feature: add on-demand vrr (#586)

* feature: add on-demand vrr

* Don't require connector::Info in try_to_set_vrr

* Improve VRR help message

* Rename connector_handle => connector

* Fix tracy span name

* Move on demand vrr flag set higher

* wiki: Mention on-demand VRR

---------

Co-authored-by: Ivan Molodetskikh <yalterz@gmail.com>

10 files changed, 201 insertions, 66 deletions

diff --git a/niri-config/src/lib.rs b/niri-config/src/lib.rs
index e9c7d346..b9edf4ce 100644
--- a/niri-config/src/lib.rs
+++ b/niri-config/src/lib.rs
@@ -324,11 +324,25 @@ pub struct Output {
     #[knuffel(child, unwrap(argument, str))]
     pub mode: Option<ConfiguredMode>,
     #[knuffel(child)]
-    pub variable_refresh_rate: bool,
+    pub variable_refresh_rate: Option<Vrr>,
     #[knuffel(child, default = DEFAULT_BACKGROUND_COLOR)]
     pub background_color: Color,
 }
 
+impl Output {
+    pub fn is_vrr_always_on(&self) -> bool {
+        self.variable_refresh_rate == Some(Vrr { on_demand: false })
+    }
+
+    pub fn is_vrr_on_demand(&self) -> bool {
+        self.variable_refresh_rate == Some(Vrr { on_demand: true })
+    }
+
+    pub fn is_vrr_always_off(&self) -> bool {
+        self.variable_refresh_rate.is_none()
+    }
+}
+
 impl Default for Output {
     fn default() -> Self {
         Self {
@@ -338,7 +352,7 @@ impl Default for Output {
             transform: Transform::Normal,
             position: None,
             mode: None,
-            variable_refresh_rate: false,
+            variable_refresh_rate: None,
             background_color: DEFAULT_BACKGROUND_COLOR,
         }
     }
@@ -352,6 +366,12 @@ pub struct Position {
     pub y: i32,
 }
 
+#[derive(knuffel::Decode, Debug, Clone, PartialEq, Default)]
+pub struct Vrr {
+    #[knuffel(property, default = false)]
+    pub on_demand: bool,
+}
+
 // MIN and MAX generics are only used during parsing to check the value.
 #[derive(Debug, Default, Clone, Copy, PartialEq)]
 pub struct FloatOrInt<const MIN: i32, const MAX: i32>(pub f64);
@@ -896,6 +916,8 @@ pub struct WindowRule {
     pub clip_to_geometry: Option<bool>,
     #[knuffel(child, unwrap(argument))]
     pub block_out_from: Option<BlockOutFrom>,
+    #[knuffel(child, unwrap(argument))]
+    pub variable_refresh_rate: Option<bool>,
 }
 
 // Remember to update the PartialEq impl when adding fields!
@@ -2705,7 +2727,7 @@ mod tests {
                 transform "flipped-90"
                 position x=10 y=20
                 mode "1920x1080@144"
-                variable-refresh-rate
+                variable-refresh-rate on-demand=true
                 background-color "rgba(25, 25, 102, 1.0)"
             }
 
@@ -2889,7 +2911,7 @@ mod tests {
                         height: 1080,
                         refresh: Some(144.),
                     }),
-                    variable_refresh_rate: true,
+                    variable_refresh_rate: Some(Vrr { on_demand: true }),
                     background_color: Color::from_rgba8_unpremul(25, 25, 102, 255),
                 }]),
                 layout: Layout {
diff --git a/niri-ipc/src/lib.rs b/niri-ipc/src/lib.rs
index 7317436c..713db8af 100644
--- a/niri-ipc/src/lib.rs
+++ b/niri-ipc/src/lib.rs
@@ -352,18 +352,11 @@ pub enum OutputAction {
         #[cfg_attr(feature = "clap", command(subcommand))]
         position: PositionToSet,
     },
-    /// Toggle variable refresh rate.
+    /// Set the variable refresh rate mode.
     Vrr {
-        /// Whether to enable variable refresh rate.
-        #[cfg_attr(
-            feature = "clap",
-            arg(
-                value_name = "ON|OFF",
-                action = clap::ArgAction::Set,
-                value_parser = clap::builder::BoolishValueParser::new(),
-            ),
-        )]
-        enable: bool,
+        /// Variable refresh rate mode to set.
+        #[cfg_attr(feature = "clap", command(flatten))]
+        vrr: VrrToSet,
     },
 }
 
@@ -425,6 +418,27 @@ pub struct ConfiguredPosition {
     pub y: i32,
 }
 
+/// Output VRR to set.
+#[derive(Serialize, Deserialize, Debug, Clone, Copy, PartialEq)]
+#[cfg_attr(feature = "clap", derive(clap::Args))]
+#[cfg_attr(feature = "json-schema", derive(schemars::JsonSchema))]
+pub struct VrrToSet {
+    /// Whether to enable variable refresh rate.
+    #[cfg_attr(
+        feature = "clap",
+        arg(
+            value_name = "ON|OFF",
+            action = clap::ArgAction::Set,
+            value_parser = clap::builder::BoolishValueParser::new(),
+            hide_possible_values = true,
+        ),
+    )]
+    pub vrr: bool,
+    /// Only enable when the output shows a window matching the variable-refresh-rate window rule.
+    #[cfg_attr(feature = "clap", arg(long))]
+    pub on_demand: bool,
+}
+
 /// Connected output.
 #[derive(Debug, Serialize, Deserialize, Clone)]
 #[cfg_attr(feature = "json-schema", derive(schemars::JsonSchema))]
diff --git a/src/backend/mod.rs b/src/backend/mod.rs
index c5662184..850f47ef 100644
--- a/src/backend/mod.rs
+++ b/src/backend/mod.rs
@@ -153,6 +153,13 @@ impl Backend {
         }
     }
 
+    pub fn set_output_on_demand_vrr(&mut self, niri: &mut Niri, output: &Output, enable_vrr: bool) {
+        match self {
+            Backend::Tty(tty) => tty.set_output_on_demand_vrr(niri, output, enable_vrr),
+            Backend::Winit(_) => (),
+        }
+    }
+
     pub fn on_output_config_changed(&mut self, niri: &mut Niri) {
         match self {
             Backend::Tty(tty) => tty.on_output_config_changed(niri),
diff --git a/src/backend/tty.rs b/src/backend/tty.rs
index 10becafe..1d891d91 100644
--- a/src/backend/tty.rs
+++ b/src/backend/tty.rs
@@ -180,6 +180,7 @@ struct TtyOutputState {
 struct Surface {
     name: String,
     compositor: GbmDrmCompositor,
+    connector: connector::Handle,
     dmabuf_feedback: Option<SurfaceDmabufFeedback>,
     gamma_props: Option<GammaProps>,
     /// Gamma change to apply upon session resume.
@@ -426,18 +427,6 @@ impl Tty {
                         }
 
                         // Restore VRR.
-                        let Some(connector) =
-                            surface.compositor.pending_connectors().into_iter().next()
-                        else {
-                            error!("surface pending connectors is empty");
-                            continue;
-                        };
-                        let Some(connector) = device.drm_scanner.connectors().get(&connector)
-                        else {
-                            error!("missing enabled connector in drm_scanner");
-                            continue;
-                        };
-
                         let output = niri
                             .global_space
                             .outputs()
@@ -457,7 +446,7 @@ impl Tty {
 
                         try_to_change_vrr(
                             &device.drm,
-                            connector,
+                            surface.connector,
                             *crtc,
                             surface,
                             output_state,
@@ -832,15 +821,13 @@ impl Tty {
         let mut vrr_enabled = false;
         if let Some(capable) = is_vrr_capable(&device.drm, connector.handle()) {
             if capable {
-                let word = if config.variable_refresh_rate {
-                    "enabling"
-                } else {
-                    "disabling"
-                };
+                // Even if on-demand, we still disable it until later checks.
+                let vrr = config.is_vrr_always_on();
+                let word = if vrr { "enabling" } else { "disabling" };
 
-                match set_vrr_enabled(&device.drm, crtc, config.variable_refresh_rate) {
+                match set_vrr_enabled(&device.drm, crtc, vrr) {
                     Ok(enabled) => {
-                        if enabled != config.variable_refresh_rate {
+                        if enabled != vrr {
                             warn!("failed {} VRR", word);
                         }
 
@@ -851,13 +838,13 @@ impl Tty {
                     }
                 }
             } else {
-                if config.variable_refresh_rate {
+                if !config.is_vrr_always_off() {
                     warn!("cannot enable VRR because connector is not vrr_capable");
                 }
 
                 // Try to disable it anyway to work around a bug where resetting DRM state causes
                 // vrr_capable to be reset to 0, potentially leaving VRR_ENABLED at 1.
-                let res = set_vrr_enabled(&device.drm, crtc, config.variable_refresh_rate);
+                let res = set_vrr_enabled(&device.drm, crtc, false);
                 if matches!(res, Ok(true)) {
                     warn!("error disabling VRR");
 
@@ -865,7 +852,7 @@ impl Tty {
                     vrr_enabled = true;
                 }
             }
-        } else if config.variable_refresh_rate {
+        } else if !config.is_vrr_always_off() {
             warn!("cannot enable VRR because connector is not vrr_capable");
         }
 
@@ -1017,6 +1004,7 @@ impl Tty {
 
         let surface = Surface {
             name: output_name.clone(),
+            connector: connector.handle(),
             compositor,
             dmabuf_feedback,
             gamma_props,
@@ -1661,6 +1649,33 @@ impl Tty {
         }
     }
 
+    pub fn set_output_on_demand_vrr(&mut self, niri: &mut Niri, output: &Output, enable_vrr: bool) {
+        let _span = tracy_client::span!("Tty::set_output_on_demand_vrr");
+
+        let output_state = niri.output_state.get_mut(output).unwrap();
+        output_state.on_demand_vrr_enabled = enable_vrr;
+        if output_state.frame_clock.vrr() == enable_vrr {
+            return;
+        }
+        for (&node, device) in self.devices.iter_mut() {
+            for (&crtc, surface) in device.surfaces.iter_mut() {
+                let tty_state: &TtyOutputState = output.user_data().get().unwrap();
+                if tty_state.node == node && tty_state.crtc == crtc {
+                    try_to_change_vrr(
+                        &device.drm,
+                        surface.connector,
+                        crtc,
+                        surface,
+                        output_state,
+                        enable_vrr,
+                    );
+                    self.refresh_ipc_outputs(niri);
+                    return;
+                }
+            }
+        }
+    }
+
     pub fn on_output_config_changed(&mut self, niri: &mut Niri) {
         let _span = tracy_client::span!("Tty::on_output_config_changed");
 
@@ -1675,9 +1690,7 @@ impl Tty {
         let mut to_connect = vec![];
 
         for (&node, device) in &mut self.devices {
-            for surface in device.surfaces.values_mut() {
-                let crtc = surface.compositor.crtc();
-
+            for (&crtc, surface) in device.surfaces.iter_mut() {
                 let config = self
                     .config
                     .borrow()
@@ -1691,12 +1704,8 @@ impl Tty {
                 }
 
                 // Check if we need to change the mode.
-                let Some(connector) = surface.compositor.pending_connectors().into_iter().next()
+                let Some(connector) = device.drm_scanner.connectors().get(&surface.connector)
                 else {
-                    error!("surface pending connectors is empty");
-                    continue;
-                };
-                let Some(connector) = device.drm_scanner.connectors().get(&connector) else {
                     error!("missing enabled connector in drm_scanner");
                     continue;
                 };
@@ -1707,8 +1716,9 @@ impl Tty {
                 };
 
                 let change_mode = surface.compositor.pending_mode() != mode;
-                let change_vrr = surface.vrr_enabled != config.variable_refresh_rate;
-                if !change_mode && !change_vrr {
+                let change_always_vrr = surface.vrr_enabled != config.is_vrr_always_on();
+                let is_on_demand_vrr = config.is_vrr_on_demand();
+                if !change_mode && !change_always_vrr && !is_on_demand_vrr {
                     continue;
                 }
 
@@ -1729,14 +1739,16 @@ impl Tty {
                     continue;
                 };
 
-                if change_vrr {
+                if (is_on_demand_vrr && surface.vrr_enabled != output_state.on_demand_vrr_enabled)
+                    || (!is_on_demand_vrr && change_always_vrr)
+                {
                     try_to_change_vrr(
                         &device.drm,
-                        connector,
+                        connector.handle(),
                         crtc,
                         surface,
                         output_state,
-                        config.variable_refresh_rate,
+                        !surface.vrr_enabled,
                     );
                 }
 
@@ -2388,7 +2400,7 @@ pub fn set_gamma_for_crtc(
 
 fn try_to_change_vrr(
     device: &DrmDevice,
-    connector: &connector::Info,
+    connector: connector::Handle,
     crtc: crtc::Handle,
     surface: &mut Surface,
     output_state: &mut crate::niri::OutputState,
@@ -2396,7 +2408,7 @@ fn try_to_change_vrr(
 ) {
     let _span = tracy_client::span!("try_to_change_vrr");
 
-    if is_vrr_capable(device, connector.handle()) == Some(true) {
+    if is_vrr_capable(device, connector) == Some(true) {
         let word = if enable_vrr { "enabling" } else { "disabling" };
 
         match set_vrr_enabled(device, crtc, enable_vrr) {
diff --git a/src/frame_clock.rs b/src/frame_clock.rs
index d60867ea..f96475c8 100644
--- a/src/frame_clock.rs
+++ b/src/frame_clock.rs
@@ -40,6 +40,10 @@ impl FrameClock {
         self.last_presentation_time = None;
     }
 
+    pub fn vrr(&self) -> bool {
+        self.vrr
+    }
+
     pub fn presented(&mut self, presentation_time: Duration) {
         if presentation_time.is_zero() {
             // Not interested in these.
diff --git a/src/niri.rs b/src/niri.rs
index 9aec5ed1..ac07f113 100644
--- a/src/niri.rs
+++ b/src/niri.rs
@@ -299,6 +299,7 @@ pub struct OutputState {
     pub global: GlobalId,
     pub frame_clock: FrameClock,
     pub redraw_state: RedrawState,
+    pub on_demand_vrr_enabled: bool,
     // After the last redraw, some ongoing animations still remain.
     pub unfinished_animations_remain: bool,
     /// Last sequence received in a vblank event.
@@ -1202,8 +1203,14 @@ impl State {
                         }
                     }
                 }
-                niri_ipc::OutputAction::Vrr { enable } => {
-                    config.variable_refresh_rate = enable;
+                niri_ipc::OutputAction::Vrr { vrr } => {
+                    config.variable_refresh_rate = if vrr.vrr {
+                        Some(niri_config::Vrr {
+                            on_demand: vrr.on_demand,
+                        })
+                    } else {
+                        None
+                    }
                 }
             }
         }
@@ -2005,6 +2012,7 @@ impl Niri {
         let state = OutputState {
             global,
             redraw_state: RedrawState::Idle,
+            on_demand_vrr_enabled: false,
             unfinished_animations_remain: false,
             frame_clock: FrameClock::new(refresh_interval, vrr),
             last_drm_sequence: None,
@@ -3089,6 +3097,8 @@ impl Niri {
             lock_state => self.lock_state = lock_state,
         }
 
+        self.refresh_on_demand_vrr(backend, output);
+
         // Send the frame callbacks.
         //
         // FIXME: The logic here could be a bit smarter. Currently, during an animation, the
@@ -3118,6 +3128,39 @@ impl Niri {
         });
     }
 
+    pub fn refresh_on_demand_vrr(&mut self, backend: &mut Backend, output: &Output) {
+        let _span = tracy_client::span!("Niri::refresh_on_demand_vrr");
+        let Some(on_demand) = self
+            .config
+            .borrow()
+            .outputs
+            .find(&output.name())
+            .map(|output| output.is_vrr_on_demand())
+        else {
+            warn!("error getting output config for {}", output.name());
+            return;
+        };
+        if !on_demand {
+            return;
+        }
+
+        let current = self.layout.windows_for_output(output).any(|mapped| {
+            mapped.rules().variable_refresh_rate == Some(true) && {
+                let mut visible = false;
+                mapped.window.with_surfaces(|surface, states| {
+                    if !visible
+                        && surface_primary_scanout_output(surface, states).as_ref() == Some(output)
+                    {
+                        visible = true;
+                    }
+                });
+                visible
+            }
+        });
+
+        backend.set_output_on_demand_vrr(self, output, current);
+    }
+
     pub fn update_primary_scanout_output(
         &self,
         output: &Output,
@@ -3181,13 +3224,9 @@ impl Niri {
             let offscreen_id = offscreen_id.as_ref();
 
             win.with_surfaces(|surface, states| {
-                states
-                    .data_map
-                    .insert_if_missing_threadsafe(Mutex::<PrimaryScanoutOutput>::default);
                 let surface_primary_scanout_output = states
                     .data_map
-                    .get::<Mutex<PrimaryScanoutOutput>>()
-                    .unwrap();
+                    .get_or_insert_threadsafe(Mutex::<PrimaryScanoutOutput>::default);
                 surface_primary_scanout_output
                     .lock()
                     .unwrap()
diff --git a/src/protocols/output_management.rs b/src/protocols/output_management.rs
index 23e419ba..3839bdb4 100644
--- a/src/protocols/output_management.rs
+++ b/src/protocols/output_management.rs
@@ -3,7 +3,7 @@ use std::collections::HashMap;
 use std::iter::zip;
 use std::mem;
 
-use niri_config::FloatOrInt;
+use niri_config::{FloatOrInt, Vrr};
 use niri_ipc::Transform;
 use smithay::reexports::wayland_protocols_wlr::output_management::v1::server::{
     zwlr_output_configuration_head_v1, zwlr_output_configuration_v1, zwlr_output_head_v1,
@@ -693,9 +693,9 @@ where
                 new_config.scale = Some(FloatOrInt(scale));
             }
             zwlr_output_configuration_head_v1::Request::SetAdaptiveSync { state } => {
-                let enabled = match state {
-                    WEnum::Value(AdaptiveSyncState::Enabled) => true,
-                    WEnum::Value(AdaptiveSyncState::Disabled) => false,
+                let vrr = match state {
+                    WEnum::Value(AdaptiveSyncState::Enabled) => Some(Vrr { on_demand: false }),
+                    WEnum::Value(AdaptiveSyncState::Disabled) => None,
                     _ => {
                         warn!("SetAdaptativeSync: unknown requested adaptative sync");
                         conf_head.post_error(
@@ -705,7 +705,7 @@ where
                         return;
                     }
                 };
-                new_config.variable_refresh_rate = enabled;
+                new_config.variable_refresh_rate = vrr;
             }
             _ => unreachable!(),
         }
diff --git a/src/window/mod.rs b/src/window/mod.rs
index 0e0774fd..4d06bb04 100644
--- a/src/window/mod.rs
+++ b/src/window/mod.rs
@@ -72,6 +72,9 @@ pub struct ResolvedWindowRules {
 
     /// Whether to block out this window from certain render targets.
     pub block_out_from: Option<BlockOutFrom>,
+
+    /// Whether to enable VRR on this window's primary output if it is on-demand.
+    pub variable_refresh_rate: Option<bool>,
 }
 
 impl<'a> WindowRef<'a> {
@@ -132,6 +135,7 @@ impl ResolvedWindowRules {
             geometry_corner_radius: None,
             clip_to_geometry: None,
             block_out_from: None,
+            variable_refresh_rate: None,
         }
     }
 
@@ -231,6 +235,9 @@ impl ResolvedWindowRules {
                 if let Some(x) = rule.block_out_from {
                     resolved.block_out_from = Some(x);
                 }
+                if let Some(x) = rule.variable_refresh_rate {
+                    resolved.variable_refresh_rate = Some(x);
+                }
             }
 
             resolved.open_on_output = open_on_output.map(|x| x.to_owned());
diff --git a/wiki/Configuration:-Outputs.md b/wiki/Configuration:-Outputs.md
index eef06fef..f7b3adf8 100644
--- a/wiki/Configuration:-Outputs.md
+++ b/wiki/Configuration:-Outputs.md
@@ -12,7 +12,7 @@ output "eDP-1" {
     scale 2.0
     transform "90"
     position x=1280 y=0
-    variable-refresh-rate
+    variable-refresh-rate // on-demand=true
     background-color "#003300"
 }
 
@@ -147,6 +147,15 @@ output "HDMI-A-1" {
 }
 ```
 
+<sup>Since: 0.1.9</sup> You can also set the `on-demand=true` property, which will only enable VRR when this output shows a window matching the `variable-refresh-rate` window rule.
+This is helpful to avoid various issues with VRR, since it can be disabled most of the time, and only enabled for specific windows, like games or video players.
+
+```kdl
+output "HDMI-A-1" {
+    variable-refresh-rate on-demand=true
+}
+```
+
 ### `background-color`
 
 <sup>Since: 0.1.8</sup>
diff --git a/wiki/Configuration:-Window-Rules.md b/wiki/Configuration:-Window-Rules.md
index 3daceb15..b13b4661 100644
--- a/wiki/Configuration:-Window-Rules.md
+++ b/wiki/Configuration:-Window-Rules.md
@@ -47,6 +47,7 @@ window-rule {
     opacity 0.5
     block-out-from "screencast"
     // block-out-from "screen-capture"
+    variable-refresh-rate true
 
     focus-ring {
         // off
@@ -391,6 +392,26 @@ window-rule {
 }
 ```
 
+#### `variable-refresh-rate`
+
+<sup>Since: 0.1.9</sup>
+
+If set to true, whenever this window displays on an output with on-demand VRR, it will enable VRR on that output.
+
+```kdl
+// Configure some output with on-demand VRR.
+output "HDMI-A-1" {
+    variable-refresh-rate on-demand=true
+}
+
+// Enable on-demand VRR when mpv displays on the output.
+window-rule {
+    match app-id="^mpv$"
+
+    variable-refresh-rate true
+}
+```
+
 #### `draw-border-with-background`
 
 Override whether the border and the focus ring draw with a background.