Refactor DRM presentation

Presentation doesn't have to go through DrmBackend and by moving
DrmGpu::deleteBufferAfterPageflip into DrmBuffer some code can be
simplified

src/plugins/platforms/drm/drm_backend.cpp

@@ -516,23 +516,6 @@ DrmOutput *DrmBackend::findOutput(quint32 connector)
     return nullptr;
 }
 
-bool DrmBackend::present(DrmBuffer *buffer, DrmOutput *output)
-{
-    if (!buffer || buffer->bufferId() == 0) {
-        if (output->gpu()->deleteBufferAfterPageFlip()) {
-            delete buffer;
-        }
-        return false;
-    }
-
-    if (output->present(buffer)) {
-        return true;
-    } else if (output->gpu()->deleteBufferAfterPageFlip()) {
-        delete buffer;
-    }
-    return false;
-}
-
 void DrmBackend::initCursor()
 {
 
@@ -640,7 +623,6 @@ void DrmBackend::moveCursor()
 
 QPainterBackend *DrmBackend::createQPainterBackend()
 {
-    m_gpus.at(0)->setDeleteBufferAfterPageFlip(false);
     return new DrmQPainterBackend(this, m_gpus.at(0));
 }
 

src/plugins/platforms/drm/drm_backend.h

@@ -61,8 +61,6 @@ public:
     void init() override;
     void prepareShutdown() override;
 
-    bool present(DrmBuffer *buffer, DrmOutput *output);
-
     Outputs outputs() const override;
     Outputs enabledOutputs() const override;
     QVector<DrmOutput*> drmOutputs() const {

src/plugins/platforms/drm/drm_buffer.h

@@ -23,6 +23,9 @@ public:
     virtual ~DrmBuffer() = default;
 
     virtual bool needsModeChange(DrmBuffer *b) const {Q_UNUSED(b) return false;}
+    virtual bool shouldDeleteAfterPageflip() const {
+        return false;
+    }
 
     quint32 bufferId() const {
         return m_bufferId;

src/plugins/platforms/drm/drm_buffer_gbm.h

@@ -40,6 +40,9 @@ public:
             return true;
         }
     }
+    bool shouldDeleteAfterPageflip() const override {
+        return true;
+    }
 
     bool hasBo() const {
         return m_bo != nullptr;

src/plugins/platforms/drm/drm_gpu.cpp

@@ -62,8 +62,6 @@ DrmGpu::DrmGpu(DrmBackend *backend, QByteArray devNode, int fd, int drmId) : m_b
     DrmScopedPointer<drmVersion> version(drmGetVersion(fd));
     m_useEglStreams = strstr(version->name, "nvidia-drm");
 
-    m_deleteBufferAfterPageFlip = !m_useEglStreams;
-
     m_socketNotifier = new QSocketNotifier(fd, QSocketNotifier::Read, this);
     connect(m_socketNotifier, &QSocketNotifier::activated, this, &DrmGpu::dispatchEvents);
 }

src/plugins/platforms/drm/drm_gpu.h

@@ -58,10 +58,6 @@ public:
         return m_useEglStreams;
     }
 
-    bool deleteBufferAfterPageFlip() const {
-        return m_deleteBufferAfterPageFlip;
-    }
-
     QByteArray devNode() const {
         return m_devNode;
     }
@@ -86,10 +82,6 @@ public:
         m_eglDisplay = display;
     }
 
-    void setDeleteBufferAfterPageFlip(bool deleteBuffer) {
-        m_deleteBufferAfterPageFlip = deleteBuffer;
-    }
-
     DrmDumbBuffer *createBuffer(const QSize &size) const {
         return new DrmDumbBuffer(m_fd, size);
     }
@@ -132,7 +124,6 @@ private:
     const int m_drmId;
     bool m_atomicModeSetting;
     bool m_useEglStreams;
-    bool m_deleteBufferAfterPageFlip;
     gbm_device* m_gbmDevice;
     EGLDisplay m_eglDisplay = EGL_NO_DISPLAY;
     clockid_t m_presentationClock;

src/plugins/platforms/drm/drm_object_crtc.cpp

@@ -67,7 +67,7 @@ bool DrmCrtc::initProps()
 
 void DrmCrtc::flipBuffer()
 {
-    if (m_currentBuffer && m_gpu->deleteBufferAfterPageFlip() && m_currentBuffer != m_nextBuffer) {
+    if (m_currentBuffer && m_currentBuffer->shouldDeleteAfterPageflip() && m_currentBuffer != m_nextBuffer) {
         delete m_currentBuffer;
     }
     m_currentBuffer = m_nextBuffer;
@@ -94,7 +94,7 @@ bool DrmCrtc::blank(DrmOutput *output)
     }
 
     if (output->setModeLegacy(m_blackBuffer)) {
-        if (m_currentBuffer && m_gpu->deleteBufferAfterPageFlip()) {
+        if (m_currentBuffer && m_currentBuffer->shouldDeleteAfterPageflip()) {
             delete m_currentBuffer;
             delete m_nextBuffer;
         }

src/plugins/platforms/drm/drm_object_plane.cpp

@@ -164,16 +164,11 @@ DrmPlane::Transformations DrmPlane::transformation()
 
 void DrmPlane::flipBuffer()
 {
-    m_current = m_next;
-    m_next = nullptr;
-}
-
-void DrmPlane::flipBufferWithDelete()
-{
-    if (m_current != m_next) {
+    if (m_current != m_next && m_current && m_current->shouldDeleteAfterPageflip()) {
         delete m_current;
     }
-    flipBuffer();
+    m_current = m_next;
+    m_next = nullptr;
 }
 
 }

src/plugins/platforms/drm/drm_object_plane.h

@@ -87,7 +87,6 @@ public:
     Transformations transformation();
 
     void flipBuffer();
-    void flipBufferWithDelete();
 
     Transformations supportedTransformations() const {
         return m_supportedTransformations;

src/plugins/platforms/drm/drm_output.cpp

@@ -70,7 +70,7 @@ void DrmOutput::teardown()
 
     if (m_primaryPlane) {
         // TODO: when having multiple planes, also clean up these
-        if (m_gpu->deleteBufferAfterPageFlip()) {
+        if (m_primaryPlane->current() && m_primaryPlane->current()->shouldDeleteAfterPageflip()) {
             delete m_primaryPlane->current();
         }
         m_primaryPlane->setCurrent(nullptr);
@@ -670,41 +670,23 @@ void DrmOutput::pageFlipped()
     if (!m_crtc) {
         return;
     }
-    // Egl based surface buffers get destroyed, QPainter based dumb buffers not
-    // TODO: split up DrmOutput in two for dumb and egl/gbm surface buffer compatible subclasses completely?
-    if (m_gpu->deleteBufferAfterPageFlip()) {
-        if (m_gpu->atomicModeSetting()) {
-            if (!m_primaryPlane->next()) {
-                // on manual vt switch
-                // TODO: when we later use overlay planes it might happen, that we have a page flip with only
-                //       damage on one of these, and therefore the primary plane has no next buffer
-                //       -> Then we don't want to return here!
-                if (m_primaryPlane->current()) {
-                    m_primaryPlane->current()->releaseGbm();
-                }
-                return;
-            }
-            for (DrmPlane *p : m_nextPlanesFlipList) {
-                p->flipBufferWithDelete();
-            }
-            m_nextPlanesFlipList.clear();
-        } else {
-            if (!m_crtc->next()) {
-                // on manual vt switch
-                if (DrmBuffer *b = m_crtc->current()) {
-                    b->releaseGbm();
-                }
+    if (m_gpu->atomicModeSetting()) {
+        if (!m_primaryPlane->next()) {
+            if (m_primaryPlane->current()) {
+                m_primaryPlane->current()->releaseGbm();
             }
-            m_crtc->flipBuffer();
+            return;
+        }
+        for (DrmPlane *p : m_nextPlanesFlipList) {
+            p->flipBuffer();
         }
+        m_nextPlanesFlipList.clear();
     } else {
-        if (m_gpu->atomicModeSetting()){
-            for (DrmPlane *p : m_nextPlanesFlipList) {
-                p->flipBuffer();
+        if (!m_crtc->next()) {
+            // on manual vt switch
+            if (DrmBuffer *b = m_crtc->current()) {
+                b->releaseGbm();
             }
-            m_nextPlanesFlipList.clear();
-        } else {
-            m_crtc->flipBuffer();
         }
         m_crtc->flipBuffer();
     }
@@ -716,14 +698,25 @@ void DrmOutput::pageFlipped()
 
 bool DrmOutput::present(DrmBuffer *buffer)
 {
+    if (!buffer || buffer->bufferId() == 0) {
+        if (buffer && buffer->shouldDeleteAfterPageflip()) {
+            delete buffer;
+        }
+        return false;
+    }
     if (m_dpmsModePending != DpmsMode::On) {
         return false;
     }
+    bool result;
     if (m_gpu->atomicModeSetting()) {
-        return presentAtomically(buffer);
+        result = presentAtomically(buffer);
     } else {
-        return presentLegacy(buffer);
+        result = presentLegacy(buffer);
+    }
+    if (!result && buffer->shouldDeleteAfterPageflip()) {
+        delete buffer;
     }
+    return result;
 }
 
 bool DrmOutput::dpmsAtomicOff()
@@ -976,8 +969,10 @@ bool DrmOutput::atomicReqModesetPopulate(drmModeAtomicReq *req, bool enable)
         m_primaryPlane->setValue(int(DrmPlane::PropertyIndex::CrtcH), targetRect.height());
         m_primaryPlane->setValue(int(DrmPlane::PropertyIndex::CrtcId), m_crtc->id());
     } else {
-        if (m_gpu->deleteBufferAfterPageFlip()) {
+        if (m_primaryPlane->current() && m_primaryPlane->current()->shouldDeleteAfterPageflip()) {
             delete m_primaryPlane->current();
+        }
+        if (m_primaryPlane->next() && m_primaryPlane->next()->shouldDeleteAfterPageflip()) {
             delete m_primaryPlane->next();
         }
         m_primaryPlane->setCurrent(nullptr);

src/plugins/platforms/drm/egl_gbm_backend.cpp

@@ -602,7 +602,7 @@ bool EglGbmBackend::presentOnOutput(Output &output, const QRegion &damagedRegion
     }
 
     Q_EMIT output.output->outputChange(damagedRegion);
-    if (!m_backend->present(output.buffer, output.output)) {
+    if (!output.output->present(output.buffer)) {
         return false;
     }
 

src/plugins/platforms/drm/egl_stream_backend.cpp

@@ -446,7 +446,7 @@ bool EglStreamBackend::presentOnOutput(EglStreamBackend::Output &o)
         return false;
     }
 
-    return m_backend->present(o.buffer, o.output);
+    return o.output->present(o.buffer);
 }
 
 SceneOpenGLTexturePrivate *EglStreamBackend::createBackendTexture(SceneOpenGLTexture *texture)

src/plugins/platforms/drm/scene_qpainter_drm_backend.cpp

@@ -114,7 +114,7 @@ void DrmQPainterBackend::endFrame(int screenId, int mask, const QRegion &damage)
     const Output &rendererOutput = m_outputs[screenId];
     DrmOutput *drmOutput = rendererOutput.output;
 
-    if (!m_backend->present(rendererOutput.buffer[rendererOutput.index], drmOutput)) {
+    if (!drmOutput->present(rendererOutput.buffer[rendererOutput.index])) {
         RenderLoopPrivate *renderLoopPrivate = RenderLoopPrivate::get(drmOutput->renderLoop());
         renderLoopPrivate->notifyFrameFailed();
     }