LCD display panels. The TC3210 provides a single chip display driver solution to replace the traditional eDP Tcon mated up with separate source driver chips. The TC3210 was developed for Chip-on-Glass (COG) applications to support the new generation of sleek LCD panel assemblies.
Link: source
This is the chip they announced in 2018: https://www.paradetech.com/products/tc3210/
It has on-chip advanced processing of all sorts, including dithering!
Advanced Video Processing
Color Engine, FRC, and programmable Gamma Correction
CrystalFree™ technology, no external timing reference needed
Programmable BIST and aging patterns
Parade’s exclusive Smart-Backlight™ dynamic backlight control for color and power optimization
Media optimized playback modes
VESA® Adaptive-Sync
eDP DRR/nvDPS/sDRRS power saving modes
ASSR display authentication support
How can one find out what chip is on the display, and are display more or less interchangeable? e.g. a panel with a safe TCON chip could be a drop in replacement for an unsafe one? All this seems tightly controlled and proprietary.
At least, this one ancient chip appears to be programmable, as an example. Therefore, we should find out how to program the chip directly. Perhaps this is why OS/driver changes often changes the usability of the screen, it is not just the OS/GPU stack, the driver must also program the TCON chip correctly?