From fe9a3f45c0c7452da41776d17fc2088fa5789f97 Mon Sep 17 00:00:00 2001
From: Xaver Hugl <xaver.hugl@gmail.com>
Date: Fri, 14 Jan 2022 20:05:23 +0100
Subject: [PATCH] backends/drm: ensure correct format+modifiers pairs for
 surfaces

When the crtcs get switched around between outputs, their primary
planes and thus the supported formats also get switched around. In
order to make sure that doesn't cause any problems, always check
whether or not the format+modifiers used are supported.
---
 src/backends/drm/egl_gbm_backend.cpp | 4 ++++
 src/backends/drm/gbm_surface.cpp     | 6 ++++++
 src/backends/drm/gbm_surface.h       | 2 ++
 3 files changed, 12 insertions(+)

diff --git a/src/backends/drm/egl_gbm_backend.cpp b/src/backends/drm/egl_gbm_backend.cpp
index 368ca53e0b..ec64ea2426 100644
--- a/src/backends/drm/egl_gbm_backend.cpp
+++ b/src/backends/drm/egl_gbm_backend.cpp
@@ -552,6 +552,10 @@ bool EglGbmBackend::doesRenderFit(const Output &output, const Output::RenderData
     if (output.forceXrgb8888 && render.gbmSurface->format() != DRM_FORMAT_XRGB8888) {
         return false;
     }
+    if (!output.output->isFormatSupported(render.gbmSurface->format())
+        || output.output->supportedModifiers(render.gbmSurface->format()) != render.gbmSurface->modifiers()) {
+        return false;
+    }
     QSize surfaceSize = output.output->bufferSize();
     if (surfaceSize != render.gbmSurface->size()) {
         return false;
diff --git a/src/backends/drm/gbm_surface.cpp b/src/backends/drm/gbm_surface.cpp
index 595c7da4bd..c0248c10e4 100644
--- a/src/backends/drm/gbm_surface.cpp
+++ b/src/backends/drm/gbm_surface.cpp
@@ -40,6 +40,7 @@ GbmSurface::GbmSurface(DrmGpu *gpu, const QSize &size, uint32_t format, QVector<
     , m_gpu(gpu)
     , m_size(size)
     , m_format(format)
+    , m_modifiers(modifiers)
 {
     if (!m_surface) {
         qCCritical(KWIN_DRM) << "Could not create gbm surface!" << strerror(errno);
@@ -138,4 +139,9 @@ uint32_t GbmSurface::format() const
     return m_format;
 }
 
+QVector<uint64_t> GbmSurface::modifiers() const
+{
+    return m_modifiers;
+}
+
 }
diff --git a/src/backends/drm/gbm_surface.h b/src/backends/drm/gbm_surface.h
index 60c1420b41..f2e8a51f1c 100644
--- a/src/backends/drm/gbm_surface.h
+++ b/src/backends/drm/gbm_surface.h
@@ -40,6 +40,7 @@ public:
     QSize size() const;
     bool isValid() const;
     uint32_t format() const;
+    QVector<uint64_t> modifiers() const;
 
 private:
     gbm_surface *m_surface;
@@ -47,6 +48,7 @@ private:
     EGLSurface m_eglSurface = EGL_NO_SURFACE;
     QSize m_size;
     const uint32_t m_format;
+    const QVector<uint64_t> m_modifiers;
 
     QSharedPointer<GbmBuffer> m_currentBuffer;
     QSharedPointer<DrmGbmBuffer> m_currentDrmBuffer;