From 091732881403de18433f399ea3106f5c1d062fd0 Mon Sep 17 00:00:00 2001
From: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
Date: Sat, 9 Apr 2022 19:57:06 +0100
Subject: drm: rcar-du: Extend CMM HDSE documentation
Git-commit: 5278027b3df1a157c7f7d8e3f7e3ba2884aaeee5
Patch-mainline: v6.0-rc1
References: jsc#PED-1166 jsc#PED-1168 jsc#PED-1170 jsc#PED-1218 jsc#PED-1220 jsc#PED-1222 jsc#PED-1223 jsc#PED-1225 jsc#PED-2849
When the CMM is enabled, the HDSE offset is further adjusted to
compensate for consumed pixels.
Explain this further, with an extra comment at the point the offset is
adjusted.
Suggested-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Acked-by: Patrik Jakobsson <pjakobsson@suse.de>
---
drivers/gpu/drm/rcar-du/rcar_du_crtc.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/drivers/gpu/drm/rcar-du/rcar_du_crtc.c b/drivers/gpu/drm/rcar-du/rcar_du_crtc.c
index f361a604337f..23e1aedf8dc0 100644
--- a/drivers/gpu/drm/rcar-du/rcar_du_crtc.c
+++ b/drivers/gpu/drm/rcar-du/rcar_du_crtc.c
@@ -300,6 +300,11 @@ static void rcar_du_crtc_set_display_timing(struct rcar_du_crtc *rcrtc)
| DSMR_DIPM_DISP | DSMR_CSPM;
rcar_du_crtc_write(rcrtc, DSMR, dsmr);
+ /*
+ * When the CMM is enabled, an additional offset of 25 pixels must be
+ * subtracted from the HDS (horizontal display start) and HDE
+ * (horizontal display end) registers.
+ */
hdse_offset = 19;
if (rcrtc->group->cmms_mask & BIT(rcrtc->index % 2))
hdse_offset += 25;
--
2.38.1