int tb_switch_resume()

in switch.c [2952:3034]

• 58 lines of code
• 16 McCabe index (conditional complexity)

int tb_switch_resume(struct tb_switch *sw)
{
	struct tb_port *port;
	int err;

	tb_sw_dbg(sw, "resuming switch\n");

	/*
	 * Check for UID of the connected switches except for root
	 * switch which we assume cannot be removed.
	 */
	if (tb_route(sw)) {
		u64 uid;

		/*
		 * Check first that we can still read the switch config
		 * space. It may be that there is now another domain
		 * connected.
		 */
		err = tb_cfg_get_upstream_port(sw->tb->ctl, tb_route(sw));
		if (err < 0) {
			tb_sw_info(sw, "switch not present anymore\n");
			return err;
		}

		if (tb_switch_is_usb4(sw))
			err = usb4_switch_read_uid(sw, &uid);
		else
			err = tb_drom_read_uid_only(sw, &uid);
		if (err) {
			tb_sw_warn(sw, "uid read failed\n");
			return err;
		}
		if (sw->uid != uid) {
			tb_sw_info(sw,
				"changed while suspended (uid %#llx -> %#llx)\n",
				sw->uid, uid);
			return -ENODEV;
		}
	}

	err = tb_switch_configure(sw);
	if (err)
		return err;

	/* Disable wakes */
	tb_switch_set_wake(sw, 0);

	err = tb_switch_tmu_init(sw);
	if (err)
		return err;

	/* check for surviving downstream switches */
	tb_switch_for_each_port(sw, port) {
		if (!tb_port_is_null(port))
			continue;

		if (!tb_port_resume(port))
			continue;

		if (tb_wait_for_port(port, true) <= 0) {
			tb_port_warn(port,
				     "lost during suspend, disconnecting\n");
			if (tb_port_has_remote(port))
				tb_sw_set_unplugged(port->remote->sw);
			else if (port->xdomain)
				port->xdomain->is_unplugged = true;
		} else {
			/*
			 * Always unlock the port so the downstream
			 * switch/domain is accessible.
			 */
			if (tb_port_unlock(port))
				tb_port_warn(port, "failed to unlock port\n");
			if (port->remote && tb_switch_resume(port->remote->sw)) {
				tb_port_warn(port,
					     "lost during suspend, disconnecting\n");
				tb_sw_set_unplugged(port->remote->sw);
			}
		}
	}
	return 0;
}