[PATCH 2/2] drm: rcar-du: Don't restart group when enabling plane on Gen3

[Laurent Pinchart]

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+rene...@ideasonboard.com>
---
 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);
 }
 
-- 
Regards,

Laurent Pinchart