From 52c1155b26ba8bf21a1955a3846c4f2553558c29 Mon Sep 17 00:00:00 2001
From: Xaver Hugl <xaver.hugl@gmail.com>
Date: Fri, 8 Apr 2022 17:37:48 +0200
Subject: [PATCH] backends/drm: prevent calling frameFailed multiple times per
 present

---
 src/backends/drm/drm_output.cpp   |  7 ++++---
 src/backends/drm/drm_pipeline.cpp | 10 ++++++----
 src/backends/drm/drm_pipeline.h   |  1 +
 3 files changed, 11 insertions(+), 7 deletions(-)

diff --git a/src/backends/drm/drm_output.cpp b/src/backends/drm/drm_output.cpp
index 5a9243a662..48f60e77ef 100644
--- a/src/backends/drm/drm_output.cpp
+++ b/src/backends/drm/drm_output.cpp
@@ -320,14 +320,15 @@ bool DrmOutput::present()
             setVrrPolicy(RenderLoop::VrrPolicy::Never);
         }
     }
-    if (m_pipeline->present()) {
+    bool modeset = gpu()->needsModeset();
+    if (modeset ? m_pipeline->maybeModeset() : m_pipeline->present()) {
         Q_EMIT outputChange(m_pipeline->pending.layer->currentDamage());
         return true;
-    } else {
+    } else if (!modeset) {
         qCWarning(KWIN_DRM) << "Presentation failed!" << strerror(errno);
         frameFailed();
-        return false;
     }
+    return false;
 }
 
 int DrmOutput::gammaRampSize() const
diff --git a/src/backends/drm/drm_pipeline.cpp b/src/backends/drm/drm_pipeline.cpp
index 4c4bff5d71..fc314c663b 100644
--- a/src/backends/drm/drm_pipeline.cpp
+++ b/src/backends/drm/drm_pipeline.cpp
@@ -61,10 +61,6 @@ bool DrmPipeline::testScanout()
 bool DrmPipeline::present()
 {
     Q_ASSERT(pending.crtc);
-    if (gpu()->needsModeset()) {
-        m_modesetPresentPending = true;
-        return gpu()->maybeModeset();
-    }
     if (gpu()->atomicModeSetting()) {
         return commitPipelines({this}, CommitMode::Commit);
     } else {
@@ -79,6 +75,12 @@ bool DrmPipeline::present()
     return true;
 }
 
+bool DrmPipeline::maybeModeset()
+{
+    m_modesetPresentPending = true;
+    return gpu()->maybeModeset();
+}
+
 bool DrmPipeline::commitPipelines(const QVector<DrmPipeline *> &pipelines, CommitMode mode, const QVector<DrmObject *> &unusedObjects)
 {
     Q_ASSERT(!pipelines.isEmpty());
diff --git a/src/backends/drm/drm_pipeline.h b/src/backends/drm/drm_pipeline.h
index 7f2065d752..11783de44a 100644
--- a/src/backends/drm/drm_pipeline.h
+++ b/src/backends/drm/drm_pipeline.h
@@ -63,6 +63,7 @@ public:
      */
     bool present();
     bool testScanout();
+    bool maybeModeset();
 
     bool needsModeset() const;
     void applyPendingChanges();