A recent graphics driver update to Intel’s upcoming Lunar Lake CPU adds CMRR to the chip’s integrated graphics (via Phoronix). CMRR, short for Content Match Refresh Rate, is based on Variable Refresh Rate (VRR), the technology featured in Adaptive Sync, AMD FreeSync, and Nvidia G-Sync. This new feature could be a big deal for both Lunar Lake and future Intel GPUs that might also come with CMRR.
The drivers in question are Lunar Lake’s Linux GPU drivers and haven’t been officially announced — all we have to go on is this comment from the update itself:
“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.”
That’s not exactly a ton to go off of, unfortunately. However, Vtotal seems to be short for Vertical Total, which is a technical term associated with display technology. Basically, a higher Vertical Total means less strobe crosswalk (sometimes called ghosting). CMRR could be intended to reduce strobe crosswalk without impacting the framerate.
CMRR is exclusive to Intel GPUs with display version 20, which presumably will be present on Lunar Lake. However, it’s also possible that other Intel GPUs, such as Arc Battlemage discrete graphics cards, will have display version 20 and CMRR. For now we can only really speculate on what CMRR will actually do, how useful it will be, and what GPUs will get it.
That Lunar Lake’s drivers are getting this new feature nearly a year before the CPU is set to launch is a good sign. Lunar Lake is due in the second half of 2024, and a steady march of Linux updates to various apps and drivers indicates that progress on Lunar Lake must be going decently well.