eglfs: Add vsync support when using NVIDIA eglstreams

Similar to the kms backend a flip event handler can be retrieved using
the drmEvent API to implement vsync.
For this to work the acquire calls need to be done manuallly and the
automatic acquiring needs to be disabled.

Change-Id: I670d288ef68eb49846108db2a31993c6167d9313
Reviewed-by: Laszlo Agocs <laszlo.agocs@qt.io>

2 files changed, 52 insertions, 0 deletions

diff --git a/src/plugins/platforms/eglfs/deviceintegration/eglfs_kms_egldevice/qeglfskmsegldeviceintegration.cpp b/src/plugins/platforms/eglfs/deviceintegration/eglfs_kms_egldevice/qeglfskmsegldeviceintegration.cpp
index ab39af6b80..9f4c9f5703 100644
--- a/src/plugins/platforms/eglfs/deviceintegration/eglfs_kms_egldevice/qeglfskmsegldeviceintegration.cpp
+++ b/src/plugins/platforms/eglfs/deviceintegration/eglfs_kms_egldevice/qeglfskmsegldeviceintegration.cpp
@@ -114,14 +114,18 @@ public:
         : QEglFSWindow(w)
         , m_integration(integration)
         , m_egl_stream(EGL_NO_STREAM_KHR)
+        , m_framePending(false)
     { }
 
     void invalidateSurface() override;
     void resetSurface() override;
+    void flip();
+    static void pageFlipHandler(int fd, unsigned int sequence, unsigned int tv_sec, unsigned int tv_usec, void *user_data);
 
     const QEglFSKmsEglDeviceIntegration *m_integration;
     EGLStreamKHR m_egl_stream;
     EGLint m_latency;
+    bool m_framePending;
 };
 
 void QEglFSKmsEglDeviceWindow::invalidateSurface()
@@ -142,6 +146,9 @@ void QEglFSKmsEglDeviceWindow::resetSurface()
         streamAttribs[streamAttribCount++] = EGL_STREAM_FIFO_LENGTH_KHR;
         streamAttribs[streamAttribCount++] = fifoLength;
     }
+
+    streamAttribs[streamAttribCount++] = EGL_CONSUMER_AUTO_ACQUIRE_EXT;
+    streamAttribs[streamAttribCount++] = EGL_FALSE;
     streamAttribs[streamAttribCount++] = EGL_NONE;
 
     m_egl_stream = m_integration->m_funcs->create_stream(display, streamAttribs);
@@ -239,6 +246,49 @@ void QEglFSKmsEglDeviceWindow::resetSurface()
     qCDebug(qLcEglfsKmsDebug, "Created stream producer surface %p", m_surface);
 }
 
+void QEglFSKmsEglDeviceWindow::flip()
+{
+    EGLDisplay display = screen()->display();
+
+    EGLAttrib acquire_attribs[3] = { EGL_NONE };
+
+    acquire_attribs[0] = EGL_DRM_FLIP_EVENT_DATA_NV;
+    acquire_attribs[1] = (EGLAttrib)this;
+    acquire_attribs[2] = EGL_NONE;
+
+    if (m_egl_stream != EGL_NO_STREAM_KHR)
+        if (!m_integration->m_funcs->acquire_stream_attrib_nv(display, m_egl_stream, acquire_attribs))
+            qWarning("eglStreamConsumerAcquireAttribNV failed: eglError: %x", eglGetError());
+
+    m_framePending = true;
+
+    while (m_framePending) {
+        drmEventContext drmEvent;
+        memset(&drmEvent, 0, sizeof(drmEvent));
+        drmEvent.version = 3;
+        drmEvent.vblank_handler = nullptr;
+        drmEvent.page_flip_handler = pageFlipHandler;
+        drmHandleEvent(m_integration->m_device->fd(), &drmEvent);
+    }
+}
+
+void QEglFSKmsEglDeviceWindow::pageFlipHandler(int fd, unsigned int sequence, unsigned int tv_sec, unsigned int tv_usec, void *user_data)
+{
+    Q_UNUSED(fd);
+    Q_UNUSED(sequence);
+    Q_UNUSED(tv_sec);
+    Q_UNUSED(tv_usec);
+
+    QEglFSKmsEglDeviceWindow *window = static_cast<QEglFSKmsEglDeviceWindow*>(user_data);
+    window->m_framePending = false;
+}
+
+void QEglFSKmsEglDeviceIntegration::presentBuffer(QPlatformSurface *surface)
+{
+    QEglFSKmsEglDeviceWindow *eglWindow = static_cast<QEglFSKmsEglDeviceWindow*>(surface);
+    eglWindow->flip();
+}
+
 QEglFSWindow *QEglFSKmsEglDeviceIntegration::createWindow(QWindow *window) const
 {
     QEglFSKmsEglDeviceWindow *eglWindow = new QEglFSKmsEglDeviceWindow(window, this);
diff --git a/src/plugins/platforms/eglfs/deviceintegration/eglfs_kms_egldevice/qeglfskmsegldeviceintegration.h b/src/plugins/platforms/eglfs/deviceintegration/eglfs_kms_egldevice/qeglfskmsegldeviceintegration.h
index 5819d82ebf..0c64d83b12 100644
--- a/src/plugins/platforms/eglfs/deviceintegration/eglfs_kms_egldevice/qeglfskmsegldeviceintegration.h
+++ b/src/plugins/platforms/eglfs/deviceintegration/eglfs_kms_egldevice/qeglfskmsegldeviceintegration.h
@@ -62,6 +62,8 @@ public:
     bool supportsPBuffers() const override;
     QEglFSWindow *createWindow(QWindow *window) const override;
 
+    void presentBuffer(QPlatformSurface *surface);
+
     EGLDeviceEXT eglDevice() const { return m_egl_device; }
 
 protected: