News Linux GPU Driver for Intel Lunar Lake Chip Adds CMRR Variable Refresh Rate Feature

[Admin]

CMRR is a variation of variable refresh rate (VRR) technology that's coming with Lunar Lake's integrated graphics.

Linux GPU Driver for Intel Lunar Lake Chip Adds CMRR Variable Refresh Rate Feature : Read more

 

[edzieba]

This article seems to be incredibly confused over terminology.:

DP Adaptive Sync: the eDP (embedded DisplayPort) function to change display update rate as needed to reduce power by allowing panels to self-refresh (PSR) or just to vary refresh rate within the display's regular refresh capaciblity.

'FreeSync': AMD's initial use of DP Adaptive Sync to (somewhat) match the capabilities of GSync. It's roots in eDP are why the early Fresync demos were with laptops using eDP rather than with external monitors.

GSync: Nvidia's VRR implementation predating FreeSync, and not based on eDP Adaptive Sync but instead a clean-sheet implementation. Also refers to the FPGA modules acting as panel controllers to implement this protocol, but later monitors have had 3rd party controllers that also implement the same protocol.

Variable Refresh Rate: general heading for all variable refresh rate techniques and protocols, not any specific technique or protocol.

OK terminology out of the way. What is going on here with Intel's CMRR is nothing to do with VRR for gaming. Instead, this is an implementation of good ol' eDP Adaptive Sync in order to match panel refresh rate to (or to an integer multiple of) the framerate of media being played back. e.g. a 60 FPS video would drive the display at 60Hz, a 24 FPS video would drive it at 24Hz (or or 48Hz or 96Hz), etc. More specifically, this is for dealing with the weird 23.97 FPS and 29.97 FPS media (due to legacy colour subccarrier tomfoolery with NTSC) that needs only slight variance in update rate to remain in sync with audio. Adding and removing lines from the frame (the VTotal modification) without modifying VF allows for that slight change in update rate to keep things in sync.