Intel is improving its Content Match Refresh Rate (CMRR) feature with the upcoming Linux 7.4 kernel, aiming to eliminate stuttering and frame drops during video playback. The feature, introduced with the Xe2 Lunar Lake graphics hardware, precisely matches video frame rates, going beyond traditional Variable Refresh Rate (VRR) technology.
Intel engineer Mitul Golani noted that previous CMRR code was limited to embedded DisplayPort (eDP) and relied on estimations. The new patches address these shortcomings and introduce a DebugFS-based control system, with a user-space API planned for the future. Currently, CMRR support will be enabled by default for Intel Display IP version 30 and newer – corresponding to Xe3/Panther Lake and newer hardware.
The DebugFS control allows users to specify a target refresh rate in milli-hz and video timing denominator. This provides granular control over CMRR behavior. The changes are part of a larger pull request of Intel kernel graphics driver material destined for Linux 7.4, which also includes adaptations to DG2 multi-protocol PLL code, DP-HDMI fixes, and other code cleanups. Additional features are expected to be added before the Linux 7.4 merge window in late October. Intel first began working on CMRR functionality in 2023, ahead of the Lunar Lake launch, but full utilization under Linux is only now becoming possible.
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