drm/sun4i: backend: Use runtime_pm variant of atomic_commit_tail

During a hardware commit, the commit bit in the backend will only be
cleared if the TCON is enabled. Use the runtime_pm variant of the
atomic_commit_tail hook that makes sure that the CRTC, our TCON, is enabled
when we perform an atomic_commit.

Reviewed-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Link: https://patchwork.freedesktop.org/patch/msgid/bde95faff2078f63e9af99c3abee5360b9050fd1.1516613040.git-series.maxime.ripard@free-electrons.com

drivers/gpu/drm/sun4i/sun4i_framebuffer.c

@@ -10,6 +10,7 @@
  * the License, or (at your option) any later version.
  */
 
+#include <drm/drm_atomic.h>
 #include <drm/drm_atomic_helper.h>
 #include <drm/drm_fb_helper.h>
 #include <drm/drm_fb_cma_helper.h>
@@ -26,6 +27,10 @@ static const struct drm_mode_config_funcs sun4i_de_mode_config_funcs = {
 	.fb_create		= drm_gem_fb_create,
 };
 
+static struct drm_mode_config_helper_funcs sun4i_de_mode_config_helpers = {
+	.atomic_commit_tail	= drm_atomic_helper_commit_tail_rpm,
+};
+
 int sun4i_framebuffer_init(struct drm_device *drm)
 {
 	drm_mode_config_reset(drm);
@@ -34,6 +39,7 @@ int sun4i_framebuffer_init(struct drm_device *drm)
 	drm->mode_config.max_height = 8192;
 
 	drm->mode_config.funcs = &sun4i_de_mode_config_funcs;
+	drm->mode_config.helper_private = &sun4i_de_mode_config_helpers;
 
 	return drm_fb_cma_fbdev_init(drm, 32, 0);
 }