Detect some DrmConnector properties and ignore non-desktop displays

BUG: 419032

plugins/platforms/drm/drm_gpu.cpp

@@ -135,6 +135,10 @@ bool DrmGpu::updateOutputs()
                 delete c;
                 continue;
             }
+            if (c->isNonDesktop()) {
+                delete c;
+                continue;
+            }
             m_connectors << c;
         } else {
             oldConnectors.removeOne(*it);

plugins/platforms/drm/drm_object.cpp

@@ -47,7 +47,7 @@ void DrmObject::initProp(int n, drmModeObjectProperties *properties, QVector<QBy
         }
 
         if (prop->name == m_propsNames[n]) {
-            qCDebug(KWIN_DRM).nospace() << m_id << ": " << prop->name << "' (id " << prop->prop_id
+            qCDebug(KWIN_DRM).nospace() << m_id << ": '" << prop->name << "' (id " << prop->prop_id
                               << "): " << properties->prop_values[i];
             m_props[n] = new Property(prop.data(), properties->prop_values[i], enumNames);
             return;
@@ -67,7 +67,7 @@ bool DrmObject::doAtomicPopulate(drmModeAtomicReq *req, int firstProperty) const
 
     for (int i = firstProperty; i < m_props.size(); i++) {
         auto property = m_props.at(i);
-        if (!property) {
+        if (!property || property->isImmutable()) {
             continue;
         }
         ret &= atomicAddProperty(req, property);
@@ -113,6 +113,7 @@ DrmObject::Property::Property(drmModePropertyRes *prop, uint64_t val, QVector<QB
     : m_propId(prop->prop_id)
     , m_propName(prop->name)
     , m_value(val)
+    , m_immutable(prop->flags & DRM_MODE_PROP_IMMUTABLE)
 {
     if (!enumNames.isEmpty()) {
         qCDebug(KWIN_DRM) << m_propName << " can have enums:" << enumNames;

plugins/platforms/drm/drm_object.h

@@ -122,6 +122,9 @@ protected:
         const QByteArray &name() const {
             return m_propName;
         }
+        bool isImmutable() const {
+            return m_immutable;
+        }
 
     private:
         uint32_t m_propId = 0;
@@ -130,6 +133,7 @@ protected:
         uint64_t m_value = 0;
         QVector<uint64_t> m_enumMap;
         QVector<QByteArray> m_enumNames;
+        bool m_immutable = false;
     };
 
 private:

plugins/platforms/drm/drm_object_connector.cpp

@@ -41,6 +41,7 @@ bool DrmConnector::initProps()
 {
     setPropertyNames( {
         QByteArrayLiteral("CRTC_ID"),
+        QByteArrayLiteral("non-desktop")
     });
 
     DrmScopedPointer<drmModeObjectProperties> properties(

plugins/platforms/drm/drm_object_connector.h

@@ -25,6 +25,7 @@ public:
 
     enum class PropertyIndex {
         CrtcId = 0,
+        NonDesktop = 1,
         Count
     };
 
@@ -34,8 +35,10 @@ public:
     
     bool initProps() override;
     bool isConnected();
-
-
+    
+    bool isNonDesktop() const {
+        return m_props.at(static_cast<int>(PropertyIndex::NonDesktop))->value();
+    }
 private:
     QVector<uint32_t> m_encoders;
 };