diff --git a/plugins/platforms/drm/drm_backend.cpp b/plugins/platforms/drm/drm_backend.cpp
index 164197192..3d2bef32a 100644
--- a/plugins/platforms/drm/drm_backend.cpp
+++ b/plugins/platforms/drm/drm_backend.cpp
@@ -1,728 +1,728 @@
 /********************************************************************
  KWin - the KDE window manager
  This file is part of the KDE project.
 
 Copyright (C) 2015 Martin Gräßlin <mgraesslin@kde.org>
 
 This program is free software; you can redistribute it and/or modify
 it under the terms of the GNU General Public License as published by
 the Free Software Foundation; either version 2 of the License, or
 (at your option) any later version.
 
 This program is distributed in the hope that it will be useful,
 but WITHOUT ANY WARRANTY; without even the implied warranty of
 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 GNU General Public License for more details.
 
 You should have received a copy of the GNU General Public License
 along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *********************************************************************/
 #include "drm_backend.h"
 #include "drm_output.h"
 #include "drm_object_connector.h"
 #include "drm_object_crtc.h"
 #include "drm_object_plane.h"
 #include "composite.h"
 #include "cursor.h"
 #include "logging.h"
 #include "logind.h"
 #include "main.h"
 #include "scene_qpainter_drm_backend.h"
 #include "screens_drm.h"
 #include "udev.h"
 #include "wayland_server.h"
 #if HAVE_GBM
 #include "egl_gbm_backend.h"
 #include <gbm.h>
 #endif
 // KWayland
 #include <KWayland/Server/seat_interface.h>
 #include <KWayland/Server/outputconfiguration_interface.h>
 // KF5
 #include <KConfigGroup>
 #include <KLocalizedString>
 #include <KSharedConfig>
 // Qt
 #include <QCryptographicHash>
 #include <QSocketNotifier>
 #include <QPainter>
 // system
 #include <unistd.h>
 // drm
 #include <xf86drm.h>
 #include <xf86drmMode.h>
 #include <libdrm/drm_mode.h>
 
 #ifndef DRM_CAP_CURSOR_WIDTH
 #define DRM_CAP_CURSOR_WIDTH 0x8
 #endif
 
 #ifndef DRM_CAP_CURSOR_HEIGHT
 #define DRM_CAP_CURSOR_HEIGHT 0x9
 #endif
 
 #define KWIN_DRM_EVENT_CONTEXT_VERSION 2
 
 namespace KWin
 {
 
 DrmBackend::DrmBackend(QObject *parent)
     : Platform(parent)
     , m_udev(new Udev)
     , m_udevMonitor(m_udev->monitor())
     , m_dpmsFilter()
 {
     handleOutputs();
     m_cursor[0] = nullptr;
     m_cursor[1] = nullptr;
 }
 
 DrmBackend::~DrmBackend()
 {
 #if HAVE_GBM
     if (m_gbmDevice) {
         gbm_device_destroy(m_gbmDevice);
     }
 #endif
     if (m_fd >= 0) {
         // wait for pageflips
         while (m_pageFlipsPending != 0) {
             QCoreApplication::processEvents(QEventLoop::WaitForMoreEvents);
         }
         qDeleteAll(m_outputs);
         qDeleteAll(m_planes);
         qDeleteAll(m_crtcs);
         qDeleteAll(m_connectors);
         delete m_cursor[0];
         delete m_cursor[1];
         close(m_fd);
     }
 }
 
 void DrmBackend::init()
 {
     LogindIntegration *logind = LogindIntegration::self();
     auto takeControl = [logind, this]() {
         if (logind->hasSessionControl()) {
             openDrm();
         } else {
             logind->takeControl();
             connect(logind, &LogindIntegration::hasSessionControlChanged, this, &DrmBackend::openDrm);
         }
     };
     if (logind->isConnected()) {
         takeControl();
     } else {
         connect(logind, &LogindIntegration::connectedChanged, this, takeControl);
     }
 }
 
 void DrmBackend::outputWentOff()
 {
     if (!m_dpmsFilter.isNull()) {
         // already another output is off
         return;
     }
     m_dpmsFilter.reset(new DpmsInputEventFilter(this));
     input()->prependInputEventFilter(m_dpmsFilter.data());
 }
 
 void DrmBackend::turnOutputsOn()
 {
     m_dpmsFilter.reset();
     for (auto it = m_outputs.constBegin(), end = m_outputs.constEnd(); it != end; it++) {
         (*it)->setDpms(DrmOutput::DpmsMode::On);
     }
 }
 
 void DrmBackend::checkOutputsAreOn()
 {
     if (m_dpmsFilter.isNull()) {
         // already disabled, all outputs are on
         return;
     }
     for (auto it = m_outputs.constBegin(), end = m_outputs.constEnd(); it != end; it++) {
         if (!(*it)->isDpmsEnabled()) {
             // dpms still disabled, need to keep the filter
             return;
         }
     }
     // all outputs are on, disable the filter
     m_dpmsFilter.reset();
 }
 
 void DrmBackend::activate(bool active)
 {
     if (active) {
         qCDebug(KWIN_DRM) << "Activating session.";
         reactivate();
     } else {
         qCDebug(KWIN_DRM) << "Deactivating session.";
         deactivate();
     }
 }
 
 void DrmBackend::reactivate()
 {
     if (m_active) {
         return;
     }
     m_active = true;
     if (!usesSoftwareCursor()) {
         DrmDumbBuffer *c = m_cursor[(m_cursorIndex + 1) % 2];
         const QPoint cp = Cursor::pos() - softwareCursorHotspot();
         for (auto it = m_outputs.constBegin(); it != m_outputs.constEnd(); ++it) {
             DrmOutput *o = *it;
             // only relevant in atomic mode
             o->m_modesetRequested = true;
             o->pageFlipped();   // TODO: Do we really need this?
             o->m_crtc->blank();
             o->showCursor(c);
             o->moveCursor(cp);
         }
     }
     // restart compositor
     m_pageFlipsPending = 0;
     if (Compositor *compositor = Compositor::self()) {
         compositor->bufferSwapComplete();
         compositor->addRepaintFull();
     }
 }
 
 void DrmBackend::deactivate()
 {
     if (!m_active) {
         return;
     }
     // block compositor
     if (m_pageFlipsPending == 0 && Compositor::self()) {
         Compositor::self()->aboutToSwapBuffers();
     }
     // hide cursor and disable
     for (auto it = m_outputs.constBegin(); it != m_outputs.constEnd(); ++it) {
         DrmOutput *o = *it;
         o->hideCursor();
     }
     m_active = false;
 }
 
 void DrmBackend::pageFlipHandler(int fd, unsigned int frame, unsigned int sec, unsigned int usec, void *data)
 {
     Q_UNUSED(fd)
     Q_UNUSED(frame)
     Q_UNUSED(sec)
     Q_UNUSED(usec)
     auto output = reinterpret_cast<DrmOutput*>(data);
     output->pageFlipped();
     output->m_backend->m_pageFlipsPending--;
     if (output->m_backend->m_pageFlipsPending == 0) {
         // TODO: improve, this currently means we wait for all page flips or all outputs.
         // It would be better to driver the repaint per output
 
         if (output->m_dpmsAtomicOffPending) {
             output->m_modesetRequested = true;
             output->dpmsAtomicOff();
         }
 
         if (Compositor::self()) {
             Compositor::self()->bufferSwapComplete();
         }
     }
 }
 
 void DrmBackend::openDrm()
 {
     connect(LogindIntegration::self(), &LogindIntegration::sessionActiveChanged, this, &DrmBackend::activate);
     UdevDevice::Ptr device = m_udev->primaryGpu();
     if (!device) {
         qCWarning(KWIN_DRM) << "Did not find a GPU";
         return;
     }
     int fd = LogindIntegration::self()->takeDevice(device->devNode());
     if (fd < 0) {
         qCWarning(KWIN_DRM) << "failed to open drm device at" << device->devNode();
         return;
     }
     m_fd = fd;
     m_active = true;
     QSocketNotifier *notifier = new QSocketNotifier(m_fd, QSocketNotifier::Read, this);
     connect(notifier, &QSocketNotifier::activated, this,
         [this] {
             if (!LogindIntegration::self()->isActiveSession()) {
                 return;
             }
             drmEventContext e;
             memset(&e, 0, sizeof e);
             e.version = KWIN_DRM_EVENT_CONTEXT_VERSION;
             e.page_flip_handler = pageFlipHandler;
             drmHandleEvent(m_fd, &e);
         }
     );
     m_drmId = device->sysNum();
 
     // trying to activate Atomic Mode Setting (this means also Universal Planes)
-    if (qEnvironmentVariableIsSet("KWIN_DRM_AMS")) {
+    if (!qEnvironmentVariableIsSet("KWIN_DRM_NO_AMS")) {
         if (drmSetClientCap(m_fd, DRM_CLIENT_CAP_ATOMIC, 1) == 0) {
             qCDebug(KWIN_DRM) << "Using Atomic Mode Setting.";
             m_atomicModeSetting = true;
 
             ScopedDrmPointer<drmModePlaneRes, &drmModeFreePlaneResources> planeResources(drmModeGetPlaneResources(m_fd));
             if (!planeResources) {
                 qCWarning(KWIN_DRM) << "Failed to get plane resources. Falling back to legacy mode";
                 m_atomicModeSetting = false;
             }
 
             if (m_atomicModeSetting) {
                 qCDebug(KWIN_DRM) << "Number of planes:" << planeResources->count_planes;
 
                 // create the plane objects
                 for (unsigned int i = 0; i < planeResources->count_planes; ++i) {
                     drmModePlane *kplane = drmModeGetPlane(m_fd, planeResources->planes[i]);
                     DrmPlane *p = new DrmPlane(kplane->plane_id, this);
                     if (p->atomicInit()) {
                         m_planes << p;
                         if (p->type() == DrmPlane::TypeIndex::Overlay) {
                             m_overlayPlanes << p;
                         }
                     } else {
                         delete p;
                     }
                 }
 
                 if (m_planes.isEmpty()) {
                     qCWarning(KWIN_DRM) << "Failed to create any plane. Falling back to legacy mode";
                     m_atomicModeSetting = false;
                 }
             }
         } else {
             qCWarning(KWIN_DRM) << "drmSetClientCap for Atomic Mode Setting failed. Using legacy mode.";
         }
     }
 
     ScopedDrmPointer<_drmModeRes, &drmModeFreeResources> resources(drmModeGetResources(m_fd));
     drmModeRes *res = resources.data();
     if (!resources) {
         qCWarning(KWIN_DRM) << "drmModeGetResources failed";
         return;
     }
 
     for (int i = 0; i < res->count_connectors; ++i) {
         m_connectors << new DrmConnector(res->connectors[i], this);
     }
     for (int i = 0; i < res->count_crtcs; ++i) {
         m_crtcs << new DrmCrtc(res->crtcs[i], this, i);
     }
 
     if (m_atomicModeSetting) {
         auto tryAtomicInit = [] (DrmObject *obj) -> bool {
             if (obj->atomicInit()) {
                 return false;
             } else {
                 delete obj;
                 return true;
             }
         };
         m_connectors.erase(std::remove_if(m_connectors.begin(), m_connectors.end(), tryAtomicInit), m_connectors.end());
         m_crtcs.erase(std::remove_if(m_crtcs.begin(), m_crtcs.end(), tryAtomicInit), m_crtcs.end());
     }
 
     updateOutputs();
 
     if (m_outputs.isEmpty()) {
         qCWarning(KWIN_DRM) << "No outputs, cannot render, will terminate now";
         emit initFailed();
         return;
     }
 
     // setup udevMonitor
     if (m_udevMonitor) {
         m_udevMonitor->filterSubsystemDevType("drm");
         const int fd = m_udevMonitor->fd();
         if (fd != -1) {
             QSocketNotifier *notifier = new QSocketNotifier(fd, QSocketNotifier::Read, this);
             connect(notifier, &QSocketNotifier::activated, this,
                 [this] {
                     auto device = m_udevMonitor->getDevice();
                     if (!device) {
                         return;
                     }
                     if (device->sysNum() != m_drmId) {
                         return;
                     }
                     if (device->hasProperty("HOTPLUG", "1")) {
                         qCDebug(KWIN_DRM) << "Received hot plug event for monitored drm device";
                         updateOutputs();
                         m_cursorIndex = (m_cursorIndex + 1) % 2;
                         updateCursor();
                     }
                 }
             );
             m_udevMonitor->enable();
         }
     }
     setReady(true);
 
     initCursor();
 }
 
 void DrmBackend::updateOutputs()
 {
     if (m_fd < 0) {
         return;
     }
 
     ScopedDrmPointer<_drmModeRes, &drmModeFreeResources> resources(drmModeGetResources(m_fd));
     if (!resources) {
         qCWarning(KWIN_DRM) << "drmModeGetResources failed";
         return;
     }
 
     QVector<DrmOutput*> connectedOutputs;
     QVector<DrmConnector*> pendingConnectors;
 
     // split up connected connectors in already or not yet assigned ones
     for (DrmConnector *con : qAsConst(m_connectors)) {
         if (!con->isConnected()) {
             continue;
         }
 
         if (DrmOutput *o = findOutput(con->id())) {
             connectedOutputs << o;
         } else {
             pendingConnectors << con;
         }
     }
 
     // check for outputs which got removed
     auto it = m_outputs.begin();
     while (it != m_outputs.end()) {
         if (connectedOutputs.contains(*it)) {
             it++;
             continue;
         }
         DrmOutput *removed = *it;
         it = m_outputs.erase(it);
         emit outputRemoved(removed);
         delete removed;
     }
 
     // now check new connections
     for (DrmConnector *con : qAsConst(pendingConnectors)) {
         ScopedDrmPointer<_drmModeConnector, &drmModeFreeConnector> connector(drmModeGetConnector(m_fd, con->id()));
         if (!connector) {
             continue;
         }
         if (connector->count_modes == 0) {
             continue;
         }
         bool outputDone = false;
 
         QVector<uint32_t> encoders = con->encoders();
         for (auto encId : qAsConst(encoders)) {
             ScopedDrmPointer<_drmModeEncoder, &drmModeFreeEncoder> encoder(drmModeGetEncoder(m_fd, encId));
             if (!encoder) {
                 continue;
             }
             for (DrmCrtc *crtc : qAsConst(m_crtcs)) {
                 if (!(encoder->possible_crtcs & (1 << crtc->resIndex()))) {
                         continue;
                 }
 
                 // check if crtc isn't used yet -- currently we don't allow multiple outputs on one crtc (cloned mode)
                 auto it = std::find_if(connectedOutputs.constBegin(), connectedOutputs.constEnd(),
                     [crtc] (DrmOutput *o) {
                         return o->m_crtc == crtc;
                     }
                 );
                 if (it != connectedOutputs.constEnd()) {
                     continue;
                 }
 
                 // we found a suitable encoder+crtc
                 // TODO: we could avoid these lib drm calls if we store all struct data in DrmCrtc and DrmConnector in the beginning
                 ScopedDrmPointer<_drmModeCrtc, &drmModeFreeCrtc> modeCrtc(drmModeGetCrtc(m_fd, crtc->id()));
                 if (!modeCrtc) {
                     continue;
                 }
 
                 DrmOutput *output = new DrmOutput(this);
                 con->setOutput(output);
                 output->m_conn = con;
                 crtc->setOutput(output);
                 output->m_crtc = crtc;
                 connect(output, &DrmOutput::dpmsChanged, this, &DrmBackend::outputDpmsChanged);
 
                 if (modeCrtc->mode_valid) {
                     output->m_mode = modeCrtc->mode;
                 } else {
                     output->m_mode = connector->modes[0];
                 }
                 qCDebug(KWIN_DRM) << "For new output use mode " << output->m_mode.name;
 
                 if (!output->init(connector.data())) {
                     qCWarning(KWIN_DRM) << "Failed to create output for connector " << con->id();
                     con->setOutput(nullptr);
                     crtc->setOutput(nullptr);
                     delete output;
                     continue;
                 }
                 qCDebug(KWIN_DRM) << "Found new output with uuid" << output->uuid();
 
                 connectedOutputs << output;
                 emit outputAdded(output);
                 outputDone = true;
                 break;
             }
             if (outputDone) {
                 break;
             }
         }
     }
     std::sort(connectedOutputs.begin(), connectedOutputs.end(), [] (DrmOutput *a, DrmOutput *b) { return a->m_conn->id() < b->m_conn->id(); });
     m_outputs = connectedOutputs;
     readOutputsConfiguration();
     if (!m_outputs.isEmpty()) {
         emit screensQueried();
     }
 }
 
 void DrmBackend::readOutputsConfiguration()
 {
     if (m_outputs.isEmpty()) {
         return;
     }
     const QByteArray uuid = generateOutputConfigurationUuid();
     const auto outputGroup = kwinApp()->config()->group("DrmOutputs");
     const auto configGroup = outputGroup.group(uuid);
     // default position goes from left to right
     QPoint pos(0, 0);
     for (auto it = m_outputs.begin(); it != m_outputs.end(); ++it) {
         qCDebug(KWIN_DRM) << "Reading output configuration for [" << uuid << "] ["<< (*it)->uuid() << "]";
         const auto outputConfig = configGroup.group((*it)->uuid());
         (*it)->setGlobalPos(outputConfig.readEntry<QPoint>("Position", pos));
         // TODO: add mode
         (*it)->setScale(outputConfig.readEntry("Scale", 1.0));
         pos.setX(pos.x() + (*it)->geometry().width());
     }
 }
 
 QByteArray DrmBackend::generateOutputConfigurationUuid() const
 {
     auto it = m_outputs.constBegin();
     if (m_outputs.size() == 1) {
         // special case: one output
         return (*it)->uuid();
     }
     QCryptographicHash hash(QCryptographicHash::Md5);
     for (; it != m_outputs.constEnd(); ++it) {
         hash.addData((*it)->uuid());
     }
     return hash.result().toHex().left(10);
 }
 
 void DrmBackend::configurationChangeRequested(KWayland::Server::OutputConfigurationInterface *config)
 {
     const auto changes = config->changes();
     for (auto it = changes.begin(); it != changes.end(); it++) {
 
         KWayland::Server::OutputChangeSet *changeset = it.value();
 
         auto drmoutput = findOutput(it.key()->uuid());
         if (drmoutput == nullptr) {
             qCWarning(KWIN_DRM) << "Could NOT find DrmOutput matching " << it.key()->uuid();
             return;
         }
         drmoutput->setChanges(changeset);
     }
     emit screens()->changed();
 }
 
 DrmOutput *DrmBackend::findOutput(quint32 connector)
 {
     auto it = std::find_if(m_outputs.constBegin(), m_outputs.constEnd(), [connector] (DrmOutput *o) {
         return o->m_conn->id() == connector;
     });
     if (it != m_outputs.constEnd()) {
         return *it;
     }
     return nullptr;
 }
 
 DrmOutput *DrmBackend::findOutput(const QByteArray &uuid)
 {
     auto it = std::find_if(m_outputs.constBegin(), m_outputs.constEnd(), [uuid] (DrmOutput *o) {
         return o->m_uuid == uuid;
     });
     if (it != m_outputs.constEnd()) {
         return *it;
     }
     return nullptr;
 }
 
 void DrmBackend::present(DrmBuffer *buffer, DrmOutput *output)
 {
     if (output->present(buffer)) {
         m_pageFlipsPending++;
         if (m_pageFlipsPending == 1 && Compositor::self()) {
             Compositor::self()->aboutToSwapBuffers();
         }
     }
 }
 
 void DrmBackend::initCursor()
 {
     m_cursorEnabled = waylandServer()->seat()->hasPointer();
     connect(waylandServer()->seat(), &KWayland::Server::SeatInterface::hasPointerChanged, this,
         [this] {
             m_cursorEnabled = waylandServer()->seat()->hasPointer();
             if (usesSoftwareCursor()) {
                 return;
             }
             for (auto it = m_outputs.constBegin(); it != m_outputs.constEnd(); ++it) {
                 if (m_cursorEnabled) {
                     (*it)->showCursor(m_cursor[m_cursorIndex]);
                 } else {
                     (*it)->hideCursor();
                 }
             }
         }
     );
     uint64_t capability = 0;
     QSize cursorSize;
     if (drmGetCap(m_fd, DRM_CAP_CURSOR_WIDTH, &capability) == 0) {
         cursorSize.setWidth(capability);
     } else {
         cursorSize.setWidth(64);
     }
     if (drmGetCap(m_fd, DRM_CAP_CURSOR_HEIGHT, &capability) == 0) {
         cursorSize.setHeight(capability);
     } else {
         cursorSize.setHeight(64);
     }
     auto createCursor = [this, cursorSize] (int index) {
         m_cursor[index] = createBuffer(cursorSize);
         if (!m_cursor[index]->map(QImage::Format_ARGB32_Premultiplied)) {
             return false;
         }
         m_cursor[index]->image()->fill(Qt::transparent);
         return true;
     };
     if (!createCursor(0) || !createCursor(1)) {
         setSoftWareCursor(true);
         return;
     }
     // now we have screens and can set cursors, so start tracking
     connect(this, &DrmBackend::cursorChanged, this, &DrmBackend::updateCursor);
     connect(Cursor::self(), &Cursor::posChanged, this, &DrmBackend::moveCursor);
 }
 
 void DrmBackend::setCursor()
 {
     DrmDumbBuffer *c = m_cursor[m_cursorIndex];
     m_cursorIndex = (m_cursorIndex + 1) % 2;
     if (m_cursorEnabled) {
         for (auto it = m_outputs.constBegin(); it != m_outputs.constEnd(); ++it) {
             (*it)->showCursor(c);
         }
     }
     markCursorAsRendered();
 }
 
 void DrmBackend::updateCursor()
 {
     if (usesSoftwareCursor()) {
         return;
     }
     if (isCursorHidden()) {
         return;
     }
     const QImage &cursorImage = softwareCursor();
     if (cursorImage.isNull()) {
         doHideCursor();
         return;
     }
     QImage *c = m_cursor[m_cursorIndex]->image();
     c->fill(Qt::transparent);
     QPainter p;
     p.begin(c);
     p.drawImage(QPoint(0, 0), cursorImage);
     p.end();
 
     setCursor();
     moveCursor();
 }
 
 void DrmBackend::doShowCursor()
 {
     updateCursor();
 }
 
 void DrmBackend::doHideCursor()
 {
     if (!m_cursorEnabled) {
         return;
     }
     for (auto it = m_outputs.constBegin(); it != m_outputs.constEnd(); ++it) {
         (*it)->hideCursor();
     }
 }
 
 void DrmBackend::moveCursor()
 {
     const QPoint p = Cursor::pos() - softwareCursorHotspot();
     if (!m_cursorEnabled || isCursorHidden()) {
         return;
     }
     for (auto it = m_outputs.constBegin(); it != m_outputs.constEnd(); ++it) {
         (*it)->moveCursor(p);
     }
 }
 
 Screens *DrmBackend::createScreens(QObject *parent)
 {
     return new DrmScreens(this, parent);
 }
 
 QPainterBackend *DrmBackend::createQPainterBackend()
 {
     m_deleteBufferAfterPageFlip = false;
     return new DrmQPainterBackend(this);
 }
 
 OpenGLBackend *DrmBackend::createOpenGLBackend()
 {
 #if HAVE_GBM
     m_deleteBufferAfterPageFlip = true;
     return new EglGbmBackend(this);
 #else
     return Platform::createOpenGLBackend();
 #endif
 }
 
 DrmDumbBuffer *DrmBackend::createBuffer(const QSize &size)
 {
     DrmDumbBuffer *b = new DrmDumbBuffer(this, size);
     return b;
 }
 
 #if HAVE_GBM
 DrmSurfaceBuffer *DrmBackend::createBuffer(gbm_surface *surface)
 {
     DrmSurfaceBuffer *b = new DrmSurfaceBuffer(this, surface);
     return b;
 }
 #endif
 
 void DrmBackend::outputDpmsChanged()
 {
     if (m_outputs.isEmpty()) {
         return;
     }
     bool enabled = false;
     for (auto it = m_outputs.constBegin(); it != m_outputs.constEnd(); ++it) {
         enabled = enabled || (*it)->isDpmsEnabled();
     }
     setOutputsEnabled(enabled);
 }
 
 }