Intel Lunar Lake Graphics Introducing "CMRR" Adaptive VRR Feature

A new feature coming to next-generation Intel graphics display hardware has been revealed in new open-source Linux graphics driver patches: CMRR as an extension of the existing adaptive-sync variable rate refresh (VRR) functionality.

Intel CMRR is a new display feature coming for offering the latest adaptive sync / VRR capabilities. The open-source Linux graphics driver code has CMRR gated as being an Intel display version 20 feature. Display version 20 is to be found with Lunar Lake Xe2 integrated graphics. It's also possible this CMRR feature will be found with other hardware such as next-generation discrete graphics.

The Intel Linux graphics driver patches posted today simply describe CMRR as:

"CMRR is a display feature that uses adaptive sync framework to vary Vtotal slightly to match the content rate exactly without frame drops. This feature is a variation of VRR where it varies Vtotal slightly (between additional 0 and 1 Vtotal scanlines) to match content rate exactly without frame drops using the adaptive sync framework."

In going through the code, the CMRR feature appears to stand for Content Match Refresh Rate. CMRR in turn is making the existing variable refresh rate support "legacy VRR". With CMRR being tied to Intel display version 20 hardware and newer, this support doesn't work with existing Intel hardware.

The CMRR enablement code for the i915 kernel driver is out for review on intel-gfx as the public mailing list for the Intel Linux kernel graphics driver. Great as always seeing Intel's timely open-source Linux driver enabling work.