UC5504: DF-5504 ucycom cfg-stall harness (verbatim extraction, hz=100); ucycom chain shape: 1x1000ms EP0 per cfg_open/cfg_param task + hz/10 core pause
UC5504[A]: === phase A (baseline): first open + 1 tcsetattr(s) + close, silent device
UC5504:   EP0 -> bmRequestType=0x21 bRequest=0x09 (UR_SET_REPORT) wValue=0x0300 wIndex=0 wLength=32, timo=1000 ms, evil=silent -> USB_ERR_TIMEOUT (discarded, ucycom.c:440-443)
UC5504[A]: closer: queue cfg_close + usb_proc_mwait() (uninterruptible, usb_serial.c:671-672)
UC5504:   EP0 -> bmRequestType=0x21 bRequest=0x09 (UR_SET_REPORT) wValue=0x0300 wIndex=0 wLength=32, timo=1000 ms, evil=silent -> USB_ERR_TIMEOUT (discarded, ucycom.c:440-443)
UC5504[A]: closer: unblocked  ELAPSED=2107 ms (2 EP0 requests burned)
UC5504[2]: === phase A2 (2 tcsetattrs): first open + 2 tcsetattr(s) + close, silent device
UC5504:   EP0 -> bmRequestType=0x21 bRequest=0x09 (UR_SET_REPORT) wValue=0x0300 wIndex=0 wLength=32, timo=1000 ms, evil=silent -> USB_ERR_TIMEOUT (discarded, ucycom.c:440-443)
UC5504[2]: closer: queue cfg_close + usb_proc_mwait() (uninterruptible, usb_serial.c:671-672)
UC5504:   EP0 -> bmRequestType=0x21 bRequest=0x09 (UR_SET_REPORT) wValue=0x0300 wIndex=0 wLength=32, timo=1000 ms, evil=silent -> USB_ERR_TIMEOUT (discarded, ucycom.c:440-443)
UC5504[2]: closer: unblocked  ELAPSED=2108 ms (2 EP0 requests burned)
UC5504[S]: === phase S (slow-answer: no error to propagate): first open + 1 tcsetattr(s) + close, answers-at-950ms device
UC5504:   EP0 -> bmRequestType=0x21 bRequest=0x09 (UR_SET_REPORT) wValue=0x0300 wIndex=0 wLength=32, timo=1000 ms, evil=answers at timo-50 (SUCCESS)
UC5504[S]: closer: queue cfg_close + usb_proc_mwait() (uninterruptible, usb_serial.c:671-672)
UC5504:   EP0 -> bmRequestType=0x21 bRequest=0x09 (UR_SET_REPORT) wValue=0x0300 wIndex=0 wLength=32, timo=1000 ms, evil=answers at timo-50 (SUCCESS)
UC5504[S]: closer: unblocked  ELAPSED=1997 ms (2 EP0 requests burned)
UC5504[C]: === phase C (fix: 250 ms cfg timeout): first open + 1 tcsetattr(s) + close, silent device, UCYCOM_CFG_TIMEOUT=250 fix modeled
UC5504:   EP0 -> bmRequestType=0x21 bRequest=0x09 (UR_SET_REPORT) wValue=0x0300 wIndex=0 wLength=32, timo=250 ms, evil=silent -> USB_ERR_TIMEOUT (discarded, ucycom.c:440-443)
UC5504[C]: closer: queue cfg_close + usb_proc_mwait() (uninterruptible, usb_serial.c:671-672)
UC5504:   EP0 -> bmRequestType=0x21 bRequest=0x09 (UR_SET_REPORT) wValue=0x0300 wIndex=0 wLength=32, timo=250 ms, evil=silent -> USB_ERR_TIMEOUT (discarded, ucycom.c:440-443)
UC5504[C]: closer: unblocked  ELAPSED=638 ms (2 EP0 requests burned)
UC5504: harness complete