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Bug 112889

Summary: usb<->rs-232 converter prints only garbage
Product: [Retired] Red Hat Raw Hide Reporter: Kaj J. Niemi <kajtzu>
Component: kernelAssignee: Pete Zaitcev <zaitcev>
Status: CLOSED RAWHIDE QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: 1.0   
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Hardware: All   
OS: Linux   
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Fixed In Version: Doc Type: Bug Fix
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Clone Of: Environment:
Last Closed: 2004-03-10 06:31:19 UTC Type: ---
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Description Flags
Test fix 2 none

Description Kaj J. Niemi 2004-01-05 13:53:35 UTC 
With kernel-2.6.0-1.23 a Magic Controller Technology USB<->RS-232
converter prints only garbage to the screen when connected to any
RS-232 equipment at any bit rate. The equipment at the other end of
the cable is known good and works.

Setserial /dev/ttyUSBS0 returns invalid argument.

Description of problem:
Jan  5 14:55:48 d120 kernel: hub 3-0:1.0: new USB device on port 2,
assigned address 2
Jan  5 14:55:49 d120 kernel: drivers/usb/serial/usb-serial.c: USB
Serial support registered for Generic
Jan  5 14:55:49 d120 kernel: drivers/usb/core/usb.c: registered new
driver usbserial
Jan  5 14:55:49 d120 kernel: drivers/usb/serial/usb-serial.c: USB
Serial Driver core v2.0
Jan  5 14:55:49 d120 kernel: drivers/usb/serial/usb-serial.c: USB
Serial support registered for Magic Control Technology USB-RS232
Jan  5 14:55:49 d120 kernel: mct_u232 3-2:1.0: Magic Control
Technology USB-RS232 converter detected
Jan  5 14:55:49 d120 kernel: usb 3-2: Magic Control Technology
USB-RS232 converter now attached to ttyUSB0 (or usb/tts/0 for devfs)
Jan  5 14:55:49 d120 kernel: drivers/usb/core/usb.c: registered new
driver mct_u232
Jan  5 14:55:49 d120 kernel: drivers/usb/serial/mct_u232.c: Magic
Control Technology USB-RS232 converter driver v1.2
Jan  5 14:55:49 d120 devlabel: devlabel service started/restarted

Version-Release number of selected component (if applicable):
kernel-2.6.0-1.23

How reproducible:
Always

Steps to Reproduce:
1. plug usb-serial converter
2. minicom
3. wait

Actual Results:  Prints garbage at any bit rate

Expected Results:  Echo something sane to the screen

Additional info:
Any thoughts?
Comment 1 Kaj J. Niemi 2004-01-16 17:18:37 UTC 
Still a problem with kernel-2.6.0-1.43
Comment 2 Kaj J. Niemi 2004-01-16 17:18:51 UTC 
Uh that would be 2.6.1-1.43 :)
Comment 3 Pete Zaitcev 2004-01-18 08:37:35 UTC 
I only saw it on 9600. 38400 works fine. The driver is made
out of reverse-engineered snooper traces, so I'm not surprised
it gets divisors wrong somewhere.

The setserial is not supported in most of USB serial sub-drivers.
But it's beside the point here.
Comment 4 Kaj J. Niemi 2004-01-18 13:54:40 UTC 
O-kay! is there anything I can do to help you out to fix this or would
you like to suggest another, known working, usb <-> rs232 converter?
Most console applications I use (Cisco routers/switches and Sun
servers) talk back at 9600 8N1. The Wise People over at International
Banana Machines decided to leave a standard 9-pin serial port out of
the Thinkpad T40p.

Wasn't aware of setserial not working on usb.
Comment 5 Pete Zaitcev 2004-01-20 01:55:08 UTC 
Created attachment 97119 [details]
Test fix 2
Comment 6 Pete Zaitcev 2004-01-20 01:58:33 UTC 
9600 is the victim, because it's the default speed after reboots.
It can fail to set 38400 as well, in the following scenario:

Run equipment on 38400.
Connect adapter.
Start kermit / minicom.
Disconnect (at this point, MCT structures are gone, but tty stays!)
Quit kermit / minicom.
Reconnect.
Start kermit / minicom again;
 -- at open time, wrong comparison prevents settings to be set
Comment 7 Kaj J. Niemi 2004-01-20 10:35:06 UTC 
Work at 9600 8N1 now as well. Tested it against Cisco equipment.
Comment 8 Kaj J. Niemi 2004-01-28 19:02:07 UTC 
I noticed one more thing... sending break from minicom doesn't work
(while it does using the same cable on another laptop connected to a
normal com-port). Should I file another bug? This is with 2.6.1-1.57.
Comment 9 Pete Zaitcev 2004-01-28 19:24:15 UTC 
Please go ahead and file.

There's quite a bit of functions which either usbserial or
various component drivers do not implement at all. I have
about two bugs about it already. I'll get back to it when I can.
Comment 10 Pete Zaitcev 2004-03-09 23:12:04 UTC 
Can this be closed?
Comment 11 Kaj J. Niemi 2004-03-10 06:31:19 UTC 
Yeah, this can be closed. Thanks.