usb/140810: 8.X+ uftdi copy and paste problem / tty overflow

Hans Petter Selasky hselasky at c2i.net
Mon Nov 23 20:59:46 UTC 2009 

On Monday 23 November 2009 19:59:56 Corey Smith wrote:
> On Mon, 2009-11-23 at 11:25 -0500, Hans Petter Selasky wrote:
> > sysctl hw.usb.ucom.debug=15
>
> Thanks for the quick reply.  I decided to do a fresh install of
> 8.0-RELEASE amd64 before I re-ran the test.  Here are the details:
>
> # uname -a
> FreeBSD lab1 8.0-RELEASE FreeBSD 8.0-RELEASE #0: Sat Nov 21 15:02:08 UTC
> 2009     root at mason.cse.buffalo.edu:/usr/obj/usr/src/sys/GENERIC  amd64 #
> sysctl hw.usb.ucom.debug=15
> # tip ucom1
> connected
> # paste 160 "a"s followed by a newline (may take several attempts when
> debugging is enabled)
> aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
>aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
>aaaaaaaa
>
> Nov 23 14:54:13 lab1 su: csmith to root on /dev/pts/0
> Nov 23 14:57:14 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:14 lab1 kernel: ucom_get_data:1064: cnt=1
> Nov 23 14:57:14 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:14 lab1 kernel: ucom_get_data:1064: cnt=1
> Nov 23 14:57:14 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:14 lab1 kernel: ucom_get_data:1064: cnt=1
> Nov 23 14:57:14 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:14 lab1 kernel: ucom_get_data:1064: cnt=1
> Nov 23 14:57:14 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:14 lab1 kernel: ucom_get_data:1064: cnt=1
> Nov 23 14:57:14 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:14 lab1 kernel: ucom_get_data:1064: cnt=1
> Nov 23 14:57:14 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:14 lab1 kernel: ucom_get_data:1064: cnt=1
> Nov 23 14:57:14 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:14 lab1 kernel: ucom_get_data:1064: cnt=1
> Nov 23 14:57:14 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:14 lab1 kernel: ucom_get_data:1064: cnt=1
> Nov 23 14:57:14 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:14 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:14 lab1 kernel: ucom_get_data:1064: cnt=2
> Nov 23 14:57:14 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:14 lab1 last message repeated 2 times
> Nov 23 14:57:14 lab1 kernel: ucom_get_data:1064: cnt=3
> Nov 23 14:57:14 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:14 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:14 lab1 kernel: ucom_get_data:1064: cnt=2
> Nov 23 14:57:14 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:14 lab1 last message repeated 4 times
> Nov 23 14:57:14 lab1 kernel: ucom_get_data:1064: cnt=5
> Nov 23 14:57:14 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:14 lab1 last message repeated 8 times
> Nov 23 14:57:14 lab1 kernel: ucom_get_data:1064: cnt=9
> Nov 23 14:57:14 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:14 lab1 last message repeated 4 times
> Nov 23 14:57:14 lab1 kernel: ucom_get_data:1064: cnt=5
> Nov 23 14:57:14 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:14 lab1 last message repeated 13 times
> Nov 23 14:57:14 lab1 kernel: ucom_get_data:1064: cnt=13
> Nov 23 14:57:14 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:14 lab1 last message repeated 26 times
> Nov 23 14:57:14 lab1 kernel: ucom_get_data:1064: cnt=27
> Nov 23 14:57:14 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:14 lab1 last message repeated 14 times
> Nov 23 14:57:14 lab1 kernel: ucom_get_data:1064: cnt=15
> Nov 23 14:57:14 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:14 lab1 last message repeated 37 times
> Nov 23 14:57:14 lab1 kernel: ucom_get_data:1064: cnt=37
> Nov 23 14:57:14 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:14 lab1 last message repeated 34 times
> Nov 23 14:57:14 lab1 kernel: ucom_get_data:1064: cnt=33
> Nov 23 14:57:14 lab1 kernel: ucom_get_data:1064: cnt=0
> Nov 23 14:57:15 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:15 lab1 kernel: ucom_get_data:1064: cnt=1
> Nov 23 14:57:15 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:15 lab1 kernel: ucom_get_data:1064: cnt=1
> Nov 23 14:57:15 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:15 lab1 kernel: ucom_get_data:1064: cnt=1
> Nov 23 14:57:15 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:15 lab1 kernel: ucom_get_data:1064: cnt=1
> Nov 23 14:57:15 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:15 lab1 kernel: ucom_get_data:1064: cnt=1
> Nov 23 14:57:15 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:15 lab1 kernel: ucom_get_data:1064: cnt=1
> Nov 23 14:57:15 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:15 lab1 kernel: ucom_get_data:1064: cnt=1
> Nov 23 14:57:15 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:15 lab1 kernel: ucom_get_data:1064: cnt=1
> Nov 23 14:57:15 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:15 lab1 kernel: ucom_get_data:1064: cnt=1
> Nov 23 14:57:15 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:15 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:15 lab1 kernel: ucom_get_data:1064: cnt=2
> Nov 23 14:57:15 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:15 lab1 last message repeated 2 times
> Nov 23 14:57:15 lab1 kernel: ucom_get_data:1064: cnt=3
> Nov 23 14:57:15 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:15 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:15 lab1 kernel: ucom_get_data:1064: cnt=2
> Nov 23 14:57:15 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:15 lab1 last message repeated 4 times
> Nov 23 14:57:15 lab1 kernel: ucom_get_data:1064: cnt=5
> Nov 23 14:57:15 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:15 lab1 last message repeated 8 times
> Nov 23 14:57:15 lab1 kernel: ucom_get_data:1064: cnt=9
> Nov 23 14:57:15 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:15 lab1 last message repeated 4 times
> Nov 23 14:57:15 lab1 kernel: ucom_get_data:1064: cnt=5
> Nov 23 14:57:15 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:15 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:15 lab1 kernel:
> Nov 23 14:57:15 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:15 lab1 last message repeated 3 times
> Nov 23 14:57:15 lab1 kernel:
> Nov 23 14:57:15 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:15 lab1 kernel:
> Nov 23 14:57:15 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:15 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:15 lab1 kernel:
> Nov 23 14:57:15 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:15 lab1 kernel:
> Nov 23 14:57:15 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:15 lab1 last message repeated 3 times
> Nov 23 14:57:15 lab1 kernel: ucom_get_data:1064: cnt=14
> Nov 23 14:57:15 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:15 lab1 last message repeated 14 times
> Nov 23 14:57:15 lab1 kernel:
> Nov 23 14:57:15 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:15 lab1 last message repeated 9 times
> Nov 23 14:57:15 lab1 kernel:
> Nov 23 14:57:15 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:15 lab1 kernel:
> Nov 23 14:57:15 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:15 lab1 kernel: ucom_get_data:1064: cnt=26
> Nov 23 14:57:15 lab1 kernel:
> Nov 23 14:57:15 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:15 lab1 last message repeated 14 times
> Nov 23 14:57:15 lab1 kernel: ucom_get_data:1064: cnt=15
> Nov 23 14:57:15 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:15 lab1 last message repeated 11 times
> Nov 23 14:57:15 lab1 kernel:
> Nov 23 14:57:15 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:15 lab1 last message repeated 5 times
> Nov 23 14:57:15 lab1 kernel:
> Nov 23 14:57:15 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:15 lab1 kernel:
> Nov 23 14:57:15 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:15 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:15 lab1 kernel:
> Nov 23 14:57:15 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:15 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:15 lab1 kernel:
> Nov 23 14:57:15 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:15 lab1 last message repeated 12 times
> Nov 23 14:57:15 lab1 kernel:
> Nov 23 14:57:15 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:15 lab1 last message repeated 5 times
> Nov 23 14:57:15 lab1 kernel: ucom_get_data:1064: cnt=41
> Nov 23 14:57:15 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:15 lab1 last message repeated 17 times
> Nov 23 14:57:15 lab1 kernel:
> Nov 23 14:57:15 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:15 lab1 last message repeated 12 times
> Nov 23 14:57:15 lab1 kernel: ucom_get_data:1064: cnt=29
> Nov 23 14:57:15 lab1 kernel: ucom_get_data:1064: cnt=0
> Nov 23 14:57:16 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:16 lab1 kernel: ucom_get_data:1064: cnt=1
> Nov 23 14:57:16 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:16 lab1 kernel: ucom_get_data:1064: cnt=1
> Nov 23 14:57:16 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:16 lab1 kernel: ucom_get_data:1064: cnt=1
> Nov 23 14:57:16 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:16 lab1 kernel: ucom_get_data:1064: cnt=1
> Nov 23 14:57:16 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:16 lab1 kernel: ucom_get_data:1064: cnt=1
> Nov 23 14:57:16 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:16 lab1 kernel: ucom_get_data:1064: cnt=1
> Nov 23 14:57:16 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:16 lab1 kernel: ucom_get_data:1064: cnt=1
> Nov 23 14:57:16 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:16 lab1 kernel: ucom_get_data:1064: cnt=1
> Nov 23 14:57:16 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:16 lab1 kernel: ucom_get_data:1064: cnt=1
> Nov 23 14:57:16 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:16 lab1 last message repeated 2 times
> Nov 23 14:57:16 lab1 kernel: ucom_get_data:1064: cnt=3
> Nov 23 14:57:16 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:16 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:16 lab1 kernel: ucom_get_data:1064: cnt=2
> Nov 23 14:57:16 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:16 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:16 lab1 kernel: ucom_get_data:1064: cnt=2
> Nov 23 14:57:16 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:16 lab1 last message repeated 7 times
> Nov 23 14:57:16 lab1 kernel: ucom_get_data:1064: cnt=8
> Nov 23 14:57:16 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:16 lab1 last message repeated 5 times
> Nov 23 14:57:16 lab1 kernel: ucom_get_data:1064: cnt=6
> Nov 23 14:57:16 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:16 lab1 last message repeated 4 times
> Nov 23 14:57:16 lab1 kernel: ucom_get_data:1064: cnt=5
> Nov 23 14:57:16 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:16 lab1 last message repeated 23 times
> Nov 23 14:57:16 lab1 kernel: ucom_get_data:1064: cnt=23
> Nov 23 14:57:16 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:16 lab1 last message repeated 16 times
> Nov 23 14:57:16 lab1 kernel: ucom_get_data:1064: cnt=17
> Nov 23 14:57:16 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:16 lab1 last message repeated 14 times
> Nov 23 14:57:16 lab1 kernel: ucom_get_data:1064: cnt=15
> Nov 23 14:57:16 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:16 lab1 last message repeated 68 times
> Nov 23 14:57:16 lab1 kernel: ucom_get_data:1064: cnt=64
> Nov 23 14:57:16 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:16 lab1 last message repeated 4 times
> Nov 23 14:57:16 lab1 kernel: ucom_get_data:1064: cnt=6
> Nov 23 14:57:16 lab1 kernel: ucom_get_data:1064: cnt=0
> Nov 23 14:57:18 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:18 lab1 kernel: ucom_get_data:1064: cnt=1
> Nov 23 14:57:18 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:18 lab1 last message repeated 135 times
> Nov 23 14:57:18 lab1 kernel:
> Nov 23 14:57:18 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:18 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:18 lab1 kernel:
> Nov 23 14:57:18 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:18 lab1 last message repeated 9 times
> Nov 23 14:57:18 lab1 kernel:
> Nov 23 14:57:18 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:18 lab1 kernel:
> Nov 23 14:57:18 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:18 lab1 kernel:
> Nov 23 14:57:18 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:18 lab1 last message repeated 3 times
> Nov 23 14:57:18 lab1 kernel:
> Nov 23 14:57:18 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:18 lab1 kernel:
> Nov 23 14:57:18 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:18 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:18 lab1 kernel:
> Nov 23 14:57:18 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:18 lab1 kernel:
> Nov 23 14:57:18 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:39 lab1 last message repeated 1307 times
> Nov 23 14:57:39 lab1 kernel:
> Nov 23 14:57:39 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:42 lab1 last message repeated 212 times
> Nov 23 14:57:43 lab1 kernel:
> Nov 23 14:57:43 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:45 lab1 last message repeated 187 times
> Nov 23 14:57:46 lab1 kernel:
> Nov 23 14:57:46 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:57:58 lab1 last message repeated 801 times
> Nov 23 14:57:58 lab1 kernel:
> Nov 23 14:57:58 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:58:29 lab1 last message repeated 1891 times
> Nov 23 14:58:29 lab1 last message repeated 50 times
> Nov 23 14:58:29 lab1 kernel:
> Nov 23 14:58:29 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:58:55 lab1 last message repeated 1640 times
> Nov 23 14:58:56 lab1 kernel:
> Nov 23 14:58:56 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:59:27 lab1 last message repeated 1940 times
> Nov 23 14:59:43 lab1 last message repeated 1051 times
> Nov 23 14:59:43 lab1 kernel:
> Nov 23 14:59:43 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 14:59:57 lab1 last message repeated 825 times
> Nov 23 14:59:57 lab1 kernel:
> Nov 23 14:59:57 lab1 kernel: ucom_outwakeup:1009: sc = 0xffffff0003052858
> Nov 23 15:00:00 lab1 newsyslog[926]: logfile turned over due to size>100K
> Nov 23 15:00:00 lab1 last message repeated 208 times
>
> I believe the problem occurs whenever you see a message like this:
> Nov 23 14:57:16 lab1 kernel: ucom_get_data:1064: cnt=64
>
> >From a look at the code it looks like the largest uftdi frame is 64
> > characters (UFTDI_[IO]BUFSIZE in uftdi.c).  Perhaps it is an off by one
> > bug?
>
> -Corey Smith

Hi,

Your issue looks like a hardware issue. Does the following patch help?

==== //depot/projects/usb/src/sys/dev/usb/serial/uftdi.c#16 - 
src/sys/dev/usb/serial/uftdi.c ====
@@ -165,7 +165,7 @@
                .endpoint = UE_ADDR_ANY,
                .direction = UE_DIR_OUT,
                .bufsize = UFTDI_OBUFSIZE,
-               .flags = {.pipe_bof = 1,.force_short_xfer = 1,},
+               .flags = {.pipe_bof = 1,},
                .callback = &uftdi_write_callback,
        },

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