metal: disable implicit sync in KMS

src/backends/metal.rs

@@ -16,7 +16,7 @@ use {
         },
         dbus::{DbusError, SignalHandler},
         drm_feedback::DrmFeedback,
-        gfx_api::GfxError,
+        gfx_api::{GfxError, SyncFile},
         ifs::{
             wl_output::OutputId,
             wl_seat::tablet::{
@@ -150,6 +150,7 @@ pub struct MetalBackend {
     pause_handler: Cell<Option<SignalHandler>>,
     resume_handler: Cell<Option<SignalHandler>>,
     ctx: CloneCell<Option<Rc<MetalRenderContext>>>,
+    signaled_sync_file: CloneCell<Option<SyncFile>>,
     default_feedback: CloneCell<Option<Rc<DrmFeedback>>>,
     persistent_display_data: CopyHashMap<Rc<OutputId>, Rc<PersistentDisplayData>>,
 }
@@ -324,6 +325,7 @@ pub async fn create(state: &Rc<State>) -> Result<Rc<MetalBackend>, MetalError> {
         pause_handler: Default::default(),
         resume_handler: Default::default(),
         ctx: Default::default(),
+        signaled_sync_file: Default::default(),
         default_feedback: Default::default(),
         persistent_display_data: Default::default(),
     });

src/backends/metal/present.rs

@@ -292,7 +292,9 @@ impl MetalConnector {
                 change!(c, plane.crtc_w, crtc_w);
                 change!(c, plane.crtc_h, crtc_h);
                 if !try_async_flip && !self.dev.is_nvidia {
-                    c.change(plane.in_fence_fd, -1i32 as u64);
+                    if let Some(sf) = self.backend.signaled_sync_file.get() {
+                        c.change(plane.in_fence_fd, sf.0.raw() as u64);
+                    }
                 }
             });
         } else {
@@ -329,7 +331,9 @@ impl MetalConnector {
                         c.change(plane.src_w.id, (*width as u64) << 16);
                         c.change(plane.src_h.id, (*height as u64) << 16);
                         if !self.dev.is_nvidia {
-                            c.change(plane.in_fence_fd, -1i32 as u64);
+                            if let Some(sf) = self.backend.signaled_sync_file.get() {
+                                c.change(plane.in_fence_fd, sf.0.raw() as u64);
+                            }
                         }
                     });
                 }
@@ -512,8 +516,8 @@ impl MetalConnector {
             }
             ct
         };
-        if let AcquireSync::None = ct.acquire_sync {
+        if let AcquireSync::None | AcquireSync::Implicit = ct.acquire_sync {
-            // Cannot perform scanout without sync.
+            // Cannot perform scanout without explicit sync.
             return None;
         }
         if ct.source.buffer_transform != ct.target.output_transform {

src/backends/metal/video.rs

@@ -2029,6 +2029,18 @@ impl MetalBackend {
             }
         }
         let ctx = dev.ctx.get();
+        if self.signaled_sync_file.is_none() {
+            if let Some(sync) = ctx.gfx.sync_obj_ctx() {
+                match sync.create_signaled_sync_file() {
+                    Ok(sf) => {
+                        self.signaled_sync_file.set(Some(sf));
+                    }
+                    Err(e) => {
+                        log::warn!("Could not create signaled sync file: {}", ErrorFmt(e));
+                    }
+                }
+            }
+        }
         self.state.set_render_ctx(Some(ctx.gfx.clone()));
         let fb = match DrmFeedback::new(&self.state.drm_feedback_ids, &*ctx.gfx) {
             Ok(fb) => Some(Rc::new(fb)),

src/video/drm/sync_obj.rs

@@ -13,7 +13,8 @@ use {
             sys::{
                 sync_ioc_merge, sync_obj_create, sync_obj_destroy, sync_obj_eventfd,
                 sync_obj_fd_to_handle, sync_obj_handle_to_fd, sync_obj_signal, sync_obj_transfer,
-                DRM_SYNCOBJ_FD_TO_HANDLE_FLAGS_IMPORT_SYNC_FILE,
+                DRM_SYNCOBJ_CREATE_SIGNALED, DRM_SYNCOBJ_FD_TO_HANDLE_FLAGS_IMPORT_SYNC_FILE,
+                DRM_SYNCOBJ_HANDLE_TO_FD_FLAGS_EXPORT_SYNC_FILE,
                 DRM_SYNCOBJ_WAIT_FLAGS_WAIT_AVAILABLE,
             },
             DrmError,
@@ -125,6 +126,21 @@ impl SyncObjCtx {
         Ok(sync_obj)
     }
 
+    pub fn create_signaled_sync_file(&self) -> Result<SyncFile, DrmError> {
+        let handle = sync_obj_create(self.inner.drm.raw(), DRM_SYNCOBJ_CREATE_SIGNALED)
+            .map_err(DrmError::CreateSyncObj)?;
+        let handle = SyncObjHandle(handle);
+        let fd = sync_obj_handle_to_fd(
+            self.inner.drm.raw(),
+            handle.0,
+            DRM_SYNCOBJ_HANDLE_TO_FD_FLAGS_EXPORT_SYNC_FILE,
+        );
+        destroy(&self.inner.drm, handle);
+        fd.map_err(DrmError::ExportSyncObj)
+            .map(Rc::new)
+            .map(SyncFile)
+    }
+
     pub fn wait_for_point(
         &self,
         eventfd: &OwnedFd,

src/video/drm/sys.rs

@@ -1177,7 +1177,7 @@ pub struct drm_format_modifier {
 
 unsafe impl Pod for drm_format_modifier {}
 
-// pub const DRM_SYNCOBJ_CREATE_SIGNALED: u32 = 1 << 0;
+pub const DRM_SYNCOBJ_CREATE_SIGNALED: u32 = 1 << 0;
 
 #[repr(C)]
 struct drm_syncobj_create {
@@ -1212,7 +1212,7 @@ pub fn sync_obj_destroy(drm: c::c_int, handle: u32) -> Result<(), OsError> {
 }
 
 pub const DRM_SYNCOBJ_FD_TO_HANDLE_FLAGS_IMPORT_SYNC_FILE: u32 = 1 << 0;
-// pub const DRM_SYNCOBJ_HANDLE_TO_FD_FLAGS_EXPORT_SYNC_FILE: u32 = 1 << 0;
+pub const DRM_SYNCOBJ_HANDLE_TO_FD_FLAGS_EXPORT_SYNC_FILE: u32 = 1 << 0;
 
 #[repr(C)]
 struct drm_syncobj_handle {