usbdump(8) question

[Yuri]

I am trying to use usbdump(8) on one webcam, but the produced, log 
causes some questions.

1. Why -s 1024 option doesn't show actual data even though SLEN for 
packets is non-zero?
2. When I run webcamd, first 4 lines of log (with the error) quickly 
appear. Webcamd exits quickly, in 0.035s, but usbdump after 1-2 secs 
shows the rest of the log. Why is this significant delay? Why the first 
4 lines aren't delayed?

Yuri


--- usbdump log ---
# usbdump -i usbus3 -s 1024
12:32:19.151777 usbus3.2 SUBM-CTRL-EP=00000080,SPD=HIGH,NFR=2,SLEN=8,IVAL=0
12:32:19.155753 usbus3.2 
DONE-CTRL-EP=00000080,SPD=HIGH,NFR=2,SLEN=28,IVAL=0,ERR=0
12:32:19.155772 usbus3.2 SUBM-CTRL-EP=00000000,SPD=HIGH,NFR=2,SLEN=36,IVAL=0
12:32:19.159264 usbus3.2 
DONE-CTRL-EP=00000000,SPD=HIGH,NFR=2,SLEN=0,IVAL=0,ERR=STALLED
<... at this point webcamd process is ended, but the following lines 
appear after 1-2 secs. Why? ...>
12:32:20.998845 usbus3.2 SUBM-CTRL-EP=00000000,SPD=HIGH,NFR=1,SLEN=8,IVAL=0
12:32:20.999006 usbus3.2 
DONE-CTRL-EP=00000000,SPD=HIGH,NFR=1,SLEN=0,IVAL=0,ERR=0
12:32:20.999019 usbus3.2 SUBM-CTRL-EP=00000000,SPD=HIGH,NFR=1,SLEN=0,IVAL=0
12:32:20.999129 usbus3.2 
DONE-CTRL-EP=00000000,SPD=HIGH,NFR=1,SLEN=0,IVAL=0,ERR=0
12:32:21.011833 usbus3.2 SUBM-CTRL-EP=00000080,SPD=HIGH,NFR=2,SLEN=8,IVAL=0
12:32:21.013626 usbus3.2 
DONE-CTRL-EP=00000080,SPD=HIGH,NFR=2,SLEN=20,IVAL=0,ERR=0
12:32:21.014846 usbus3.2 SUBM-CTRL-EP=00000080,SPD=HIGH,NFR=2,SLEN=8,IVAL=0
12:32:21.016000 usbus3.2 
DONE-CTRL-EP=00000080,SPD=HIGH,NFR=2,SLEN=4,IVAL=0,ERR=0
12:32:21.016014 usbus3.2 SUBM-CTRL-EP=00000080,SPD=HIGH,NFR=2,SLEN=8,IVAL=0
12:32:21.017375 usbus3.2 
DONE-CTRL-EP=00000080,SPD=HIGH,NFR=2,SLEN=4,IVAL=0,ERR=0
12:32:21.017391 usbus3.2 SUBM-CTRL-EP=00000080,SPD=HIGH,NFR=2,SLEN=8,IVAL=0
12:32:21.019250 usbus3.2 
DONE-CTRL-EP=00000080,SPD=HIGH,NFR=2,SLEN=4,IVAL=0,ERR=0
12:32:21.019264 usbus3.2 SUBM-CTRL-EP=00000080,SPD=HIGH,NFR=2,SLEN=8,IVAL=0
12:32:21.021625 usbus3.2 
DONE-CTRL-EP=00000080,SPD=HIGH,NFR=2,SLEN=20,IVAL=0,ERR=0
12:32:21.021644 usbus3.2 SUBM-CTRL-EP=00000080,SPD=HIGH,NFR=2,SLEN=8,IVAL=0
12:32:21.028876 usbus3.2 
DONE-CTRL-EP=00000080,SPD=HIGH,NFR=2,SLEN=12,IVAL=0,ERR=0
12:32:21.028891 usbus3.2 SUBM-CTRL-EP=00000080,SPD=HIGH,NFR=2,SLEN=8,IVAL=0
12:32:21.108758 usbus3.2 
DONE-CTRL-EP=00000080,SPD=HIGH,NFR=2,SLEN=1024,IVAL=0,ERR=0
12:32:21.108773 usbus3.2 SUBM-CTRL-EP=00000080,SPD=HIGH,NFR=2,SLEN=0,IVAL=0
12:32:21.191506 usbus3.2 
DONE-CTRL-EP=00000080,SPD=HIGH,NFR=2,SLEN=1024,IVAL=0,ERR=0
12:32:21.191522 usbus3.2 SUBM-CTRL-EP=00000080,SPD=HIGH,NFR=2,SLEN=0,IVAL=0
12:32:21.273003 usbus3.2 
DONE-CTRL-EP=00000080,SPD=HIGH,NFR=2,SLEN=1024,IVAL=0,ERR=0
12:32:21.273018 usbus3.2 SUBM-CTRL-EP=00000080,SPD=HIGH,NFR=2,SLEN=0,IVAL=0
12:32:21.286251 usbus3.2 
DONE-CTRL-EP=00000080,SPD=HIGH,NFR=2,SLEN=196,IVAL=0,ERR=0
12:32:21.286269 usbus3.2 SUBM-CTRL-EP=00000000,SPD=HIGH,NFR=1,SLEN=8,IVAL=0
12:32:21.286374 usbus3.2 
DONE-CTRL-EP=00000000,SPD=HIGH,NFR=1,SLEN=0,IVAL=0,ERR=0