eglfs: kms: Fix hw cursor with multiple screens

We used to have the assumption that moving the cursor to an out of
range position is valid and will result in a hidden cursor.

This is apparently not the case. For example, on an RPi4 with Mesa
V3D we get lots of funny artifacts after doing drmModeMoveCursor()
to invalid positions.

To remedy this, start hiding the cursor correctly when the position
is clearly out of the screen's bounds.

Task-number: QTBUG-79924
Change-Id: I3ef7ad0ce928546399443f21452f0b6deadf8036
Reviewed-by: Andy Nichols <andy.nichols@qt.io>

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

@@ -214,7 +214,8 @@ void QEglFSKmsGbmCursor::changeCursor(QCursor *windowCursor, QWindow *window)
 
     Q_FOREACH (QPlatformScreen *screen, m_screen->virtualSiblings()) {
         QEglFSKmsScreen *kmsScreen = static_cast<QEglFSKmsScreen *>(screen);
-
+        if (kmsScreen->isCursorOutOfRange())
+            continue;
         int status = drmModeSetCursor(kmsScreen->device()->fd(), kmsScreen->output().crtc_id, handle,
                                       m_cursorSize.width(), m_cursorSize.height());
         if (status != 0)
@@ -232,17 +233,36 @@ void QEglFSKmsGbmCursor::setPos(const QPoint &pos)
 {
     Q_FOREACH (QPlatformScreen *screen, m_screen->virtualSiblings()) {
         QEglFSKmsScreen *kmsScreen = static_cast<QEglFSKmsScreen *>(screen);
-        QPoint origin = kmsScreen->geometry().topLeft();
-        QPoint localPos = pos - origin;
-        QPoint adjustedPos = localPos - m_cursorImage.hotspot();
+        const QRect screenGeom = kmsScreen->geometry();
+        const QPoint origin = screenGeom.topLeft();
+        const QPoint localPos = pos - origin;
+        const QPoint adjustedLocalPos = localPos - m_cursorImage.hotspot();
 
-        int ret = drmModeMoveCursor(kmsScreen->device()->fd(), kmsScreen->output().crtc_id, adjustedPos.x(), adjustedPos.y());
-        if (ret == 0)
-            m_pos = pos;
-        else
-            qWarning("Failed to move cursor on screen %s: %d", kmsScreen->name().toLatin1().constData(), ret);
+        if (localPos.x() < 0 || localPos.y() < 0
+            || localPos.x() >= screenGeom.width() || localPos.y() >= screenGeom.height())
+        {
+            if (!kmsScreen->isCursorOutOfRange()) {
+                kmsScreen->setCursorOutOfRange(true);
+                drmModeSetCursor(kmsScreen->device()->fd(), kmsScreen->output().crtc_id, 0, 0, 0);
+            }
+        } else {
+            int ret;
+            if (kmsScreen->isCursorOutOfRange()) {
+                kmsScreen->setCursorOutOfRange(false);
+                uint32_t handle = gbm_bo_get_handle(m_bo).u32;
+                ret = drmModeSetCursor(kmsScreen->device()->fd(), kmsScreen->output().crtc_id,
+                                       handle, m_cursorSize.width(), m_cursorSize.height());
+            } else {
+                ret = drmModeMoveCursor(kmsScreen->device()->fd(), kmsScreen->output().crtc_id,
+                                        adjustedLocalPos.x(), adjustedLocalPos.y());
+            }
+            if (ret == 0)
+                m_pos = pos;
+            else
+                qWarning("Failed to move cursor on screen %s: %d", kmsScreen->name().toLatin1().constData(), ret);
 
-        kmsScreen->handleCursorMove(pos);
+            kmsScreen->handleCursorMove(pos);
+        }
     }
 }
 

src/plugins/platforms/eglfs/deviceintegration/eglfs_kms/qeglfskmsgbmcursor.h

@@ -85,6 +85,8 @@ public:
 
     void updateMouseStatus();
 
+    void reevaluateVisibilityForScreens() { setPos(pos()); }
+
 private:
     void initCursorAtlas();
 

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

@@ -155,4 +155,14 @@ void QEglFSKmsGbmDevice::registerScreenCloning(QPlatformScreen *screen,
     gbmScreen->initCloning(screenThisScreenClones, screensCloningThisScreen);
 }
 
+void QEglFSKmsGbmDevice::registerScreen(QPlatformScreen *screen,
+                                        bool isPrimary,
+                                        const QPoint &virtualPos,
+                                        const QList<QPlatformScreen *> &virtualSiblings)
+{
+    QEglFSKmsDevice::registerScreen(screen, isPrimary, virtualPos, virtualSiblings);
+    if (screenConfig()->hwCursor() && m_globalCursor)
+        m_globalCursor->reevaluateVisibilityForScreens();
+}
+
 QT_END_NAMESPACE

src/plugins/platforms/eglfs/deviceintegration/eglfs_kms/qeglfskmsgbmdevice.h

@@ -70,6 +70,10 @@ public:
     void registerScreenCloning(QPlatformScreen *screen,
                                QPlatformScreen *screenThisScreenClones,
                                const QVector<QPlatformScreen *> &screensCloningThisScreen) override;
+    void registerScreen(QPlatformScreen *screen,
+                        bool isPrimary,
+                        const QPoint &virtualPos,
+                        const QList<QPlatformScreen *> &virtualSiblings) override;
 
 private:
     Q_DISABLE_COPY(QEglFSKmsGbmDevice)

src/plugins/platforms/eglfs/deviceintegration/eglfs_kms_support/qeglfskmsscreen.cpp

@@ -72,6 +72,7 @@ QEglFSKmsScreen::QEglFSKmsScreen(QKmsDevice *device, const QKmsOutput &output, b
     : QEglFSScreen(static_cast<QEglFSIntegration *>(QGuiApplicationPrivate::platformIntegration())->display())
     , m_device(device)
     , m_output(output)
+    , m_cursorOutOfRange(false)
     , m_powerState(PowerStateOn)
     , m_interruptHandler(new QEglFSKmsInterruptHandler(this))
     , m_headless(headless)

src/plugins/platforms/eglfs/deviceintegration/eglfs_kms_support/qeglfskmsscreen.h

@@ -99,12 +99,16 @@ public:
     QPlatformScreen::PowerState powerState() const override;
     void setPowerState(QPlatformScreen::PowerState state) override;
 
+    bool isCursorOutOfRange() const { return m_cursorOutOfRange; }
+    void setCursorOutOfRange(bool b) { m_cursorOutOfRange = b; }
+
 protected:
     QKmsDevice *m_device;
 
     QKmsOutput m_output;
     QEdidParser m_edid;
     QPoint m_pos;
+    bool m_cursorOutOfRange;
 
     QList<QPlatformScreen *> m_siblings;