DISPLAY REFRESH RATE SWITCHING (DRRS)(9)

💖 Display Refresh Rate Switching (DRRS) 💖

okay bestie, welcome to the Display Refresh Rate Switching (DRRS) page, section 9 of the Kernel API Manual — and it’s giving “power saving but make it display tech.” 🫶

Display Refresh Rate Switching (DRRS) is a power conservation feature which enables switching between low and high refresh rates, dynamically, based on the usage scenario. This feature is applicable for internal panels. ✨

Indication that the panel supports DRRS is given by the panel EDID, which would list multiple refresh rates for one resolution. 👑

DRRS is of 2 types — static and seamless. Static DRRS involves changing refresh rate (RR) by doing a full modeset (may appear as a blink on screen) and is used in dock-undock scenario. Seamless DRRS involves changing RR without any visual effect to the user and can be used during normal system usage. This is done by programming certain registers. 💅

Support for static/seamless DRRS may be indicated in the VBT based on inputs from the panel spec. 🎀

DRRS saves power by switching to low RR based on usage scenarios. 🍓

The implementation is based on frontbuffer tracking implementation. When there is a disturbance on the screen triggered by user activity or a periodic system activity, DRRS is disabled (RR is changed to high RR). When there is no movement on screen, after a timeout of 1 second, a switch to low RR is made. ⭐

For integration with frontbuffer tracking code, intel_drrs_invalidate and intel_drrs_flush are called. 🦋

DRRS can be further extended to support other internal panels and also the scenario of video playback wherein RR is set based on the rate requested by userspace. 🌈

✨ SEE ALSO ✨

• Kernel file ./drivers/gpu/drm/i915/display/intel_drrs.c
• intel_drrs_activate(9)
• intel_drrs_deactivate(9)
• intel_drrs_invalidate(9)
• intel_drrs_flush(9)
• intel_drrs_crtc_init(9)

and that’s the footer, bestie: source/version ./drivers/gpu/drm/i915/display, dated October 2026. mwah 💜