drm/rockchip: Add implicit fencing support for planes

Render like lima will attach a fence to the framebuffer dma_buf,
so the display driver should wait for it to finish before showing
the framebufferto prevent tearing.

Generally tested on rk3188, rk3288, rk3328 and rk3399 and
together with an actual lima-based kmscube on rk3188 and rk3328.

Suggested-by: Qiang Yu <yuq825@gmail.com>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Reviewed-by: Neil Armstrong <narmstrong@baylibre.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20181130102449.6430-1-heiko@sntech.de

drivers/gpu/drm/rockchip/rockchip_drm_vop.c

@@ -18,6 +18,7 @@
 #include <drm/drm_crtc.h>
 #include <drm/drm_crtc_helper.h>
 #include <drm/drm_flip_work.h>
+#include <drm/drm_gem_framebuffer_helper.h>
 #include <drm/drm_plane_helper.h>
 #ifdef CONFIG_DRM_ANALOGIX_DP
 #include <drm/bridge/analogix_dp.h>
@@ -823,6 +824,7 @@ static const struct drm_plane_helper_funcs plane_helper_funcs = {
 	.atomic_check = vop_plane_atomic_check,
 	.atomic_update = vop_plane_atomic_update,
 	.atomic_disable = vop_plane_atomic_disable,
+	.prepare_fb = drm_gem_fb_prepare_fb,
 };
 
 static const struct drm_plane_funcs vop_plane_funcs = {