eglfs/kms: Add DRM atomic ModeSetting

This patch will allow to set the video mode with DRM atomic API when available.

Using Atomic ModeSetting will allow further to enable framebuffer upscaling which is
something not possible with DRM legacy API or at least not supported on all devices
in a reliable way.

Change-Id: Ie340585cf4cbf5d65555c9a7c547dcbadb327fc0
Reviewed-by: Laszlo Agocs <laszlo.agocs@qt.io>

src/platformsupport/kmsconvenience/qkmsdevice.cpp

@@ -386,6 +386,16 @@ QPlatformScreen *QKmsDevice::createScreenForConnector(drmModeResPtr resources,
     output.drm_format = drmFormat;
     output.clone_source = cloneSource;
 
+#if QT_CONFIG(drm_atomic)
+    if (drmModeCreatePropertyBlob(m_dri_fd, &modes[selected_mode], sizeof(drmModeModeInfo),
+                                  &output.mode_blob_id) != 0) {
+        qCDebug(qLcKmsDebug) << "Failed to create mode blob for mode" << selected_mode;
+    }
+
+    parseConnectorProperties(output.connector_id, &output);
+    parseCrtcProperties(output.crtc_id, &output);
+#endif
+
     QString planeListStr;
     for (const QKmsPlane &plane : qAsConst(m_planes)) {
         if (plane.possibleCrtcs & (1 << output.crtc_index)) {
@@ -817,7 +827,7 @@ bool QKmsDevice::atomicCommit(void *user_data)
 {
     if (m_atomic_request) {
         int ret = drmModeAtomicCommit(m_dri_fd, m_atomic_request,
-                          DRM_MODE_ATOMIC_NONBLOCK | DRM_MODE_PAGE_FLIP_EVENT, user_data);
+                          DRM_MODE_ATOMIC_NONBLOCK | DRM_MODE_PAGE_FLIP_EVENT | DRM_MODE_ATOMIC_ALLOW_MODESET, user_data);
 
         if (ret) {
            qWarning("Failed to commit atomic request (code=%d)", ret);
@@ -842,6 +852,42 @@ void QKmsDevice::atomicReset()
 }
 #endif
 
+void QKmsDevice::parseConnectorProperties(uint32_t connectorId, QKmsOutput *output)
+{
+    drmModeObjectPropertiesPtr objProps = drmModeObjectGetProperties(m_dri_fd, connectorId, DRM_MODE_OBJECT_CONNECTOR);
+    if (!objProps) {
+        qCDebug(qLcKmsDebug, "Failed to query connector %d object properties", connectorId);
+        return;
+    }
+
+    enumerateProperties(objProps, [output](drmModePropertyPtr prop, quint64 value) {
+        Q_UNUSED(value);
+        if (!strcasecmp(prop->name, "crtc_id"))
+            output->crtcIdPropertyId = prop->prop_id;
+    });
+
+    drmModeFreeObjectProperties(objProps);
+}
+
+void QKmsDevice::parseCrtcProperties(uint32_t crtcId, QKmsOutput *output)
+{
+    drmModeObjectPropertiesPtr objProps = drmModeObjectGetProperties(m_dri_fd, crtcId, DRM_MODE_OBJECT_CRTC);
+    if (!objProps) {
+        qCDebug(qLcKmsDebug, "Failed to query crtc %d object properties", crtcId);
+        return;
+    }
+
+    enumerateProperties(objProps, [output](drmModePropertyPtr prop, quint64 value) {
+        Q_UNUSED(value)
+        if (!strcasecmp(prop->name, "mode_id"))
+            output->modeIdPropertyId = prop->prop_id;
+        else if (!strcasecmp(prop->name, "active"))
+            output->activePropertyId = prop->prop_id;
+    });
+
+    drmModeFreeObjectProperties(objProps);
+}
+
 QKmsScreenConfig *QKmsDevice::screenConfig() const
 {
     return m_screenConfig;

src/platformsupport/kmsconvenience/qkmsdevice_p.h

@@ -195,6 +195,11 @@ struct QKmsOutput
     QString clone_source;
     QVector<QKmsPlane> available_planes;
     struct QKmsPlane *eglfs_plane = nullptr;
+    uint32_t crtcIdPropertyId = 0;
+    uint32_t modeIdPropertyId = 0;
+    uint32_t activePropertyId = 0;
+
+    uint32_t mode_blob_id = 0;
 
     void restoreMode(QKmsDevice *device);
     void cleanup(QKmsDevice *device);
@@ -255,6 +260,8 @@ protected:
     typedef std::function<void(drmModePropertyPtr, quint64)> PropCallback;
     void enumerateProperties(drmModeObjectPropertiesPtr objProps, PropCallback callback);
     void discoverPlanes();
+    void parseConnectorProperties(uint32_t connectorId, QKmsOutput *output);
+    void parseCrtcProperties(uint32_t crtcId, QKmsOutput *output);
 
     QKmsScreenConfig *m_screenConfig;
     QString m_path;

src/plugins/platforms/eglfs/deviceintegration/eglfs_kms/qeglfskmsgbmscreen.cpp

@@ -211,17 +211,29 @@ void QEglFSKmsGbmScreen::ensureModeSet(uint32_t fb)
 
         if (doModeSet) {
             qCDebug(qLcEglfsKmsDebug, "Setting mode for screen %s", qPrintable(name()));
-            int ret = drmModeSetCrtc(fd,
-                                     op.crtc_id,
-                                     fb,
-                                     0, 0,
-                                     &op.connector_id, 1,
-                                     &op.modes[op.mode]);
 
-            if (ret == 0)
-                setPowerState(PowerStateOn);
-            else
-                qErrnoWarning(errno, "Could not set DRM mode for screen %s", qPrintable(name()));
+            if (device()->hasAtomicSupport()) {
+#if QT_CONFIG(drm_atomic)
+                drmModeAtomicReq *request = device()->atomic_request();
+                if (request) {
+                    drmModeAtomicAddProperty(request, op.connector_id, op.crtcIdPropertyId, op.crtc_id);
+                    drmModeAtomicAddProperty(request, op.crtc_id, op.modeIdPropertyId, op.mode_blob_id);
+                    drmModeAtomicAddProperty(request, op.crtc_id, op.activePropertyId, 1);
+                }
+#endif
+            } else {
+                int ret = drmModeSetCrtc(fd,
+                                         op.crtc_id,
+                                         fb,
+                                         0, 0,
+                                         &op.connector_id, 1,
+                                         &op.modes[op.mode]);
+
+                if (ret == 0)
+                    setPowerState(PowerStateOn);
+                else
+                    qErrnoWarning(errno, "Could not set DRM mode for screen %s", qPrintable(name()));
+            }
         }
     }
 }