drm: qxl: use vblank hooks in struct drm_crtc_funcs

The vblank hooks in struct drm_driver are deprecated and only meant for
legacy drivers.  For modern drivers with DRIVER_MODESET flag, the hooks
in struct drm_crtc_funcs should be used instead.

Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
Cc: Dave Airlie <airlied@redhat.com>
Signed-off-by: Sean Paul <seanpaul@chromium.org>
Link: http://patchwork.freedesktop.org/patch/msgid/1486458995-31018-16-git-send-email-shawnguo@kernel.org
diff --git a/drivers/gpu/drm/qxl/qxl_display.c b/drivers/gpu/drm/qxl/qxl_display.c
index 1094cd3..2ce805a 100644
--- a/drivers/gpu/drm/qxl/qxl_display.c
+++ b/drivers/gpu/drm/qxl/qxl_display.c
@@ -548,6 +548,19 @@ static int qxl_crtc_cursor_move(struct drm_crtc *crtc,
 	return 0;
 }
 
+static u32 qxl_noop_get_vblank_counter(struct drm_crtc *crtc)
+{
+	return 0;
+}
+
+static int qxl_noop_enable_vblank(struct drm_crtc *crtc)
+{
+	return 0;
+}
+
+static void qxl_noop_disable_vblank(struct drm_crtc *crtc)
+{
+}
 
 static const struct drm_crtc_funcs qxl_crtc_funcs = {
 	.cursor_set2 = qxl_crtc_cursor_set2,
@@ -555,6 +568,9 @@ static const struct drm_crtc_funcs qxl_crtc_funcs = {
 	.set_config = drm_crtc_helper_set_config,
 	.destroy = qxl_crtc_destroy,
 	.page_flip = qxl_crtc_page_flip,
+	.get_vblank_counter = qxl_noop_get_vblank_counter,
+	.enable_vblank = qxl_noop_enable_vblank,
+	.disable_vblank = qxl_noop_disable_vblank,
 };
 
 void qxl_user_framebuffer_destroy(struct drm_framebuffer *fb)