drm/exynos: Let core take care of normalizing the zpos

Instead of re-implementing the drm_atomic_helper_check() locally with just
adding drm_atomic_normalize_zpos() into it, set the
drm_mode_config->normalize_zpos.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
CC: Inki Dae <inki.dae@samsung.com>
CC: Joonyoung Shim <jy0922.shim@samsung.com>
CC: Seung-Woo Kim <sw0312.kim@samsung.com>
CC: Kyungmin Park <kyungmin.park@samsung.com>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Acked-by: Inki Dae <inki.dae@samsung.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180321102029.15248-3-peter.ujfalusi@ti.com

drivers/gpu/drm/exynos/exynos_drm_drv.c

@@ -37,26 +37,6 @@
 #define DRIVER_MAJOR	1
 #define DRIVER_MINOR	0
 
-int exynos_atomic_check(struct drm_device *dev,
-			struct drm_atomic_state *state)
-{
-	int ret;
-
-	ret = drm_atomic_helper_check_modeset(dev, state);
-	if (ret)
-		return ret;
-
-	ret = drm_atomic_normalize_zpos(dev, state);
-	if (ret)
-		return ret;
-
-	ret = drm_atomic_helper_check_planes(dev, state);
-	if (ret)
-		return ret;
-
-	return ret;
-}
-
 static int exynos_drm_open(struct drm_device *dev, struct drm_file *file)
 {
 	struct drm_exynos_file_private *file_priv;

drivers/gpu/drm/exynos/exynos_drm_drv.h

@@ -275,7 +275,6 @@ static inline int exynos_dpi_bind(struct drm_device *dev,
 
 int exynos_atomic_commit(struct drm_device *dev, struct drm_atomic_state *state,
 			 bool nonblock);
-int exynos_atomic_check(struct drm_device *dev, struct drm_atomic_state *state);
 
 
 extern struct platform_driver fimd_driver;

drivers/gpu/drm/exynos/exynos_drm_fb.c

@@ -206,7 +206,7 @@ static struct drm_mode_config_helper_funcs exynos_drm_mode_config_helpers = {
 static const struct drm_mode_config_funcs exynos_drm_mode_config_funcs = {
 	.fb_create = exynos_user_fb_create,
 	.output_poll_changed = drm_fb_helper_output_poll_changed,
-	.atomic_check = exynos_atomic_check,
+	.atomic_check = drm_atomic_helper_check,
 	.atomic_commit = drm_atomic_helper_commit,
 };
 
@@ -227,4 +227,6 @@ void exynos_drm_mode_config_init(struct drm_device *dev)
 	dev->mode_config.helper_private = &exynos_drm_mode_config_helpers;
 
 	dev->mode_config.allow_fb_modifiers = true;
+
+	dev->mode_config.normalize_zpos = true;
 }