From 47c08d6f6660e71747c32e45c4dd3ac1eb9251c2 Mon Sep 17 00:00:00 2001
From: Xaver Hugl <xaver.hugl@gmail.com>
Date: Fri, 24 Jun 2022 02:52:32 +0200
Subject: [PATCH] backends/drm: ensure modeset properties are reset properly

Without this, all atomic modeset commits fail on setups with a VR headset
---
 src/backends/drm/drm_pipeline.cpp | 9 +++++++--
 src/backends/drm/drm_pipeline.h   | 1 +
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/src/backends/drm/drm_pipeline.cpp b/src/backends/drm/drm_pipeline.cpp
index be3ec02199..540b6ce634 100644
--- a/src/backends/drm/drm_pipeline.cpp
+++ b/src/backends/drm/drm_pipeline.cpp
@@ -170,13 +170,17 @@ DrmPipeline::Error DrmPipeline::commitPipelinesAtomic(const QVector<DrmPipeline
 
 DrmPipeline::Error DrmPipeline::populateAtomicValues(drmModeAtomicReq *req, uint32_t &flags)
 {
-    if (needsModeset()) {
-        prepareAtomicModeset();
+    bool modeset = needsModeset();
+    if (modeset) {
         flags |= DRM_MODE_ATOMIC_ALLOW_MODESET;
+        m_pending.needsModeset = true;
     }
     if (activePending()) {
         flags |= DRM_MODE_PAGE_FLIP_EVENT;
     }
+    if (m_pending.needsModeset) {
+        prepareAtomicModeset();
+    }
     if (m_pending.crtc) {
         m_pending.crtc->setPending(DrmCrtc::PropertyIndex::VrrEnabled, m_pending.syncMode == RenderLoopPrivate::SyncMode::Adaptive);
         m_pending.crtc->setPending(DrmCrtc::PropertyIndex::Gamma_LUT, m_pending.gamma ? m_pending.gamma->blobId() : 0);
@@ -302,6 +306,7 @@ void DrmPipeline::atomicCommitSuccessful(CommitMode mode)
         }
     }
     if (mode != CommitMode::Test) {
+        m_pending.needsModeset = false;
         if (activePending()) {
             m_pageflipPending = true;
         }
diff --git a/src/backends/drm/drm_pipeline.h b/src/backends/drm/drm_pipeline.h
index 3ca5e5397d..8c29fbedaf 100644
--- a/src/backends/drm/drm_pipeline.h
+++ b/src/backends/drm/drm_pipeline.h
@@ -173,6 +173,7 @@ private:
         QMap<uint32_t, QVector<uint64_t>> formats;
         bool active = true; // whether or not the pipeline should be currently used
         bool enabled = true; // whether or not the pipeline needs a crtc
+        bool needsModeset = false;
         std::shared_ptr<DrmConnectorMode> mode;
         uint32_t overscan = 0;
         Output::RgbRange rgbRange = Output::RgbRange::Automatic;