drm/vc4: hvs: Support zpos on all planes

Adds the zpos property to all planes, and creates the dlist
by placing the fragments in the correct order based on zpos.
Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
Link: https://lore.kernel.org/r/20221207-rpi-hvs-crtc-misc-v1-5-1f8e0770798b@cerno.techSigned-off-by: Maxime Ripard <maxime@cerno.tech>

drivers/gpu/drm/vc4/vc4_hvs.c

@@ -570,6 +570,8 @@ void vc4_hvs_atomic_flush(struct drm_crtc *crtc,
 	bool enable_bg_fill = false;
 	u32 __iomem *dlist_start = vc4->hvs->dlist + vc4_state->mm.start;
 	u32 __iomem *dlist_next = dlist_start;
+	unsigned int zpos = 0;
+	bool found = false;
 	int idx;
 
 	if (!drm_dev_enter(dev, &idx)) {
@@ -583,23 +585,34 @@ void vc4_hvs_atomic_flush(struct drm_crtc *crtc,
 	}
 
 	/* Copy all the active planes' dlist contents to the hardware dlist. */
-	drm_atomic_crtc_for_each_plane(plane, crtc) {
-		/* Is this the first active plane? */
-		if (dlist_next == dlist_start) {
-			/* We need to enable background fill when a plane
-			 * could be alpha blending from the background, i.e.
-			 * where no other plane is underneath. It suffices to
-			 * consider the first active plane here since we set
-			 * needs_bg_fill such that either the first plane
-			 * already needs it or all planes on top blend from
-			 * the first or a lower plane.
-			 */
-			vc4_plane_state = to_vc4_plane_state(plane->state);
-			enable_bg_fill = vc4_plane_state->needs_bg_fill;
+	do {
+		found = false;
+
+		drm_atomic_crtc_for_each_plane(plane, crtc) {
+			if (plane->state->normalized_zpos != zpos)
+				continue;
+
+			/* Is this the first active plane? */
+			if (dlist_next == dlist_start) {
+				/* We need to enable background fill when a plane
+				 * could be alpha blending from the background, i.e.
+				 * where no other plane is underneath. It suffices to
+				 * consider the first active plane here since we set
+				 * needs_bg_fill such that either the first plane
+				 * already needs it or all planes on top blend from
+				 * the first or a lower plane.
+				 */
+				vc4_plane_state = to_vc4_plane_state(plane->state);
+				enable_bg_fill = vc4_plane_state->needs_bg_fill;
+			}
+
+			dlist_next += vc4_plane_write_dlist(plane, dlist_next);
+
+			found = true;
 		}
 
-		dlist_next += vc4_plane_write_dlist(plane, dlist_next);
-	}
+		zpos++;
+	} while (found);
 
 	writel(SCALER_CTL0_END, dlist_next);
 	dlist_next++;

drivers/gpu/drm/vc4/vc4_kms.c

@@ -1074,6 +1074,7 @@ int vc4_kms_load(struct drm_device *dev)
 	dev->mode_config.helper_private = &vc4_mode_config_helpers;
 	dev->mode_config.preferred_depth = 24;
 	dev->mode_config.async_page_flip = true;
+	dev->mode_config.normalize_zpos = true;
 
 	ret = vc4_ctm_obj_init(vc4);
 	if (ret)

drivers/gpu/drm/vc4/vc4_plane.c

@@ -1568,9 +1568,14 @@ struct drm_plane *vc4_plane_init(struct drm_device *dev,
 					  DRM_COLOR_YCBCR_BT709,
 					  DRM_COLOR_YCBCR_LIMITED_RANGE);
 
+	if (type == DRM_PLANE_TYPE_PRIMARY)
+		drm_plane_create_zpos_immutable_property(plane, 0);
+
 	return plane;
 }
 
+#define VC4_NUM_OVERLAY_PLANES	16
+
 int vc4_plane_create_additional_planes(struct drm_device *drm)
 {
 	struct drm_plane *cursor_plane;
@@ -1586,24 +1591,35 @@ int vc4_plane_create_additional_planes(struct drm_device *drm)
 	 * modest number of planes to expose, that should hopefully
 	 * still cover any sane usecase.
 	 */
-	for (i = 0; i < 16; i++) {
+	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));
 
 		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);
 	}
 
 	drm_for_each_crtc(crtc, drm) {
 		/* Set up the legacy cursor after overlay initialization,
-		 * since we overlay planes on the CRTC in the order they were
-		 * initialized.
+		 * since the zpos fallback is that planes are rendered by plane
+		 * ID order, and that then puts the cursor on top.
 		 */
 		cursor_plane = vc4_plane_init(drm, DRM_PLANE_TYPE_CURSOR,
 					      drm_crtc_mask(crtc));
 		if (!IS_ERR(cursor_plane)) {
 			crtc->cursor = cursor_plane;
+
+			drm_plane_create_zpos_property(cursor_plane,
+						       VC4_NUM_OVERLAY_PLANES + 1,
+						       1,
+						       VC4_NUM_OVERLAY_PLANES + 1);
 		}
 	}