From 4610a916d3da5d2ed499172ef9809ce6204cf5b5 Mon Sep 17 00:00:00 2001
From: Xaver Hugl <xaver.hugl@gmail.com>
Date: Fri, 28 Jul 2023 15:36:34 +0200
Subject: [PATCH] backends/drm: handle atomic commits failing correctly

If the pending pageflip flag is not reset, KWin will wait for a pageflip that
never comes
---
 src/backends/drm/drm_commit_thread.cpp |  2 ++
 src/backends/drm/drm_pipeline.cpp      | 12 ++++++------
 2 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/src/backends/drm/drm_commit_thread.cpp b/src/backends/drm/drm_commit_thread.cpp
index 1dd23eb9db..ecf91efa7d 100644
--- a/src/backends/drm/drm_commit_thread.cpp
+++ b/src/backends/drm/drm_commit_thread.cpp
@@ -9,6 +9,7 @@
 #include "drm_commit_thread.h"
 #include "drm_commit.h"
 #include "drm_gpu.h"
+#include "logging_p.h"
 #include "utils/realtime.h"
 
 namespace KWin
@@ -42,6 +43,7 @@ DrmCommitThread::DrmCommitThread()
                     // the atomic commit takes ownership of the object
                     m_commit.release();
                 } else {
+                    qCWarning(KWIN_DRM) << "atomic commit failed:" << strerror(errno);
                     m_droppedCommits.push_back(std::move(m_commit));
                     QMetaObject::invokeMethod(this, &DrmCommitThread::commitFailed, Qt::ConnectionType::QueuedConnection);
                     QMetaObject::invokeMethod(this, &DrmCommitThread::clearDroppedCommits, Qt::ConnectionType::QueuedConnection);
diff --git a/src/backends/drm/drm_pipeline.cpp b/src/backends/drm/drm_pipeline.cpp
index d14cede697..cbfc1cf2df 100644
--- a/src/backends/drm/drm_pipeline.cpp
+++ b/src/backends/drm/drm_pipeline.cpp
@@ -41,6 +41,12 @@ DrmPipeline::DrmPipeline(DrmConnector *conn)
     : m_connector(conn)
     , m_commitThread(std::make_unique<DrmCommitThread>())
 {
+    QObject::connect(m_commitThread.get(), &DrmCommitThread::commitFailed, [this]() {
+        m_pageflipPending = false;
+        if (m_output) {
+            m_output->frameFailed();
+        }
+    });
 }
 
 DrmPipeline::~DrmPipeline()
@@ -421,13 +427,7 @@ void DrmPipeline::pageFlipped(std::chrono::nanoseconds timestamp)
 
 void DrmPipeline::setOutput(DrmOutput *output)
 {
-    if (m_output) {
-        QObject::disconnect(m_commitThread.get(), nullptr, m_output, nullptr);
-    }
     m_output = output;
-    if (output) {
-        QObject::connect(m_commitThread.get(), &DrmCommitThread::commitFailed, output, &DrmAbstractOutput::frameFailed);
-    }
 }
 
 DrmOutput *DrmPipeline::output() const