HX5449: cfg-open task: enter, 1 x 250 ms READ_STATUS + hz/10 pause (fix: abort on error)
HX5449[B]: closer: HUPCL line task + queue cfg_close + usb_proc_mwait() (uninterruptible, usb_serial.c:671-672) behind the open chain
HX5449[B]: closer: unblocked  ELAPSED=1285 ms