From bb5f268b7662469b47e9b518c2353803bc7f4ec9 Mon Sep 17 00:00:00 2001 From: Tomi Valkeinen Date: Tue, 17 Dec 2024 07:31:36 +0200 Subject: [PATCH] drm/rcar-du: Write DPTSR only if the second source exists Currently the driver always writes DPTSR when setting up the hardware. However, writing the register is only meaningful when the second source for a plane is used, and the register is not even documented for SoCs that do not have the second source. So move the write behind a condition. Signed-off-by: Tomi Valkeinen Reviewed-by: Laurent Pinchart Tested-by: Laurent Pinchart # On R-Car M3-N Signed-off-by: Tomi Valkeinen Link: https://patchwork.freedesktop.org/patch/msgid/20241217-rcar-gh-dsi-v5-2-e77421093c05@ideasonboard.com --- .../gpu/drm/renesas/rcar-du/rcar_du_group.c | 20 ++++++++++++++----- 1 file changed, 15 insertions(+), 5 deletions(-) diff --git a/drivers/gpu/drm/renesas/rcar-du/rcar_du_group.c b/drivers/gpu/drm/renesas/rcar-du/rcar_du_group.c index 2ccd2581f544..1ec806c8e013 100644 --- a/drivers/gpu/drm/renesas/rcar-du/rcar_du_group.c +++ b/drivers/gpu/drm/renesas/rcar-du/rcar_du_group.c @@ -185,11 +185,21 @@ static void rcar_du_group_setup(struct rcar_du_group *rgrp) dorcr |= DORCR_PG1T | DORCR_DK1S | DORCR_PG1D_DS1; rcar_du_group_write(rgrp, DORCR, dorcr); - /* Apply planes to CRTCs association. */ - mutex_lock(&rgrp->lock); - rcar_du_group_write(rgrp, DPTSR, (rgrp->dptsr_planes << 16) | - rgrp->dptsr_planes); - mutex_unlock(&rgrp->lock); + /* + * DPTSR is used to select the source for the planes of a group. The + * first source is chosen by writing 0 to the respective bits, and this + * is always the default value of the register. In other words, writing + * DPTSR is only needed if the SoC supports choosing the second source. + * + * The SoCs documentations seems to confirm this, as the DPTSR register + * is not documented if only the first source exists on that SoC. + */ + if (rgrp->channels_mask & BIT(1)) { + mutex_lock(&rgrp->lock); + rcar_du_group_write(rgrp, DPTSR, (rgrp->dptsr_planes << 16) | + rgrp->dptsr_planes); + mutex_unlock(&rgrp->lock); + } } /* -- 2.50.1