drm/exynos: add atomic_check callback to exynos_crtc

Some CRTCs needs mode validation, this patch adds neccessary
callback to Exynos DRM framework. It is called from DRM core
via atomic_check helper for drm_crtc.

Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>
Signed-off-by: Inki Dae <inki.dae@samsung.com>
diff --git a/drivers/gpu/drm/exynos/exynos_drm_crtc.c b/drivers/gpu/drm/exynos/exynos_drm_crtc.c
index 50dec0d..b3ba27f 100644
--- a/drivers/gpu/drm/exynos/exynos_drm_crtc.c
+++ b/drivers/gpu/drm/exynos/exynos_drm_crtc.c
@@ -50,6 +50,17 @@
 		exynos_crtc->ops->commit(exynos_crtc);
 }
 
+static int exynos_crtc_atomic_check(struct drm_crtc *crtc,
+				     struct drm_crtc_state *state)
+{
+	struct exynos_drm_crtc *exynos_crtc = to_exynos_crtc(crtc);
+
+	if (exynos_crtc->ops->atomic_check)
+		return exynos_crtc->ops->atomic_check(exynos_crtc, state);
+
+	return 0;
+}
+
 static void exynos_crtc_atomic_begin(struct drm_crtc *crtc,
 				     struct drm_crtc_state *old_crtc_state)
 {
@@ -86,6 +97,7 @@
 	.enable		= exynos_drm_crtc_enable,
 	.disable	= exynos_drm_crtc_disable,
 	.mode_set_nofb	= exynos_drm_crtc_mode_set_nofb,
+	.atomic_check	= exynos_crtc_atomic_check,
 	.atomic_begin	= exynos_crtc_atomic_begin,
 	.atomic_flush	= exynos_crtc_atomic_flush,
 };