modesetting: Call glamor_finish from drmmode_crtc_set_mode

This makes sure any pending drawing to a new scanout buffer will be
visible from the start.

This makes the finish call in drmmode_copy_fb superfluous, so remove it.
Reviewed-by: Adam Jackson <ajax@redhat.com>

hw/xfree86/drivers/modesetting/drmmode_display.c

@@ -755,6 +755,7 @@ drmmode_crtc_set_mode(xf86CrtcPtr crtc, Bool test_only)
     xf86CrtcConfigPtr xf86_config = XF86_CRTC_CONFIG_PTR(crtc->scrn);
     drmmode_crtc_private_ptr drmmode_crtc = crtc->driver_private;
     drmmode_ptr drmmode = drmmode_crtc->drmmode;
+    ScreenPtr screen = crtc->scrn->pScreen;
     drmModeModeInfo kmode;
     int output_count = 0;
     uint32_t *output_ids = NULL;
@@ -765,6 +766,12 @@ drmmode_crtc_set_mode(xf86CrtcPtr crtc, Bool test_only)
     if (!drmmode_crtc_get_fb_id(crtc, &fb_id, &x, &y))
         return 1;
 
+#ifdef GLAMOR_HAS_GBM
+    /* Make sure any pending drawing will be visible in a new scanout buffer */
+    if (drmmode->glamor)
+        glamor_finish(screen);
+#endif
+
     if (ms->atomic_modeset) {
         drmModeAtomicReq *req = drmModeAtomicAlloc();
         Bool active;
@@ -1419,7 +1426,6 @@ drmmode_copy_fb(ScrnInfoPtr pScrn, drmmode_ptr drmmode)
 #ifdef GLAMOR_HAS_GBM
     xf86CrtcConfigPtr xf86_config = XF86_CRTC_CONFIG_PTR(pScrn);
     ScreenPtr pScreen = xf86ScrnToScreen(pScrn);
-    modesettingPtr ms = modesettingPTR(pScrn);
     PixmapPtr src, dst;
     int fbcon_id = 0;
     GCPtr gc;
@@ -1457,8 +1463,6 @@ drmmode_copy_fb(ScrnInfoPtr pScrn, drmmode_ptr drmmode)
 
     FreeScratchGC(gc);
 
-    glamor_finish(pScreen);
-
     pScreen->canDoBGNoneRoot = TRUE;
 
     if (drmmode->fbcon_pixmap)