From 104e2d2df32f5b38edad79d91d120aacfe49eac1 Mon Sep 17 00:00:00 2001
From: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Date: Mon, 21 Feb 2022 18:54:41 +0200
Subject: drm: rcar-du: Don't restart group when enabling plane on Gen3
Git-commit: 8ba3c7bd4dca7ac358e834eabf840012d9564356
Patch-mainline: v5.18-rc1
References: jsc#PED-1166 jsc#PED-1168 jsc#PED-1170 jsc#PED-1218 jsc#PED-1220 jsc#PED-1222 jsc#PED-1223 jsc#PED-1225

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>
Acked-by: Patrik Jakobsson <pjakobsson@suse.de>
---
 drivers/gpu/drm/rcar-du/rcar_du_plane.c | 6 ++++++
 drivers/gpu/drm/rcar-du/rcar_du_vsp.c   | 9 ---------
 2 files changed, 6 insertions(+), 9 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;
 		}
 	}
 }
diff --git a/drivers/gpu/drm/rcar-du/rcar_du_vsp.c b/drivers/gpu/drm/rcar-du/rcar_du_vsp.c
index b7fc5b069cbc..32530d698e75 100644
--- a/drivers/gpu/drm/rcar-du/rcar_du_vsp.c
+++ b/drivers/gpu/drm/rcar-du/rcar_du_vsp.c
@@ -84,15 +84,6 @@ void rcar_du_vsp_enable(struct rcar_du_crtc *crtc)
 
 	__rcar_du_plane_setup(crtc->group, &state);
 
-	/*
-	 * Ensure that the plane source configuration takes effect by requesting
-	 * a restart of the group. See rcar_du_plane_atomic_update() for a more
-	 * detailed explanation.
-	 *
-	 * TODO: Check whether this is still needed on Gen3.
-	 */
-	crtc->group->need_restart = true;
-
 	vsp1_du_setup_lif(crtc->vsp->vsp, crtc->vsp_pipe, &cfg);
 }
 
-- 
2.38.1