config: allow disabling explicit-sync

jay-config/src/_private/client.rs

@@ -810,6 +810,10 @@ impl Client {
         self.send(&ClientMessage::SetIdle { timeout })
     }
 
+    pub fn set_explicit_sync_enabled(&self, enabled: bool) {
+        self.send(&ClientMessage::SetExplicitSyncEnabled { enabled })
+    }
+
     pub fn set_seat(&self, device: InputDevice, seat: Seat) {
         self.send(&ClientMessage::SetSeat { device, seat })
     }

jay-config/src/_private/ipc.rs

@@ -428,6 +428,9 @@ pub enum ClientMessage<'a> {
         workspace: WorkspaceSource,
         connector: Connector,
     },
+    SetExplicitSyncEnabled {
+        enabled: bool,
+    },
 }
 
 #[derive(Serialize, Deserialize, Debug)]

jay-config/src/lib.rs

@@ -222,3 +222,12 @@ pub fn workspaces() -> Vec<Workspace> {
 pub fn set_idle(timeout: Option<Duration>) {
     get!().set_idle(timeout.unwrap_or_default())
 }
+
+/// Enables or disables explicit sync.
+///
+/// Calling this after the compositor has started has no effect.
+///
+/// The default is `true`.
+pub fn set_explicit_sync_enabled(enabled: bool) {
+    get!().set_explicit_sync_enabled(enabled);
+}

src/compositor.rs

@@ -224,6 +224,7 @@ fn start_compositor2(
         create_default_seat: Cell::new(true),
         subsurface_ids: Default::default(),
         wait_for_sync_obj: Rc::new(WaitForSyncObj::new(&ring, &engine)),
+        explicit_sync_enabled: Cell::new(true),
     });
     state.tracker.register(ClientId::from_raw(0));
     create_dummy_output(&state);

src/config/handler.rs

@@ -800,6 +800,10 @@ impl ConfigProxyHandler {
         self.state.idle.set_timeout(timeout);
     }
 
+    fn handle_set_explicit_sync_enabled(&self, enabled: bool) {
+        self.state.explicit_sync_enabled.set(enabled);
+    }
+
     fn handle_connector_connected(&self, connector: Connector) -> Result<(), CphError> {
         let connector = self.get_connector(connector)?;
         self.respond(Response::ConnectorConnected {
@@ -1725,6 +1729,9 @@ impl ConfigProxyHandler {
             } => self
                 .handle_move_to_output(workspace, connector)
                 .wrn("move_to_output")?,
+            ClientMessage::SetExplicitSyncEnabled { enabled } => {
+                self.handle_set_explicit_sync_enabled(enabled)
+            }
         }
         Ok(())
     }

src/state.rs

@@ -172,6 +172,7 @@ pub struct State {
     pub create_default_seat: Cell<bool>,
     pub subsurface_ids: SubsurfaceIds,
     pub wait_for_sync_obj: Rc<WaitForSyncObj>,
+    pub explicit_sync_enabled: Cell<bool>,
 }
 
 // impl Drop for State {
@@ -450,7 +451,7 @@ impl State {
             if !self.render_ctx_ever_initialized.replace(true) {
                 self.add_global(&Rc::new(WlDrmGlobal::new(self.globals.name())));
                 self.add_global(&Rc::new(ZwpLinuxDmabufV1Global::new(self.globals.name())));
-                if ctx.sync_obj_ctx().supports_async_wait() {
+                if ctx.sync_obj_ctx().supports_async_wait() && self.explicit_sync_enabled.get() {
                     self.add_global(&Rc::new(WpLinuxDrmSyncobjManagerV1Global::new(
                         self.globals.name(),
                     )));

toml-config/src/config.rs

@@ -289,6 +289,7 @@ pub struct Config {
     pub render_device: Option<DrmDeviceMatch>,
     pub inputs: Vec<Input>,
     pub idle: Option<Duration>,
+    pub explicit_sync_enabled: Option<bool>,
 }
 
 #[derive(Debug, Error)]

toml-config/src/config/parsers/config.rs

@@ -95,6 +95,7 @@ impl Parser for ConfigParser<'_> {
                 _,
                 idle_val,
             ),
+            (explicit_sync,),
         ) = ext.extract((
             (
                 opt(val("keymap")),
@@ -120,6 +121,7 @@ impl Parser for ConfigParser<'_> {
                 opt(val("$schema")),
                 opt(val("idle")),
             ),
+            (recover(opt(bol("explicit-sync"))),),
         ))?;
         let mut keymap = None;
         if let Some(value) = keymap_val {
@@ -271,6 +273,7 @@ impl Parser for ConfigParser<'_> {
             gfx_api,
             drm_devices,
             direct_scanout_enabled: direct_scanout.despan(),
+            explicit_sync_enabled: explicit_sync.despan(),
             render_device,
             inputs,
             idle,

toml-config/src/lib.rs

@@ -19,7 +19,8 @@ use {
         is_reload,
         keyboard::{Keymap, ModifiedKeySym},
         logging::set_log_level,
-        on_devices_enumerated, on_idle, quit, reload, set_default_workspace_capture, set_idle,
+        on_devices_enumerated, on_idle, quit, reload, set_default_workspace_capture,
+        set_explicit_sync_enabled, set_idle,
         status::{set_i3bar_separator, set_status, set_status_command, unset_status_command},
         switch_to_vt,
         theme::{reset_colors, reset_font, reset_sizes, set_font},
@@ -789,6 +790,9 @@ fn load_config(initial_load: bool, persistent: &Rc<PersistentState>) {
     if let Some(dse) = config.direct_scanout_enabled {
         set_direct_scanout_enabled(dse);
     }
+    if let Some(ese) = config.explicit_sync_enabled {
+        set_explicit_sync_enabled(ese);
+    }
     on_new_drm_device({
         let state = state.clone();
         move |d| {

toml-spec/spec/spec.generated.json

@@ -498,6 +498,10 @@
           "type": "boolean",
           "description": "Configured whether the compositor attempts direct scanout.\n"
         },
+        "explicit-sync": {
+          "type": "boolean",
+          "description": "Configures whether the compositor supports explicit sync.\n\nThis cannot be changed after the compositor has started.\n\nThe default is `true`.\n"
+        },
         "render-device": {
           "description": "Selects the device to use for rendering in a system with multiple GPUs.\n\nThe first device that matches will be used.\n\n- Example:\n\n  ```toml\n  render-device.name = \"dedicated\"\n\n  [[drm-devices]]\n  name = \"dedicated\"\n  match = { pci-vendor = 0x1002, pci-model = 0x73ff }\n  ```\n",
           "$ref": "#/$defs/DrmDeviceMatch"

toml-spec/spec/spec.generated.md

@@ -887,6 +887,16 @@ The table has the following fields:
 
   The value of this field should be a boolean.
 
+- `explicit-sync` (optional):
+
+  Configures whether the compositor supports explicit sync.
+  
+  This cannot be changed after the compositor has started.
+  
+  The default is `true`.
+
+  The value of this field should be a boolean.
+
 - `render-device` (optional):
 
   Selects the device to use for rendering in a system with multiple GPUs.

toml-spec/spec/spec.yaml

@@ -1875,6 +1875,15 @@ Config:
       required: false
       description: |
         Configured whether the compositor attempts direct scanout.
+    explicit-sync:
+      kind: boolean
+      required: false
+      description: |
+        Configures whether the compositor supports explicit sync.
+        
+        This cannot be changed after the compositor has started.
+        
+        The default is `true`.
     render-device:
       ref: DrmDeviceMatch
       required: false