From c1312a555169c801b2c116a7b333443730092e07 Mon Sep 17 00:00:00 2001
From: Xaver Hugl <xaver.hugl@gmail.com>
Date: Wed, 8 Nov 2023 14:39:53 +0100
Subject: [PATCH] backends/drm: fix pageflip events getting lost when outputs
 get turned off

When a display gets turned off while a pageflip event was still pending, the pending
state gets changed immediately, without waiting for the pageflip event to arrive first.
When this happens, activePending() returns false, and so the pageflip event gets discarded.
This commit changes the logic to only check for activePending() when the pageflip is for a
modeset, avoiding that issue.

BUG: 476340
BUG: 476341
BUG: 476342
BUG: 437520
BUG: 475146
---
 src/backends/drm/drm_commit.cpp   | 12 ++++++++++--
 src/backends/drm/drm_commit.h     |  2 ++
 src/backends/drm/drm_pipeline.cpp |  7 +++++--
 src/backends/drm/drm_pipeline.h   |  3 ++-
 4 files changed, 19 insertions(+), 5 deletions(-)

diff --git a/src/backends/drm/drm_commit.cpp b/src/backends/drm/drm_commit.cpp
index de1285427d..a60df6e22a 100644
--- a/src/backends/drm/drm_commit.cpp
+++ b/src/backends/drm/drm_commit.cpp
@@ -83,6 +83,7 @@ bool DrmAtomicCommit::commit()
 
 bool DrmAtomicCommit::commitModeset()
 {
+    m_modeset = true;
     return doCommit(DRM_MODE_ATOMIC_ALLOW_MODESET);
 }
 
@@ -127,8 +128,14 @@ void DrmAtomicCommit::pageFlipped(std::chrono::nanoseconds timestamp) const
     for (const auto &[plane, buffer] : m_buffers) {
         plane->setCurrentBuffer(buffer);
     }
+    DrmPipeline::PageflipType type = DrmPipeline::PageflipType::Normal;
+    if (m_modeset) {
+        type = DrmPipeline::PageflipType::Modeset;
+    } else if (m_cursorOnly) {
+        type = DrmPipeline::PageflipType::CursorOnly;
+    }
     for (const auto pipeline : std::as_const(m_pipelines)) {
-        pipeline->pageFlipped(timestamp, m_cursorOnly ? DrmPipeline::PageflipType::CursorOnly : DrmPipeline::PageflipType::Normal);
+        pipeline->pageFlipped(timestamp, type);
     }
 }
 
@@ -190,6 +197,7 @@ DrmLegacyCommit::DrmLegacyCommit(DrmPipeline *pipeline, const std::shared_ptr<Dr
 
 bool DrmLegacyCommit::doModeset(DrmConnector *connector, DrmConnectorMode *mode)
 {
+    m_modeset = true;
     uint32_t connectorId = connector->id();
     if (drmModeSetCrtc(gpu()->fd(), m_pipeline->crtc()->id(), m_buffer->framebufferId(), 0, 0, &connectorId, 1, mode->nativeMode()) == 0) {
         m_pipeline->crtc()->setCurrent(m_buffer);
@@ -208,6 +216,6 @@ void DrmLegacyCommit::pageFlipped(std::chrono::nanoseconds timestamp) const
 {
     Q_ASSERT(QThread::currentThread() == QApplication::instance()->thread());
     m_pipeline->crtc()->setCurrent(m_buffer);
-    m_pipeline->pageFlipped(timestamp, DrmPipeline::PageflipType::Normal);
+    m_pipeline->pageFlipped(timestamp, m_modeset ? DrmPipeline::PageflipType::Modeset : DrmPipeline::PageflipType::Normal);
 }
 }
diff --git a/src/backends/drm/drm_commit.h b/src/backends/drm/drm_commit.h
index b9c5a9e792..04548ee13e 100644
--- a/src/backends/drm/drm_commit.h
+++ b/src/backends/drm/drm_commit.h
@@ -88,6 +88,7 @@ private:
     std::optional<bool> m_vrr;
     std::unordered_map<uint32_t /* object */, std::unordered_map<uint32_t /* property */, uint64_t /* value */>> m_properties;
     bool m_cursorOnly = false;
+    bool m_modeset = false;
 };
 
 class DrmLegacyCommit : public DrmCommit
@@ -102,6 +103,7 @@ public:
 private:
     DrmPipeline *const m_pipeline;
     const std::shared_ptr<DrmFramebuffer> m_buffer;
+    bool m_modeset = false;
 };
 
 }
diff --git a/src/backends/drm/drm_pipeline.cpp b/src/backends/drm/drm_pipeline.cpp
index c24fa31c3a..f6b27b99a5 100644
--- a/src/backends/drm/drm_pipeline.cpp
+++ b/src/backends/drm/drm_pipeline.cpp
@@ -424,8 +424,11 @@ void DrmPipeline::pageFlipped(std::chrono::nanoseconds timestamp, PageflipType t
 {
     m_commitThread->pageFlipped(timestamp);
     m_legacyPageflipPending = false;
-    if (m_output && activePending()) {
-        if (type == PageflipType::Normal) {
+    if (type == PageflipType::Modeset && !activePending()) {
+        return;
+    }
+    if (m_output) {
+        if (type == PageflipType::Normal || type == PageflipType::Modeset) {
             m_output->pageFlipped(timestamp);
         } else {
             RenderLoopPrivate::get(m_output->renderLoop())->notifyVblank(timestamp);
diff --git a/src/backends/drm/drm_pipeline.h b/src/backends/drm/drm_pipeline.h
index e1d03788eb..ec4432613f 100644
--- a/src/backends/drm/drm_pipeline.h
+++ b/src/backends/drm/drm_pipeline.h
@@ -85,7 +85,8 @@ public:
 
     enum class PageflipType {
         Normal,
-        CursorOnly
+        CursorOnly,
+        Modeset,
     };
     void pageFlipped(std::chrono::nanoseconds timestamp, PageflipType type);
     bool pageflipsPending() const;