kern/49115: serial interface (/dev/tty*) not working

[n54%gmx.com@localhost]

>Number:         49115
>Category:       kern
>Synopsis:       serial interface (/dev/tty*) not working
>Confidential:   no
>Severity:       critical
>Priority:       high
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Thu Aug 14 17:15:00 +0000 2014
>Originator:     Kamil Rytarowski
>Release:        NetBSD-current, NetBSD-6.1.x
>Organization:
>Environment:
NetBSD, amd64
current (pre 7.0) and stable 6.1.x
>Description:
I cannot get serial connector to work on different amd64 machines.

minicom -b 115200 -D /dev/ttyU0
picocom -b 115200 /dev/ttyU0
cu -s 115200 -l /dev/ttyU0

I was trying with an USB-serial adapter.

dmesg:
uchcom0 at uhub6 port 1
uchcom0: QinHeng Electronics USB2.0-Ser!, rev 1.10/2.54, addr 2
uchcom0: CH341 detected
ucom0 at uchcom0

I was trying with a PCI card with two serial connectors (and relevant /dev/tty0 
device), without success.

I was testing my embedded machine with serial and the peripherals under 
GNU/Linux and the device worked.

Here is a log with a working options from GNU/Linux:

picocom v1.6

port is : /dev/ttyUSB0
flowcontrol : none
baudrate is : 115200
parity is : none
databits are : 8
escape is : C-a
local echo is : no
noinit is : no
noreset is : no
nolock is : no
send_cmd is : sz -vv
receive_cmd is : rz -vv
imap is :
omap is :
emap is : crcrlf,delbs,

Reproducing it on NetBSD results at best with detaching ucom (and /dev/ttyU0) 
from drvlst.

Once I was trying to connect to a different device with USB-TTL connector, 
without any luck.
>How-To-Repeat:
1. Install NetBSD-6.1.x or current.
2. Get a PCI RS232 card or USB adapter with RS242 port
3. Get a third party machine designed to work through serial
4. Connect cables, power on
5. Try cu, picocom, minicom to establish a connection
6. Read none characters from the device.
>Fix:
Get Linux and see that the peripherals work.