drm: rcar-du: Don't restart group when enabling plane on Gen3

On Gen3 hardware enabling a VSP plane doesn't change any register that
requires DRES to take effect. Avoid a group restart in that case.

Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/drivers/gpu/drm/rcar-du/rcar_du_plane.c b/drivers/gpu/drm/rcar-du/rcar_du_plane.c
index 9b058d6cb032..22aeeb1cc1fb 100644
--- a/drivers/gpu/drm/rcar-du/rcar_du_plane.c
+++ b/drivers/gpu/drm/rcar-du/rcar_du_plane.c
@@ -560,6 +560,12 @@ void __rcar_du_plane_setup(struct rcar_du_group *rgrp,
 		if (rcdu->vspd1_sink != vspd1_sink) {
 			rcdu->vspd1_sink = vspd1_sink;
 			rcar_du_set_dpad0_vsp1_routing(rcdu);
+
+			/*
+			 * Changes to the VSP1 sink take effect on DRES and thus
+			 * need a restart of the group.
+			 */
+			rgrp->need_restart = true;
 		}
 	}
 }