1 files changed, 41 insertions, 1 deletions

diff --git a/backend/drm/drm.c b/backend/drm/drm.c
index 10485a8a..10564305 100644
--- a/backend/drm/drm.c
+++ b/backend/drm/drm.c
@@ -766,7 +766,7 @@ bool drm_connector_supports_vrr(struct wlr_drm_connector *conn) {
 	return true;
 }
 
-bool drm_connector_commit_state(struct wlr_drm_connector *conn,
+static bool drm_connector_commit_state(struct wlr_drm_connector *conn,
 		const struct wlr_output_state *base) {
 	struct wlr_drm_backend *drm = conn->backend;
 
@@ -1720,6 +1720,46 @@ void scan_drm_leases(struct wlr_drm_backend *drm) {
 	drmFree(list);
 }
 
+static void build_current_connector_state(struct wlr_output_state *state,
+		struct wlr_drm_connector *conn) {
+	bool enabled = conn->status != DRM_MODE_DISCONNECTED && conn->output.enabled;
+
+	wlr_output_state_init(state);
+	wlr_output_state_set_enabled(state, enabled);
+	if (!enabled) {
+		return;
+	}
+
+	if (conn->output.current_mode != NULL) {
+		wlr_output_state_set_mode(state, conn->output.current_mode);
+	} else {
+		wlr_output_state_set_custom_mode(state,
+			conn->output.width, conn->output.height, conn->output.refresh);
+	}
+}
+
+void restore_drm_device(struct wlr_drm_backend *drm) {
+	// The previous DRM master leaves KMS in an undefined state. We need
+	// to restore out own state, but be careful to avoid invalid
+	// configurations. The connector/CRTC mapping may have changed, so
+	// first disable all CRTCs, then light up the ones we were using
+	// before the VT switch.
+	// TODO: better use the atomic API to improve restoration after a VT switch
+	if (!drm->iface->reset(drm)) {
+		wlr_log(WLR_ERROR, "Failed to reset state after VT switch");
+	}
+
+	struct wlr_drm_connector *conn;
+	wl_list_for_each(conn, &drm->connectors, link) {
+		struct wlr_output_state state;
+		build_current_connector_state(&state, conn);
+		if (!drm_connector_commit_state(conn, &state)) {
+			wlr_drm_conn_log(conn, WLR_ERROR, "Failed to restore state after VT switch");
+		}
+		wlr_output_state_finish(&state);
+	}
+}
+
 static int mhz_to_nsec(int mhz) {
 	return 1000000000000LL / mhz;
 }