Variable Refresh Rate "VRR" Target Limiter Proposed For Linux Graphics Drivers
([Linux Kernel] 31 Minutes Ago
VRR Target Rate Limiter)
- Reference: 0001659501
- News link: https://www.phoronix.com/news/VRR-Target-Rate-Limiter-uAPI
- Source link:
A new proposal being discussed is introducing a Linux user-space API to be able to specify frame rate targets for Variable Refresh Rate (VRR) handling on the Linux desktop.
Nicolas Frattaroli of Collabora authored a proposal and a set of 25 patches seeking comment on a VRR target rate limiter interface. This would let user-space games/applications/compositors communicate a constrained range where VRR should target or a fixed target. Plus it adds a new Quick Media Switching "QMS" target.
Frattaroli describes this VRR target rate limiter functionality as:
"This series defines a proposed new userspace API for specifying frame rate targets for variable refresh rate (VRR) mechanisms. This includes specifying both a constrained range in which VRR should operate, as well as a fixed target, and a new connector property for QMS (Quick Media Switching).
The reason for wanting such an uAPI is mainly to avoid the imperfection of the real world. By constraining VRR to a limited range or a fixed point entirely, we get the benefits of judder-free (or low-latency) presentation for content within an expected range of frame rates, without dipping into ones that cause visible brightness flicker. The addition of QMS furthermore allows the connector to signal an upcoming rate change ahead of time for media playback scenarios, such that advanced processing algorithms in e.g. TVs don't have to be disabled to meet the need to be able to present at full rates with no notice."
The patches implement "Game Mode" VRR for the HDMI state helpers and also implement it for the Rockchip RK3588 driver.
The topic was also [1]covered at this year's Display Next Hackfest.
The RFC kernel patches for those interested can be found on [2]the dri-devel list . There is also a [3]vrr-limiter Git branch containing the VRR limiter patches against the Wayland's reference Weston compositor.
[1] https://gitlab.freedesktop.org/-/project/2891/uploads/9db8886701e2598271a8c4c6dc4dc2b1/display_next_hackfest_2026.pdf
[2] https://lore.kernel.org/dri-devel/20260921-vrr-limiter-uapi-v1-0-2fcd7d011646@collabora.com/
[3] https://gitlab.freedesktop.org/CounterPillow/weston/-/commits/vrr-limiter?ref_type=heads
Nicolas Frattaroli of Collabora authored a proposal and a set of 25 patches seeking comment on a VRR target rate limiter interface. This would let user-space games/applications/compositors communicate a constrained range where VRR should target or a fixed target. Plus it adds a new Quick Media Switching "QMS" target.
Frattaroli describes this VRR target rate limiter functionality as:
"This series defines a proposed new userspace API for specifying frame rate targets for variable refresh rate (VRR) mechanisms. This includes specifying both a constrained range in which VRR should operate, as well as a fixed target, and a new connector property for QMS (Quick Media Switching).
The reason for wanting such an uAPI is mainly to avoid the imperfection of the real world. By constraining VRR to a limited range or a fixed point entirely, we get the benefits of judder-free (or low-latency) presentation for content within an expected range of frame rates, without dipping into ones that cause visible brightness flicker. The addition of QMS furthermore allows the connector to signal an upcoming rate change ahead of time for media playback scenarios, such that advanced processing algorithms in e.g. TVs don't have to be disabled to meet the need to be able to present at full rates with no notice."
The patches implement "Game Mode" VRR for the HDMI state helpers and also implement it for the Rockchip RK3588 driver.
The topic was also [1]covered at this year's Display Next Hackfest.
The RFC kernel patches for those interested can be found on [2]the dri-devel list . There is also a [3]vrr-limiter Git branch containing the VRR limiter patches against the Wayland's reference Weston compositor.
[1] https://gitlab.freedesktop.org/-/project/2891/uploads/9db8886701e2598271a8c4c6dc4dc2b1/display_next_hackfest_2026.pdf
[2] https://lore.kernel.org/dri-devel/20260921-vrr-limiter-uapi-v1-0-2fcd7d011646@collabora.com/
[3] https://gitlab.freedesktop.org/CounterPillow/weston/-/commits/vrr-limiter?ref_type=heads