eglfs: Report the QScreen refresh rate from eglfs

For KMS we can always know the correct rate so report it from the backend's custom
screen implementation.

For the rest, query from the framebuffer. If the fb driver publishes the timings then
we can calculate the vertical refresh rate from them. If not, default to 60.

Task-number: QTBUG-44971
Change-Id: I854a34e7c0d652790cc2ac967715828ec76f5733
Reviewed-by: Andy Nichols <andy.nichols@theqtcompany.com>

src/platformsupport/eglconvenience/qeglconvenience.cpp

@@ -576,6 +576,33 @@ int q_screenDepthFromFb(int framebufferDevice)
     return depth;
 }
 
+qreal q_refreshRateFromFb(int framebufferDevice)
+{
+    static qreal rate = 0;
+
+#ifdef Q_OS_LINUX
+    if (rate == 0) {
+        if (framebufferDevice != -1) {
+            struct fb_var_screeninfo vinfo;
+            if (ioctl(framebufferDevice, FBIOGET_VSCREENINFO, &vinfo) != -1) {
+                const quint64 quot = quint64(vinfo.left_margin + vinfo.right_margin + vinfo.xres + vinfo.hsync_len)
+                    * quint64(vinfo.upper_margin + vinfo.lower_margin + vinfo.yres + vinfo.vsync_len)
+                    * vinfo.pixclock;
+                if (quot)
+                    rate = 1000000000000LLU / quot;
+            } else {
+                qWarning("eglconvenience: Could not query screen info");
+            }
+        }
+    }
+#endif
+
+    if (rate == 0)
+        rate = 60;
+
+    return rate;
+}
+
 #endif // Q_OS_UNIX
 
 QT_END_NAMESPACE

src/platformsupport/eglconvenience/qeglconvenience_p.h

@@ -63,6 +63,7 @@ void q_printEglConfig(EGLDisplay display, EGLConfig config);
 QSizeF q_physicalScreenSizeFromFb(int framebufferDevice, const QSize &screenSize = QSize());
 QSize q_screenSizeFromFb(int framebufferDevice);
 int q_screenDepthFromFb(int framebufferDevice);
+qreal q_refreshRateFromFb(int framebufferDevice);
 #endif
 
 class QEglConfigChooser

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

@@ -303,4 +303,10 @@ void QEglFSKmsScreen::restoreMode()
     }
 }
 
+qreal QEglFSKmsScreen::refreshRate() const
+{
+    quint32 refresh = m_output.modes[m_output.mode].vrefresh;
+    return refresh > 0 ? refresh : 60;
+}
+
 QT_END_NAMESPACE

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

@@ -83,6 +83,8 @@ public:
 
     QPlatformCursor *cursor() const Q_DECL_OVERRIDE;
 
+    qreal refreshRate() const Q_DECL_OVERRIDE;
+
     QEglFSKmsDevice *device() const { return m_device; }
 
     gbm_surface *surface() const { return m_gbm_surface; }

src/plugins/platforms/eglfs/qeglfsdeviceintegration.cpp

@@ -225,6 +225,11 @@ QImage::Format QEGLDeviceIntegration::screenFormat() const
     return screenDepth() == 16 ? QImage::Format_RGB16 : QImage::Format_RGB32;
 }
 
+qreal QEGLDeviceIntegration::refreshRate() const
+{
+    return q_refreshRateFromFb(framebuffer);
+}
+
 QSurfaceFormat QEGLDeviceIntegration::surfaceFormatFor(const QSurfaceFormat &inputFormat) const
 {
     QSurfaceFormat format = inputFormat;

src/plugins/platforms/eglfs/qeglfsdeviceintegration.h

@@ -77,6 +77,7 @@ public:
     virtual Qt::ScreenOrientation orientation() const;
     virtual int screenDepth() const;
     virtual QImage::Format screenFormat() const;
+    virtual qreal refreshRate() const;
     virtual QSurfaceFormat surfaceFormatFor(const QSurfaceFormat &inputFormat) const;
     virtual EGLNativeWindowType createNativeWindow(QPlatformWindow *platformWindow,
                                                    const QSize &size,

src/plugins/platforms/eglfs/qeglfsscreen.cpp

@@ -93,6 +93,11 @@ QPlatformCursor *QEglFSScreen::cursor() const
     return m_cursor;
 }
 
+qreal QEglFSScreen::refreshRate() const
+{
+    return qt_egl_device_integration()->refreshRate();
+}
+
 void QEglFSScreen::setPrimarySurface(EGLSurface surface)
 {
     m_surface = surface;

src/plugins/platforms/eglfs/qeglfsscreen.h

@@ -60,6 +60,8 @@ public:
 
     QPlatformCursor *cursor() const Q_DECL_OVERRIDE;
 
+    qreal refreshRate() const Q_DECL_OVERRIDE;
+
     EGLSurface primarySurface() const { return m_surface; }
 
 protected: