ui: Deliver refresh rate via QemuUIInfo

This change adds a new member, refresh_rate to QemuUIInfo in
include/ui/console.h. It represents the refresh rate of the
physical display backend, and it is more appropriate than
GUI update interval as the refresh rate which the emulated device
reports:
- sdl may set GUI update interval shorter than the refresh rate
  of the physical display to respond to user-generated events.
- sdl and vnc aggressively changes GUI update interval, but
  a guests is typically not designed to respond to frequent
  refresh rate changes, or frequent "display mode" changes in
  general. The frequency of refresh rate changes of the physical
  display backend matches better to the guest's expectation.

QemuUIInfo also has other members representing "display mode",
which makes it suitable for refresh rate representation. It has
a throttling of update notifications, and prevents frequent changes
of the display mode.

Signed-off-by: Akihiko Odaki <akihiko.odaki@gmail.com>
Message-Id: <20220226115516.59830-3-akihiko.odaki@gmail.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

hw/display/xenfb.c

@@ -777,16 +777,24 @@ static void xenfb_update(void *opaque)
     xenfb->up_fullscreen = 0;
 }
 
-static void xenfb_update_interval(void *opaque, uint64_t interval)
+static void xenfb_ui_info(void *opaque, uint32_t idx, QemuUIInfo *info)
 {
     struct XenFB *xenfb = opaque;
+    uint32_t refresh_rate;
 
     if (xenfb->feature_update) {
 #ifdef XENFB_TYPE_REFRESH_PERIOD
         if (xenfb_queue_full(xenfb)) {
             return;
         }
-        xenfb_send_refresh_period(xenfb, interval);
+
+        refresh_rate = info->refresh_rate;
+        if (!refresh_rate) {
+            refresh_rate = 75;
+        }
+
+        /* T = 1 / f = 1 [s*Hz] / f = 1000*1000 [ms*mHz] / f */
+        xenfb_send_refresh_period(xenfb, 1000 * 1000 / refresh_rate);
 #endif
     }
 }
@@ -983,5 +991,5 @@ struct XenDevOps xen_framebuffer_ops = {
 static const GraphicHwOps xenfb_ops = {
     .invalidate  = xenfb_invalidate,
     .gfx_update  = xenfb_update,
-    .update_interval = xenfb_update_interval,
+    .ui_info     = xenfb_ui_info,
 };

include/ui/console.h

@@ -139,6 +139,7 @@ typedef struct QemuUIInfo {
     int       yoff;
     uint32_t  width;
     uint32_t  height;
+    uint32_t  refresh_rate;
 } QemuUIInfo;
 
 /* cursor data format is 32bit RGBA */
@@ -431,7 +432,6 @@ typedef struct GraphicHwOps {
     void (*gfx_update)(void *opaque);
     bool gfx_update_async; /* if true, calls graphic_hw_update_done() */
     void (*text_update)(void *opaque, console_ch_t *text);
-    void (*update_interval)(void *opaque, uint64_t interval);
     void (*ui_info)(void *opaque, uint32_t head, QemuUIInfo *info);
     void (*gl_block)(void *opaque, bool block);
 } GraphicHwOps;

include/ui/gtk.h

@@ -155,7 +155,7 @@ extern bool gtk_use_gl_area;
 
 /* ui/gtk.c */
 void gd_update_windowsize(VirtualConsole *vc);
-int gd_monitor_update_interval(GtkWidget *widget);
+void gd_update_monitor_refresh_rate(VirtualConsole *vc, GtkWidget *widget);
 void gd_hw_gl_flushed(void *vc);
 
 /* ui/gtk-egl.c */

ui/console.c

@@ -160,7 +160,6 @@ static void gui_update(void *opaque)
     uint64_t dcl_interval;
     DisplayState *ds = opaque;
     DisplayChangeListener *dcl;
-    QemuConsole *con;
 
     ds->refreshing = true;
     dpy_refresh(ds);
@@ -175,11 +174,6 @@ static void gui_update(void *opaque)
     }
     if (ds->update_interval != interval) {
         ds->update_interval = interval;
-        QTAILQ_FOREACH(con, &consoles, next) {
-            if (con->hw_ops->update_interval) {
-                con->hw_ops->update_interval(con->hw, interval);
-            }
-        }
         trace_console_refresh(interval);
     }
     ds->last_update = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);

ui/gtk-egl.c

@@ -140,8 +140,8 @@ void gd_egl_refresh(DisplayChangeListener *dcl)
 {
     VirtualConsole *vc = container_of(dcl, VirtualConsole, gfx.dcl);
 
-    vc->gfx.dcl.update_interval = gd_monitor_update_interval(
-            vc->window ? vc->window : vc->gfx.drawing_area);
+    gd_update_monitor_refresh_rate(
+            vc, vc->window ? vc->window : vc->gfx.drawing_area);
 
     if (!vc->gfx.esurface) {
         gd_egl_init(vc);

ui/gtk-gl-area.c

@@ -121,8 +121,7 @@ void gd_gl_area_refresh(DisplayChangeListener *dcl)
 {
     VirtualConsole *vc = container_of(dcl, VirtualConsole, gfx.dcl);
 
-    vc->gfx.dcl.update_interval = gd_monitor_update_interval(
-            vc->window ? vc->window : vc->gfx.drawing_area);
+    gd_update_monitor_refresh_rate(vc, vc->window ? vc->window : vc->gfx.drawing_area);
 
     if (!vc->gfx.gls) {
         if (!gtk_widget_get_realized(vc->gfx.drawing_area)) {

ui/gtk.c

@@ -710,11 +710,20 @@ static gboolean gd_window_close(GtkWidget *widget, GdkEvent *event,
     return TRUE;
 }
 
-static void gd_set_ui_info(VirtualConsole *vc, gint width, gint height)
+static void gd_set_ui_refresh_rate(VirtualConsole *vc, int refresh_rate)
 {
     QemuUIInfo info;
 
-    memset(&info, 0, sizeof(info));
+    info = *dpy_get_ui_info(vc->gfx.dcl.con);
+    info.refresh_rate = refresh_rate;
+    dpy_set_ui_info(vc->gfx.dcl.con, &info, true);
+}
+
+static void gd_set_ui_size(VirtualConsole *vc, gint width, gint height)
+{
+    QemuUIInfo info;
+
+    info = *dpy_get_ui_info(vc->gfx.dcl.con);
     info.width = width;
     info.height = height;
     dpy_set_ui_info(vc->gfx.dcl.con, &info, true);
@@ -738,33 +747,32 @@ static void gd_resize_event(GtkGLArea *area,
 {
     VirtualConsole *vc = (void *)opaque;
 
-    gd_set_ui_info(vc, width, height);
+    gd_set_ui_size(vc, width, height);
 }
 
 #endif
 
-/*
- * If available, return the update interval of the monitor in ms,
- * else return 0 (the default update interval).
- */
-int gd_monitor_update_interval(GtkWidget *widget)
+void gd_update_monitor_refresh_rate(VirtualConsole *vc, GtkWidget *widget)
 {
 #ifdef GDK_VERSION_3_22
     GdkWindow *win = gtk_widget_get_window(widget);
+    int refresh_rate;
 
     if (win) {
         GdkDisplay *dpy = gtk_widget_get_display(widget);
         GdkMonitor *monitor = gdk_display_get_monitor_at_window(dpy, win);
-        int refresh_rate = gdk_monitor_get_refresh_rate(monitor); /* [mHz] */
-
-        if (refresh_rate) {
-            /* T = 1 / f = 1 [s*Hz] / f = 1000*1000 [ms*mHz] / f */
-            return MIN(1000 * 1000 / refresh_rate,
-                       GUI_REFRESH_INTERVAL_DEFAULT);
-        }
+        refresh_rate = gdk_monitor_get_refresh_rate(monitor); /* [mHz] */
+    } else {
+        refresh_rate = 0;
     }
+
+    gd_set_ui_refresh_rate(vc, refresh_rate);
+
+    /* T = 1 / f = 1 [s*Hz] / f = 1000*1000 [ms*mHz] / f */
+    vc->gfx.dcl.update_interval = refresh_rate ?
+        MIN(1000 * 1000 / refresh_rate, GUI_REFRESH_INTERVAL_DEFAULT) :
+        GUI_REFRESH_INTERVAL_DEFAULT;
 #endif
-    return 0;
 }
 
 static gboolean gd_draw_event(GtkWidget *widget, cairo_t *cr, void *opaque)
@@ -801,8 +809,7 @@ static gboolean gd_draw_event(GtkWidget *widget, cairo_t *cr, void *opaque)
         return FALSE;
     }
 
-    vc->gfx.dcl.update_interval =
-        gd_monitor_update_interval(vc->window ? vc->window : s->window);
+    gd_update_monitor_refresh_rate(vc, vc->window ? vc->window : s->window);
 
     fbw = surface_width(vc->gfx.ds);
     fbh = surface_height(vc->gfx.ds);
@@ -1691,7 +1698,7 @@ static gboolean gd_configure(GtkWidget *widget,
 {
     VirtualConsole *vc = opaque;
 
-    gd_set_ui_info(vc, cfg->width, cfg->height);
+    gd_set_ui_size(vc, cfg->width, cfg->height);
     return FALSE;
 }