From: LUU HOAI <hoai.luu.ub@...>

commit b7aaa61726cbc7b941007af14a9f991a828c67e4 upstream.

As per R-Car-Gen3_Common_OPC_Customer_Notifications_V30.1.pdf,
unexpected image output(such as incorrect colors or planes being
invisible) can happen on the below conditions, as PnALPHAR register
is not initialized by reset.

When alpha blending (PpMRm.PpSPIM=0b101) is performed and:
•two Planes are enabled on any DUn (n=0,1,2,3)
oDSPRn= 0x0000 0031 or 0x0000 0013
•or DU0 and DU1 is used for display at the same time
oDSPR0= 0x0000 0001 and DSPR1= 0x0000 0003
oDSPR0= 0x0000 0003 and DSPR1= 0x0000 0001
•or DU2 and DU3(H3 Only) is used for display at the same time
oDSPR2= 0x0000 0001 and DSPR3= 0x0000 0003
oDSPR2= 0x0000 0003 and DSPR3= 0x0000 0001

This patch set PnALPHAR register to 0 to avoid this issue.

Signed-off-by: LUU HOAI <hoai.luu.ub@...>
Signed-off-by: Biju Das <biju.das.jz@...>
Reviewed-by: Laurent Pinchart <laurent.pinchart@...>
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@...>
Signed-off-by: Biju Das <biju.das.jz@...>
---
drivers/gpu/drm/rcar-du/rcar_du_plane.c | 12 ++++++++++++
1 file changed, 12 insertions(+)

diff --git a/drivers/gpu/drm/rcar-du/rcar_du_plane.c b/drivers/gpu/drm/rcar-du/rcar_du_plane.c
index c20f7ed48c8d..366b4de7f055 100644
--- a/drivers/gpu/drm/rcar-du/rcar_du_plane.c
+++ b/drivers/gpu/drm/rcar-du/rcar_du_plane.c
@@ -514,6 +514,18 @@ static void rcar_du_plane_setup_format_gen3(struct rcar_du_group *rgrp,

rcar_du_plane_write(rgrp, index, PnDDCR4,
state->format->edf | PnDDCR4_CODE);
+
+ /*
+ * On Gen3, some DU channels have two planes, each being wired to a
+ * separate VSPD instance. The DU can then blend two planes. While
+ * this feature isn't used by the driver, issues related to alpha
+ * blending (such as incorrect colors or planes being invisible) may
+ * still occur if the PnALPHAR register has a stale value. Set the
+ * register to 0 to avoid this.
+ */
+
+ /* TODO: Check if alpha-blending should be disabled in PnMR. */
+ rcar_du_plane_write(rgrp, index, PnALPHAR, 0);
}

static void rcar_du_plane_setup_format(struct rcar_du_group *rgrp,
--
2.25.1

Hi,

Hi!

From: LUU HOAI <hoai.luu.ub@...>

commit b7aaa61726cbc7b941007af14a9f991a828c67e4 upstream.

As per R-Car-Gen3_Common_OPC_Customer_Notifications_V30.1.pdf,
unexpected image output(such as incorrect colors or planes being
invisible) can happen on the below conditions, as PnALPHAR register is not
initialized by reset.

...

Looks good to me this patch.
If there are no other comments and test is ok, I can apply.
Test: https://gitlab.com/cip-project/cip-kernel/linux-cip/-/pipelines/628213608

Both this and 5.10 versions look ok to me.

Best regards,
Pavel
--
People of Russia, stop Putin before his war on Ukraine escalates.

Hi!

From: LUU HOAI <hoai.luu.ub@...>

commit b7aaa61726cbc7b941007af14a9f991a828c67e4 upstream.

As per R-Car-Gen3_Common_OPC_Customer_Notifications_V30.1.pdf,
unexpected image output(such as incorrect colors or planes being
invisible) can happen on the below conditions, as PnALPHAR register
is not initialized by reset.

Thank you, applied.

Best regards,
Pavel
--
DENX Software Engineering GmbH, Managing Director: Wolfgang Denk
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany