From 5225183c3901ab935c96ef062a08c9348984fd69 Mon Sep 17 00:00:00 2001
From: Dave Stevenson <dave.stevenson@raspberrypi.com>
Date: Tue, 15 Aug 2023 15:44:34 +0100
Subject: [PATCH] drm/vc4: Assign 32 overlay planes to writeback only

Instead of having 48 generic overlay planes, assign 32 to the
writeback connector so that there is no ambiguity in wlroots
when trying to find a plane for composition using the writeback
connector vs display.

Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
---
 drivers/gpu/drm/vc4/vc4_plane.c | 34 +++++++++++++++++++++++++++++++--
 1 file changed, 32 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/vc4/vc4_plane.c b/drivers/gpu/drm/vc4/vc4_plane.c
index 96235f8d94da4..bbdb531f494b7 100644
--- a/drivers/gpu/drm/vc4/vc4_plane.c
+++ b/drivers/gpu/drm/vc4/vc4_plane.c
@@ -2450,13 +2450,28 @@ struct drm_plane *vc4_plane_init(struct drm_device *dev,
 	return plane;
 }
 
-#define VC4_NUM_OVERLAY_PLANES	48
+#define VC4_NUM_OVERLAY_PLANES	16
+#define VC4_NUM_TXP_OVERLAY_PLANES 32
 
 int vc4_plane_create_additional_planes(struct drm_device *drm)
 {
 	struct drm_plane *cursor_plane;
 	struct drm_crtc *crtc;
 	unsigned int i;
+	struct drm_crtc *txp_crtc;
+	uint32_t non_txp_crtc_mask;
+
+	drm_for_each_crtc(crtc, drm) {
+		struct vc4_crtc *vc4_crtc = to_vc4_crtc(crtc);
+
+		if (vc4_crtc->feeds_txp) {
+			txp_crtc = crtc;
+			break;
+		}
+	}
+
+	non_txp_crtc_mask = GENMASK(drm->mode_config.num_crtc - 1, 0) -
+					drm_crtc_mask(txp_crtc);
 
 	/* Set up some arbitrary number of planes.  We're not limited
 	 * by a set number of physical registers, just the space in
@@ -2470,7 +2485,22 @@ int vc4_plane_create_additional_planes(struct drm_device *drm)
 	for (i = 0; i < VC4_NUM_OVERLAY_PLANES; i++) {
 		struct drm_plane *plane =
 			vc4_plane_init(drm, DRM_PLANE_TYPE_OVERLAY,
-				       GENMASK(drm->mode_config.num_crtc - 1, 0));
+				       non_txp_crtc_mask);
+
+		if (IS_ERR(plane))
+			continue;
+
+		/* Create zpos property. Max of all the overlays + 1 primary +
+		 * 1 cursor plane on a crtc.
+		 */
+		drm_plane_create_zpos_property(plane, i + 1, 1,
+					       VC4_NUM_OVERLAY_PLANES + 1);
+	}
+
+	for (i = 0; i < VC4_NUM_TXP_OVERLAY_PLANES; i++) {
+		struct drm_plane *plane =
+			vc4_plane_init(drm, DRM_PLANE_TYPE_OVERLAY,
+				       drm_crtc_mask(txp_crtc));
 
 		if (IS_ERR(plane))
 			continue;