[platforms/drm] Disable transformations

Summary:
Rotation in the past was not working in the DRM backend reliable. Now on 5.17
it even freezes the KWin session, so for now we need to just disable it trying.

Test Plan:
Tried to change Rotation with KScreen. Nothing happened but session was still
usable afterwards.

Reviewers: #kwin

Subscribers: ngraham, jriddell, bshah, zzag, apol, kwin

Tags: #kwin

Differential Revision: https://phabricator.kde.org/D24112

plugins/platforms/drm/drm_output.cpp

@@ -633,6 +633,9 @@ bool DrmOutput::dpmsLegacyApply()
     return true;
 }
 
+// TODO: Rotation is currently broken in the DRM backend for 90° and 270°. Disable all rotation for
+// now to not break user setups until it is possible again.
+#if 0
 void DrmOutput::transform(KWayland::Server::OutputDeviceInterface::Transform transform)
 {
     waylandOutputDevice()->setTransform(transform);
@@ -710,6 +713,12 @@ void DrmOutput::transform(KWayland::Server::OutputDeviceInterface::Transform tra
     // TODO: are these calls not enough in updateMode already?
     setWaylandMode();
 }
+#else
+void DrmOutput::transform(KWayland::Server::OutputDeviceInterface::Transform transform)
+{
+    Q_UNUSED(transform)
+}
+#endif
 
 void DrmOutput::updateMode(int modeIndex)
 {