Quoting Biju Das (2022-04-26 09:41:57)
From: LUU HOAI hoai.luu.ub@renesas.com
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@renesas.com Signed-off-by: Biju Das biju.das.jz@bp.renesas.com
v1->v2:
- Updated commit description
- Updated the code comments
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 f214a8b6cfd3..aa80c44dd8d7 100644 --- a/drivers/gpu/drm/rcar-du/rcar_du_plane.c +++ b/drivers/gpu/drm/rcar-du/rcar_du_plane.c @@ -510,6 +510,18 @@ 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.*/
Sounds reasonable.
/* TODO: Check if alpha-blending should be disabled in PnMR. */
How will this be done? Do you have a specific test in mind to determine if it causes issues? Or does it need validating through the hardware teams?
rcar_du_plane_write(rgrp, index, PnALPHAR, 0);
Reviewed-by: Kieran Bingham kieran.bingham+renesas@ideasonboard.com
}
static void rcar_du_plane_setup_format(struct rcar_du_group *rgrp,
2.25.1