backend/drm: add support for explicit sync APIs

backend/drm/atomic.c

@@ -1,6 +1,8 @@
 #include <drm_fourcc.h>
 #include <stdlib.h>
 #include <stdio.h>
+#include <unistd.h>
+#include <wlr/render/drm_syncobj.h>
 #include <wlr/util/log.h>
 #include <xf86drm.h>
 #include <xf86drmMode.h>
@@ -272,6 +274,15 @@ bool drm_atomic_connector_prepare(struct wlr_drm_connector_state *state, bool mo
 			state->primary_fb->wlr_buf->height, &state->base->damage, &fb_damage_clips);
 	}
 
+	int in_fence_fd = -1;
+	if (state->base->committed & WLR_OUTPUT_STATE_WAIT_TIMELINE) {
+		in_fence_fd = wlr_drm_syncobj_timeline_export_sync_file(state->base->wait_timeline,
+			state->base->wait_point);
+		if (in_fence_fd < 0) {
+			return false;
+		}
+	}
+
 	bool prev_vrr_enabled =
 		output->adaptive_sync_status == WLR_OUTPUT_ADAPTIVE_SYNC_ENABLED;
 	bool vrr_enabled = prev_vrr_enabled;
@@ -285,6 +296,7 @@ bool drm_atomic_connector_prepare(struct wlr_drm_connector_state *state, bool mo
 	state->mode_id = mode_id;
 	state->gamma_lut = gamma_lut;
 	state->fb_damage_clips = fb_damage_clips;
+	state->primary_in_fence_fd = in_fence_fd;
 	state->vrr_enabled = vrr_enabled;
 	return true;
 }
@@ -305,6 +317,15 @@ void drm_atomic_connector_apply_commit(struct wlr_drm_connector_state *state) {
 		WLR_OUTPUT_ADAPTIVE_SYNC_ENABLED : WLR_OUTPUT_ADAPTIVE_SYNC_DISABLED;
 
 	destroy_blob(drm, state->fb_damage_clips);
+	if (state->primary_in_fence_fd >= 0) {
+		close(state->primary_in_fence_fd);
+	}
+	if (state->out_fence_fd >= 0) {
+		// TODO: error handling
+		wlr_drm_syncobj_timeline_import_sync_file(state->base->signal_timeline,
+			state->base->signal_point, state->out_fence_fd);
+		close(state->out_fence_fd);
+	}
 }
 
 void drm_atomic_connector_rollback_commit(struct wlr_drm_connector_state *state) {
@@ -316,6 +337,12 @@ void drm_atomic_connector_rollback_commit(struct wlr_drm_connector_state *state)
 	rollback_blob(drm, &crtc->gamma_lut, state->gamma_lut);
 
 	destroy_blob(drm, state->fb_damage_clips);
+	if (state->primary_in_fence_fd >= 0) {
+		close(state->primary_in_fence_fd);
+	}
+	if (state->out_fence_fd >= 0) {
+		close(state->out_fence_fd);
+	}
 }
 
 static void plane_disable(struct atomic *atom, struct wlr_drm_plane *plane) {
@@ -353,12 +380,37 @@ static void set_plane_props(struct atomic *atom, struct wlr_drm_backend *drm,
 	atomic_add(atom, id, props->crtc_y, (uint64_t)y);
 }
 
-static bool supports_cursor_hotspots(const struct wlr_drm_plane* plane) {
+static bool supports_cursor_hotspots(const struct wlr_drm_plane *plane) {
 	return plane->props.hotspot_x && plane->props.hotspot_y;
 }
 
+static void set_plane_in_fence_fd(struct atomic *atom,
+		struct wlr_drm_plane *plane, int sync_file_fd) {
+	if (!plane->props.in_fence_fd) {
+		wlr_log(WLR_ERROR, "Plane %"PRIu32 " is missing the IN_FENCE_FD property",
+			plane->id);
+		atom->failed = true;
+		return;
+	}
+
+	atomic_add(atom, plane->id, plane->props.in_fence_fd, sync_file_fd);
+}
+
+static void set_crtc_out_fence_ptr(struct atomic *atom, struct wlr_drm_crtc *crtc,
+		int *fd_ptr) {
+	if (!crtc->props.out_fence_ptr) {
+		wlr_log(WLR_ERROR,
+			"CRTC %"PRIu32" is missing the OUT_FENCE_PTR property",
+			crtc->id);
+		atom->failed = true;
+		return;
+	}
+
+	atomic_add(atom, crtc->id, crtc->props.out_fence_ptr, (uintptr_t)fd_ptr);
+}
+
 static void atomic_connector_add(struct atomic *atom,
-		const struct wlr_drm_connector_state *state, bool modeset) {
+		struct wlr_drm_connector_state *state, bool modeset) {
 	struct wlr_drm_connector *conn = state->connector;
 	struct wlr_drm_backend *drm = conn->backend;
 	struct wlr_drm_crtc *crtc = conn->crtc;
@@ -391,6 +443,12 @@ static void atomic_connector_add(struct atomic *atom,
 			atomic_add(atom, crtc->primary->id,
 				crtc->primary->props.fb_damage_clips, state->fb_damage_clips);
 		}
+		if (state->primary_in_fence_fd >= 0) {
+			set_plane_in_fence_fd(atom, crtc->primary, state->primary_in_fence_fd);
+		}
+		if (state->base->committed & WLR_OUTPUT_STATE_SIGNAL_TIMELINE) {
+			set_crtc_out_fence_ptr(atom, crtc, &state->out_fence_fd);
+		}
 		if (crtc->cursor) {
 			if (drm_connector_is_cursor_visible(conn)) {
 				set_plane_props(atom, drm, crtc->cursor, state->cursor_fb,

backend/drm/drm.c

@@ -42,7 +42,9 @@ static const uint32_t COMMIT_OUTPUT_STATE =
 	WLR_OUTPUT_STATE_ENABLED |
 	WLR_OUTPUT_STATE_GAMMA_LUT |
 	WLR_OUTPUT_STATE_ADAPTIVE_SYNC_ENABLED |
-	WLR_OUTPUT_STATE_LAYERS;
+	WLR_OUTPUT_STATE_LAYERS |
+	WLR_OUTPUT_STATE_WAIT_TIMELINE |
+	WLR_OUTPUT_STATE_SIGNAL_TIMELINE;
 
 static const uint32_t SUPPORTED_OUTPUT_STATE =
 	WLR_OUTPUT_STATE_BACKEND_OPTIONAL | COMMIT_OUTPUT_STATE;
@@ -630,6 +632,8 @@ static void drm_connector_state_init(struct wlr_drm_connector_state *state,
 		.connector = conn,
 		.base = base,
 		.active = output_pending_enabled(&conn->output, base),
+		.primary_in_fence_fd = -1,
+		.out_fence_fd = -1,
 	};
 
 	struct wlr_output_mode *mode = conn->output.current_mode;
@@ -1619,6 +1623,10 @@ static bool connect_drm_connector(struct wlr_drm_connector *wlr_conn,
 		output->non_desktop = non_desktop;
 	}
 
+	// TODO: support sync timelines in multi-GPU mode
+	// TODO: support sync timelines with libliftoff
+	output->timeline = drm->parent == NULL && drm->iface == &atomic_iface;
+
 	memset(wlr_conn->max_bpc_bounds, 0, sizeof(wlr_conn->max_bpc_bounds));
 	if (wlr_conn->props.max_bpc != 0) {
 		if (!introspect_drm_prop_range(drm->fd, wlr_conn->props.max_bpc,

backend/drm/properties.c

@@ -40,6 +40,7 @@ static const struct prop_info crtc_info[] = {
 	{ "GAMMA_LUT", INDEX(gamma_lut) },
 	{ "GAMMA_LUT_SIZE", INDEX(gamma_lut_size) },
 	{ "MODE_ID", INDEX(mode_id) },
+	{ "OUT_FENCE_PTR", INDEX(out_fence_ptr) },
 	{ "VRR_ENABLED", INDEX(vrr_enabled) },
 #undef INDEX
 };
@@ -55,6 +56,7 @@ static const struct prop_info plane_info[] = {
 	{ "FB_ID", INDEX(fb_id) },
 	{ "HOTSPOT_X", INDEX(hotspot_x) },
 	{ "HOTSPOT_Y", INDEX(hotspot_y) },
+	{ "IN_FENCE_FD", INDEX(in_fence_fd) },
 	{ "IN_FORMATS", INDEX(in_formats) },
 	{ "SIZE_HINTS", INDEX(size_hints) },
 	{ "SRC_H", INDEX(src_h) },

include/backend/drm/drm.h

@@ -145,6 +145,7 @@ struct wlr_drm_connector_state {
 	uint32_t mode_id;
 	uint32_t gamma_lut;
 	uint32_t fb_damage_clips;
+	int primary_in_fence_fd, out_fence_fd;
 	bool vrr_enabled;
 };
 

include/backend/drm/properties.h

@@ -38,6 +38,7 @@ struct wlr_drm_crtc_props {
 
 	uint32_t active;
 	uint32_t mode_id;
+	uint32_t out_fence_ptr;
 };
 
 struct wlr_drm_plane_props {
@@ -61,6 +62,7 @@ struct wlr_drm_plane_props {
 	uint32_t fb_damage_clips;
 	uint32_t hotspot_x;
 	uint32_t hotspot_y;
+	uint32_t in_fence_fd;
 };
 
 bool get_drm_connector_props(int fd, uint32_t id,