From 0821b26b05bf3c331d02c8ddacdb9068318a4ea8 Mon Sep 17 00:00:00 2001
From: Raphael Gallais-Pou <raphael.gallais-pou@foss.st.com>
Date: Tue, 7 Sep 2021 17:13:23 +0200
Subject: drm/stm: ltdc: attach immutable zpos property to planes
Git-commit: ee2cda7b027753fde555eae91e0f6de7f8c3ea7d
Patch-mainline: v5.16-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

Defines plane ordering by hard-coding an immutable Z position from the
first plane, used as primary layer, to the next ones as overlay in order
of instantiation.

This zpos is only an information as it is not possible to modify it,
blending operations are still applied from the top to the bottom layer.

This patch helps to remove a warning message from the Android
Hardware Composer.

Signed-off-by: Raphael Gallais-Pou <raphael.gallais-pou@foss.st.com>
Acked-by: Yannick Fertre <yannick.fertre@foss.st.com>
Reviewed-by: Yannick Fertre <yannick.fertre@foss.st.com>
Signed-off-by: Philippe Cornu <philippe.cornu@foss.st.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210907151323.5850-1-raphael.gallais-pou@foss.st.com
Acked-by: Patrik Jakobsson <pjakobsson@suse.de>
---
 drivers/gpu/drm/stm/ltdc.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/stm/ltdc.c b/drivers/gpu/drm/stm/ltdc.c
index 195de30eb90c..bd603ef5e935 100644
--- a/drivers/gpu/drm/stm/ltdc.c
+++ b/drivers/gpu/drm/stm/ltdc.c
@@ -1024,6 +1024,8 @@ static int ltdc_crtc_init(struct drm_device *ddev, struct drm_crtc *crtc)
 		return -EINVAL;
 	}
 
+	drm_plane_create_zpos_immutable_property(primary, 0);
+
 	ret = drm_crtc_init_with_planes(ddev, crtc, primary, NULL,
 					&ltdc_crtc_funcs, NULL);
 	if (ret) {
@@ -1046,6 +1048,7 @@ static int ltdc_crtc_init(struct drm_device *ddev, struct drm_crtc *crtc)
 			DRM_ERROR("Can not create overlay plane %d\n", i);
 			goto cleanup;
 		}
+		drm_plane_create_zpos_immutable_property(overlay, i);
 	}
 
 	return 0;
-- 
2.38.1