If we have more than one CRTCs in a group pre-associate planes 0-3 with
CRTC 0 and planes 4-7 with CRTC 1 to minimize flicker occurring when the
association is changed. The pre-association could be controlled by a
module parameter if needed.
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas at ideasonboard.com>
---
drivers/gpu/drm/rcar-du/rcar_du_crtc.c | 3 ---
drivers/gpu/drm/rcar-du/rcar_du_kms.c | 7 ++++---
2 files changed, 4 insertions(+), 6 deletions(-)
diff --git a/drivers/gpu/drm/rcar-du/rcar_du_crtc.c
b/drivers/gpu/drm/rcar-du/rcar_du_crtc.c
index 620a2c51185c..e6a32c4e4040 100644
--- a/drivers/gpu/drm/rcar-du/rcar_du_crtc.c
+++ b/drivers/gpu/drm/rcar-du/rcar_du_crtc.c
@@ -257,9 +257,6 @@ static void rcar_du_crtc_update_planes(struct rcar_du_crtc
*rcrtc)
* resulting in visible flicker. To mitigate the issue only update the
* association if needed by enabled planes. Planes being disabled will
* keep their current association.
- *
- * To mitigate the issue further we could pre-associate planes with
- * CRTCs, either with a fixed 4/4 split, or through a module parameter.
*/
mutex_lock(&rcrtc->group->lock);
diff --git a/drivers/gpu/drm/rcar-du/rcar_du_kms.c
b/drivers/gpu/drm/rcar-du/rcar_du_kms.c
index fec5f4d794da..20859aae882e 100644
--- a/drivers/gpu/drm/rcar-du/rcar_du_kms.c
+++ b/drivers/gpu/drm/rcar-du/rcar_du_kms.c
@@ -765,10 +765,11 @@ int rcar_du_modeset_init(struct rcar_du_device *rcdu)
rgrp->index = i;
rgrp->num_crtcs = min(rcdu->num_crtcs - 2 * i, 2U);
- /* Pre-associate all hardware planes with the first CRTC in the
- * group.
+ /* If we have more than one CRTCs in this group pre-associate
+ * planes 0-3 with CRTC 0 and planes 4-7 with CRTC 1 to minimize
+ * flicker occurring when the association is changed.
*/
- rgrp->dptsr_planes = 0;
+ rgrp->dptsr_planes = rgrp->num_crtcs > 1 ? 0xf0 : 0;
ret = rcar_du_planes_init(rgrp);
if (ret < 0)
--
2.0.5
