backend/drm: add support for output layers

backend/drm/drm.c

@@ -42,7 +42,8 @@ static const uint32_t COMMIT_OUTPUT_STATE =
 	WLR_OUTPUT_STATE_MODE |
 	WLR_OUTPUT_STATE_ENABLED |
 	WLR_OUTPUT_STATE_GAMMA_LUT |
-	WLR_OUTPUT_STATE_ADAPTIVE_SYNC_ENABLED;
+	WLR_OUTPUT_STATE_ADAPTIVE_SYNC_ENABLED |
+	WLR_OUTPUT_STATE_LAYERS;
 
 static const uint32_t SUPPORTED_OUTPUT_STATE =
 	WLR_OUTPUT_STATE_BACKEND_OPTIONAL | COMMIT_OUTPUT_STATE;
@@ -276,6 +277,8 @@ bool init_drm_resources(struct wlr_drm_backend *drm) {
 		if (!get_drm_crtc_props(drm->fd, crtc->id, &crtc->props)) {
 			goto error_crtcs;
 		}
+
+		wl_list_init(&crtc->layers);
 	}
 
 	if (!init_planes(drm)) {
@@ -336,6 +339,64 @@ static struct wlr_drm_connector *get_drm_connector_from_output(
 	return (struct wlr_drm_connector *)wlr_output;
 }
 
+static void layer_handle_addon_destroy(struct wlr_addon *addon) {
+	struct wlr_drm_layer *layer = wl_container_of(addon, layer, addon);
+	wlr_addon_finish(&layer->addon);
+	wl_list_remove(&layer->link);
+#if HAVE_LIBLIFTOFF
+	liftoff_layer_destroy(layer->liftoff);
+#endif
+	drm_fb_clear(&layer->pending_fb);
+	drm_fb_clear(&layer->queued_fb);
+	drm_fb_clear(&layer->current_fb);
+	free(layer);
+}
+
+const struct wlr_addon_interface layer_impl = {
+	.name = "wlr_drm_layer",
+	.destroy = layer_handle_addon_destroy,
+};
+
+struct wlr_drm_layer *get_drm_layer(struct wlr_drm_backend *drm,
+		struct wlr_output_layer *wlr_layer) {
+	struct wlr_addon *addon =
+		wlr_addon_find(&wlr_layer->addons, drm, &layer_impl);
+	assert(addon != NULL);
+	struct wlr_drm_layer *layer = wl_container_of(addon, layer, addon);
+	return layer;
+}
+
+static struct wlr_drm_layer *get_or_create_layer(struct wlr_drm_backend *drm,
+		struct wlr_drm_crtc *crtc, struct wlr_output_layer *wlr_layer) {
+	struct wlr_drm_layer *layer;
+	struct wlr_addon *addon =
+		wlr_addon_find(&wlr_layer->addons, drm, &layer_impl);
+	if (addon != NULL) {
+		layer = wl_container_of(addon, layer, addon);
+		return layer;
+	}
+
+	layer = calloc(1, sizeof(*layer));
+	if (layer == NULL) {
+		return NULL;
+	}
+
+#if HAVE_LIBLIFTOFF
+	layer->liftoff = liftoff_layer_create(crtc->liftoff);
+	if (layer->liftoff == NULL) {
+		free(layer);
+		return NULL;
+	}
+#else
+	abort(); // unreachable
+#endif
+
+	wlr_addon_init(&layer->addon, &wlr_layer->addons, drm, &layer_impl);
+	wl_list_insert(&crtc->layers, &layer->link);
+
+	return layer;
+}
+
 static bool drm_crtc_commit(struct wlr_drm_connector *conn,
 		const struct wlr_drm_connector_state *state,
 		uint32_t flags, bool test_only) {
@@ -353,6 +414,11 @@ static bool drm_crtc_commit(struct wlr_drm_connector *conn,
 		if (crtc->cursor != NULL) {
 			drm_fb_move(&crtc->cursor->queued_fb, &conn->cursor_pending_fb);
 		}
+
+		struct wlr_drm_layer *layer;
+		wl_list_for_each(layer, &crtc->layers, link) {
+			drm_fb_move(&layer->queued_fb, &layer->pending_fb);
+		}
 	} else {
 		// The set_cursor() hook is a bit special: it's not really synchronized
 		// to commit() or test(). Once set_cursor() returns true, the new
@@ -360,6 +426,11 @@ static bool drm_crtc_commit(struct wlr_drm_connector *conn,
 		// risk ending up in a state where we don't have a cursor FB but
 		// wlr_drm_connector.cursor_enabled is true.
 		// TODO: fix our output interface to avoid this issue.
+
+		struct wlr_drm_layer *layer;
+		wl_list_for_each(layer, &crtc->layers, link) {
+			drm_fb_clear(&layer->pending_fb);
+		}
 	}
 	return ok;
 }
@@ -457,6 +528,42 @@ static bool drm_connector_state_update_primary_fb(struct wlr_drm_connector *conn
 	return true;
 }
 
+static bool drm_connector_set_pending_layer_fbs(struct wlr_drm_connector *conn,
+		const struct wlr_output_state *state) {
+	struct wlr_drm_backend *drm = conn->backend;
+
+	struct wlr_drm_crtc *crtc = conn->crtc;
+	if (!crtc || drm->parent) {
+		return false;
+	}
+
+	if (!crtc->liftoff) {
+		return true; // libliftoff is disabled
+	}
+
+	assert(state->committed & WLR_OUTPUT_STATE_LAYERS);
+
+	for (size_t i = 0; i < state->layers_len; i++) {
+		struct wlr_output_layer_state *layer_state = &state->layers[i];
+		struct wlr_drm_layer *layer =
+			get_or_create_layer(drm, crtc, layer_state->layer);
+		if (!layer) {
+			return false;
+		}
+
+		if (layer_state->buffer != NULL) {
+			layer->pending_width = layer_state->buffer->width;
+			layer->pending_height = layer_state->buffer->height;
+			drm_fb_import(&layer->pending_fb, drm, layer_state->buffer, NULL);
+		} else {
+			layer->pending_width = layer->pending_height = 0;
+			drm_fb_clear(&layer->pending_fb);
+		}
+	}
+
+	return true;
+}
+
 static bool drm_connector_alloc_crtc(struct wlr_drm_connector *conn);
 
 static bool drm_connector_test(struct wlr_output *output,
@@ -533,6 +640,11 @@ static bool drm_connector_test(struct wlr_output *output,
 			goto out;
 		}
 	}
+	if (state->committed & WLR_OUTPUT_STATE_LAYERS) {
+		if (!drm_connector_set_pending_layer_fbs(conn, pending.base)) {
+			return false;
+		}
+	}
 
 	ok = drm_crtc_commit(conn, &pending, 0, true);
 
@@ -618,6 +730,11 @@ bool drm_connector_commit_state(struct wlr_drm_connector *conn,
 	if (pending.modeset && pending.active) {
 		flags |= DRM_MODE_PAGE_FLIP_EVENT;
 	}
+	if (pending.base->committed & WLR_OUTPUT_STATE_LAYERS) {
+		if (!drm_connector_set_pending_layer_fbs(conn, pending.base)) {
+			return false;
+		}
+	}
 
 	if (pending.modeset) {
 		if (pending.active) {
@@ -1564,6 +1681,11 @@ static void handle_page_flip(int fd, unsigned seq,
 			&conn->crtc->cursor->queued_fb);
 	}
 
+	struct wlr_drm_layer *layer;
+	wl_list_for_each(layer, &conn->crtc->layers, link) {
+		drm_fb_move(&layer->current_fb, &layer->queued_fb);
+	}
+
 	uint32_t present_flags = WLR_OUTPUT_PRESENT_VSYNC |
 		WLR_OUTPUT_PRESENT_HW_CLOCK | WLR_OUTPUT_PRESENT_HW_COMPLETION;
 	/* Don't report ZERO_COPY in multi-gpu situations, because we had to copy

backend/drm/libliftoff.c

@@ -142,10 +142,9 @@ static void rollback_blob(struct wlr_drm_backend *drm,
 }
 
 static bool set_plane_props(struct wlr_drm_plane *plane,
-		struct liftoff_layer *layer, int32_t x, int32_t y, uint64_t zpos) {
-	struct wlr_drm_fb *fb = plane_get_next_fb(plane);
+		struct liftoff_layer *layer, struct wlr_drm_fb *fb, int32_t x, int32_t y, uint64_t zpos) {
 	if (fb == NULL) {
-		wlr_log(WLR_ERROR, "Failed to acquire FB");
+		wlr_log(WLR_ERROR, "Failed to acquire FB for plane %"PRIu32, plane->id);
 		return false;
 	}
 
@@ -169,6 +168,52 @@ static bool disable_plane(struct wlr_drm_plane *plane) {
 	return liftoff_layer_set_property(plane->liftoff_layer, "FB_ID", 0) == 0;
 }
 
+static uint64_t to_fp16(double v) {
+	return (uint64_t)round(v * (1 << 16));
+}
+
+static bool set_layer_props(struct wlr_drm_backend *drm,
+		const struct wlr_output_layer_state *state, uint64_t zpos) {
+	struct wlr_drm_layer *layer = get_drm_layer(drm, state->layer);
+
+	struct wlr_drm_fb *fb = layer->pending_fb;
+	int ret = 0;
+	if (state->buffer == NULL) {
+		ret = liftoff_layer_set_property(layer->liftoff, "FB_ID", 0);
+	} else if (fb == NULL) {
+		liftoff_layer_set_fb_composited(layer->liftoff);
+	} else {
+		ret = liftoff_layer_set_property(layer->liftoff, "FB_ID", fb->id);
+	}
+	if (ret != 0) {
+		return false;
+	}
+
+	uint32_t width = layer->pending_width;
+	uint32_t height = layer->pending_height;
+
+	uint64_t crtc_x = (uint64_t)state->x;
+	uint64_t crtc_y = (uint64_t)state->y;
+	uint64_t crtc_w = (uint64_t)width;
+	uint64_t crtc_h = (uint64_t)height;
+
+	uint64_t src_x = to_fp16(0);
+	uint64_t src_y = to_fp16(0);
+	uint64_t src_w = to_fp16(width);
+	uint64_t src_h = to_fp16(height);
+
+	return
+		liftoff_layer_set_property(layer->liftoff, "zpos", zpos) == 0 &&
+		liftoff_layer_set_property(layer->liftoff, "CRTC_X", crtc_x) == 0 &&
+		liftoff_layer_set_property(layer->liftoff, "CRTC_Y", crtc_y) == 0 &&
+		liftoff_layer_set_property(layer->liftoff, "CRTC_W", crtc_w) == 0 &&
+		liftoff_layer_set_property(layer->liftoff, "CRTC_H", crtc_h) == 0 &&
+		liftoff_layer_set_property(layer->liftoff, "SRC_X", src_x) == 0 &&
+		liftoff_layer_set_property(layer->liftoff, "SRC_Y", src_y) == 0 &&
+		liftoff_layer_set_property(layer->liftoff, "SRC_W", src_w) == 0 &&
+		liftoff_layer_set_property(layer->liftoff, "SRC_H", src_h) == 0;
+}
+
 static bool crtc_commit(struct wlr_drm_connector *conn,
 		const struct wlr_drm_connector_state *state, uint32_t flags,
 		bool test_only) {
@@ -272,16 +317,25 @@ static bool crtc_commit(struct wlr_drm_connector *conn,
 			ok = ok && add_prop(req, crtc->id, crtc->props.vrr_enabled, vrr_enabled);
 		}
 		ok = ok &&
-			set_plane_props(crtc->primary, crtc->primary->liftoff_layer, 0, 0, 0) &&
-			set_plane_props(crtc->primary, crtc->liftoff_composition_layer, 0, 0, 0);
+			set_plane_props(crtc->primary, crtc->primary->liftoff_layer, state->primary_fb, 0, 0, 0) &&
+			set_plane_props(crtc->primary, crtc->liftoff_composition_layer, state->primary_fb, 0, 0, 0);
 		liftoff_layer_set_property(crtc->primary->liftoff_layer,
 			"FB_DAMAGE_CLIPS", fb_damage_clips);
 		liftoff_layer_set_property(crtc->liftoff_composition_layer,
 			"FB_DAMAGE_CLIPS", fb_damage_clips);
+
+		if (state->base->committed & WLR_OUTPUT_STATE_LAYERS) {
+			for (size_t i = 0; i < state->base->layers_len; i++) {
+				const struct wlr_output_layer_state *layer_state = &state->base->layers[i];
+				ok = ok && set_layer_props(drm, layer_state, i + 1);
+			}
+		}
+
 		if (crtc->cursor) {
 			if (drm_connector_is_cursor_visible(conn)) {
 				ok = ok && set_plane_props(crtc->cursor, crtc->cursor->liftoff_layer,
-					conn->cursor_x, conn->cursor_y, 1);
+					get_next_cursor_fb(conn), conn->cursor_x, conn->cursor_y,
+					wl_list_length(&crtc->layers) + 1);
 			} else {
 				ok = ok && disable_plane(crtc->cursor);
 			}
@@ -320,6 +374,15 @@ static bool crtc_commit(struct wlr_drm_connector *conn,
 		goto out;
 	}
 
+	if (state->base->committed & WLR_OUTPUT_STATE_LAYERS) {
+		for (size_t i = 0; i < state->base->layers_len; i++) {
+			struct wlr_output_layer_state *layer_state = &state->base->layers[i];
+			struct wlr_drm_layer *layer = get_drm_layer(drm, layer_state->layer);
+			layer_state->accepted =
+				!liftoff_layer_needs_composition(layer->liftoff);
+		}
+	}
+
 out:
 	drmModeAtomicFree(req);
 

include/backend/drm/drm.h

@@ -10,6 +10,7 @@
 #include <wlr/backend/drm.h>
 #include <wlr/backend/session.h>
 #include <wlr/render/drm_format_set.h>
+#include <wlr/types/wlr_output_layer.h>
 #include <xf86drmMode.h>
 #include "backend/drm/iface.h"
 #include "backend/drm/properties.h"
@@ -36,11 +37,27 @@ struct wlr_drm_plane {
 	struct liftoff_layer *liftoff_layer;
 };
 
+struct wlr_drm_layer {
+	struct liftoff_layer *liftoff;
+	struct wlr_addon addon; // wlr_output_layer.addons
+	struct wl_list link; // wlr_drm_crtc.layers
+
+	/* Buffer to be submitted to the kernel on the next page-flip */
+	struct wlr_drm_fb *pending_fb;
+	/* Buffer submitted to the kernel, will be presented on next vblank */
+	struct wlr_drm_fb *queued_fb;
+	/* Buffer currently displayed on screen */
+	struct wlr_drm_fb *current_fb;
+
+	int pending_width, pending_height;
+};
+
 struct wlr_drm_crtc {
 	uint32_t id;
 	struct wlr_drm_lease *lease;
 	struct liftoff_output *liftoff;
 	struct liftoff_layer *liftoff_composition_layer;
+	struct wl_list layers; // wlr_drm_layer.link
 
 	// Atomic modesetting only
 	uint32_t mode_id;
@@ -163,6 +180,8 @@ size_t drm_crtc_get_gamma_lut_size(struct wlr_drm_backend *drm,
 void drm_lease_destroy(struct wlr_drm_lease *lease);
 
 struct wlr_drm_fb *get_next_cursor_fb(struct wlr_drm_connector *conn);
+struct wlr_drm_layer *get_drm_layer(struct wlr_drm_backend *drm,
+	struct wlr_output_layer *layer);
 
 #define wlr_drm_conn_log(conn, verb, fmt, ...) \
 	wlr_log(verb, "connector %s: " fmt, conn->name, ##__VA_ARGS__)