drm: allow disabling VRR on legacy surfaces - #2189
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Sorry, but this needs a rebase, before I can merge |
Legacy DRM does not expose the VRR_ENABLED property, so use_vrr currently returns UnknownProperty even when asked to disable VRR. This requires callers to check VRR support before requesting the inactive state, unlike the atomic backend. Treat use_vrr(false) as a successful no-op on legacy surfaces. Continue returning UnknownProperty when attempting to enable VRR. Tested: - cargo test --features test_all_features - cargo fmt --all -- --check Developed with AI assistance (OpenAI Codex); all changes have been reviewed and are understood by the author. Signed-off-by: Jim Witte <jim@thunderingbison.com>
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@Drakulix rebased onto current master and force-pushed the branch |
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Description
DrmSurface::use_vrrcurrently returnsUnknownProperty("VRR_ENABLED")for both enabling and disabling VRR when Smithay uses legacy DRM.The legacy backend does not support VRR and reports VRR as unsupported and disabled. The atomic backend treats an absent
VRR_ENABLEDproperty as an error only when VRR is being enabled.Change
Have
use_vrr(false)returnOk(())on the legacy backend while preserving the existing error foruse_vrr(true). This allows compositors to request the disabled state without first checking whether VRR is supported.A downstream workaround was proposed in pop-os/cosmic-comp#2884. COSMIC calls
use_vrr(false)while rendering, so the legacy backend's error can produce anUnknownProperty("VRR_ENABLED")warning every frame.Handling the disabled state in Smithay avoids requiring consumers to add a capability check and aligns the legacy behavior with the atomic backend.
Testing
cargo test --features test_all_featurescargo fmt --all -- --checkThe linked cosmic-comp PR documents the original issue and hardware testing of the downstream workaround. This Smithay change has not been tested against legacy DRM hardware.
AI assistance is disclosed in the commit message in accordance with Smithay's AI policy.
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