drm: allow commit/page_flip calls to *not* trigger an event

src/backend/drm/surface/atomic.rs

@@ -350,7 +350,7 @@ impl<A: AsRawFd + 'static> AtomicDrmSurface<A> {
         *self.pending.read().unwrap() != *self.state.read().unwrap()
     }
 
-    pub fn commit(&self, framebuffer: framebuffer::Handle) -> Result<(), Error> {
+    pub fn commit(&self, framebuffer: framebuffer::Handle, event: bool) -> Result<(), Error> {
         if !self.active.load(Ordering::SeqCst) {
             return Err(Error::DeviceInactive);
         }
@@ -430,14 +430,21 @@ impl<A: AsRawFd + 'static> AtomicDrmSurface<A> {
         debug!(self.logger, "Setting screen: {:?}", req);
         let result = self.fd
             .atomic_commit(
-                &[
-                    // on the atomic api we can modeset and trigger a page_flip event on the same call!
-                    AtomicCommitFlags::PageFlipEvent,
-                    AtomicCommitFlags::AllowModeset,
-                    // we also do not need to wait for completion, like with `set_crtc`.
-                    // and have tested this already, so we do not expect any errors later down the line.
-                    AtomicCommitFlags::Nonblock,
-                ],
+                if event {
+                    &[
+                        // on the atomic api we can modeset and trigger a page_flip event on the same call!
+                        AtomicCommitFlags::PageFlipEvent,
+                        AtomicCommitFlags::AllowModeset,
+                        // we also do not need to wait for completion, like with `set_crtc`.
+                        // and have tested this already, so we do not expect any errors later down the line.
+                        AtomicCommitFlags::Nonblock,
+                    ]
+                } else {
+                    &[
+                        AtomicCommitFlags::AllowModeset,
+                        AtomicCommitFlags::Nonblock,
+                    ]
+                },
                 req,
             )
             .map_err(|source| Error::Access {
@@ -453,7 +460,7 @@ impl<A: AsRawFd + 'static> AtomicDrmSurface<A> {
         result
     }
 
-    pub fn page_flip(&self, framebuffer: framebuffer::Handle) -> Result<(), Error> {
+    pub fn page_flip(&self, framebuffer: framebuffer::Handle, event: bool) -> Result<(), Error> {
         if !self.active.load(Ordering::SeqCst) {
             return Err(Error::DeviceInactive);
         }
@@ -473,7 +480,11 @@ impl<A: AsRawFd + 'static> AtomicDrmSurface<A> {
         // indicating a problem in our assumptions.
         trace!(self.logger, "Queueing page flip: {:?}", req);
         self.fd.atomic_commit(
-            &[AtomicCommitFlags::PageFlipEvent, AtomicCommitFlags::Nonblock],
+            if event {
+                &[AtomicCommitFlags::PageFlipEvent, AtomicCommitFlags::Nonblock]
+            } else {
+                &[AtomicCommitFlags::Nonblock]
+            },
             req,
         )
         .map_err(|source| Error::Access {

src/backend/drm/surface/legacy.rs

@@ -202,7 +202,7 @@ impl<A: AsRawFd + 'static> LegacyDrmSurface<A> {
         *self.pending.read().unwrap() != *self.state.read().unwrap()
     }
 
-    pub fn commit(&self, framebuffer: framebuffer::Handle) -> Result<(), Error> {
+    pub fn commit(&self, framebuffer: framebuffer::Handle, event: bool) -> Result<(), Error> {
         if !self.active.load(Ordering::SeqCst) {
             return Err(Error::DeviceInactive);
         }
@@ -272,26 +272,30 @@ impl<A: AsRawFd + 'static> LegacyDrmSurface<A> {
 
         *current = pending.clone();
 
-        // set crtc does not trigger page_flip events, so we immediately queue a flip
-        // with the same framebuffer.
-        // this will result in wasting a frame, because this flip will need to wait
-        // for `set_crtc`, but is necessary to drive the event loop and thus provide
-        // a more consistent api.
-        ControlDevice::page_flip(
-            &*self.fd,
-            self.crtc,
-            framebuffer,
-            &[PageFlipFlags::PageFlipEvent],
-            None,
-        )
-        .map_err(|source| Error::Access {
-            errmsg: "Failed to queue page flip",
-            dev: self.fd.dev_path(),
-            source,
-        })
+        if event {
+            // set crtc does not trigger page_flip events, so we immediately queue a flip
+            // with the same framebuffer.
+            // this will result in wasting a frame, because this flip will need to wait
+            // for `set_crtc`, but is necessary to drive the event loop and thus provide
+            // a more consistent api.
+            ControlDevice::page_flip(
+                &*self.fd,
+                self.crtc,
+                framebuffer,
+                &[PageFlipFlags::PageFlipEvent],
+                None,
+            )
+            .map_err(|source| Error::Access {
+                errmsg: "Failed to queue page flip",
+                dev: self.fd.dev_path(),
+                source,
+            })?;
+        }
+
+        Ok(())
     }
 
-    pub fn page_flip(&self, framebuffer: framebuffer::Handle) -> Result<(), Error> {
+    pub fn page_flip(&self, framebuffer: framebuffer::Handle, event: bool) -> Result<(), Error> {
         trace!(self.logger, "Queueing Page flip");
 
         if !self.active.load(Ordering::SeqCst) {
@@ -302,7 +306,7 @@ impl<A: AsRawFd + 'static> LegacyDrmSurface<A> {
             &*self.fd,
             self.crtc,
             framebuffer,
-            &[PageFlipFlags::PageFlipEvent],
+            if event { &[PageFlipFlags::PageFlipEvent] } else { &[] },
             None,
         )
         .map_err(|source| Error::Access {

src/backend/drm/surface/mod.rs

@@ -159,10 +159,10 @@ impl<A: AsRawFd + 'static> DrmSurface<A> {
     /// but will trigger a `vblank` event once done.
     /// Make sure to [set a `DeviceHandler`](Device::set_handler) and
     /// [register the belonging `Device`](device_bind) before to receive the event in time.
-    pub fn commit(&self, framebuffer: framebuffer::Handle) -> Result<(), Error> {
+    pub fn commit(&self, framebuffer: framebuffer::Handle, event: bool) -> Result<(), Error> {
         match &*self.internal {
-            DrmSurfaceInternal::Atomic(surf) => surf.commit(framebuffer),
-            DrmSurfaceInternal::Legacy(surf) => surf.commit(framebuffer),
+            DrmSurfaceInternal::Atomic(surf) => surf.commit(framebuffer, event),
+            DrmSurfaceInternal::Legacy(surf) => surf.commit(framebuffer, event),
         }
     }
 
@@ -174,10 +174,10 @@ impl<A: AsRawFd + 'static> DrmSurface<A> {
     /// This operation is not blocking and will produce a `vblank` event once swapping is done.
     /// Make sure to [set a `DeviceHandler`](Device::set_handler) and
     /// [register the belonging `Device`](device_bind) before to receive the event in time.
-    pub fn page_flip(&self, framebuffer: framebuffer::Handle) -> Result<(), Error> {
+    pub fn page_flip(&self, framebuffer: framebuffer::Handle, event: bool) -> Result<(), Error> {
         match &*self.internal {
-            DrmSurfaceInternal::Atomic(surf) => surf.page_flip(framebuffer),
-            DrmSurfaceInternal::Legacy(surf) => surf.page_flip(framebuffer)
+            DrmSurfaceInternal::Atomic(surf) => surf.page_flip(framebuffer, event),
+            DrmSurfaceInternal::Legacy(surf) => surf.page_flip(framebuffer, event),
         }
     }