FTDI USB serial FT232RL regression, requires toggling flow control

After restarting yesterday (after +/-23 days), the Linux kernel updates got effective and rendered my USB serial ports unusable until I toggled the flow control off and then on again. Before the update I could use my serial ports without problems at 460800 baud, with flow control. I normally use my cross-platform application to access the serial port, but the problem is also visible with socat.

I do get bytes over the serial port but I cannot believe that it is correct:

$ socat /dev/ttyUSB0,nonblock,crtscts=1,cs8,cstopb=1,echo=0,b460800 -|hexdump -C

00000000 c0 00 c0 c0 00 e0 00 e0 e0 c0 00 00 00 00 c0 e0 |................|
00000010 e0 00 00 00 00 c0 00 e0 00 00 00 00 00 c0 00 e0 |................|
00000020 c0 00 c0 00 c0 00 00 00 00 00 00 00 00 c0 00 e0 |................|
00000030 00 c0 e0 00 c0 00 c0 c0 00 e0 00 c0 00 00 c0 e0 |................|
00000040 c0 e0 00 c0 e0 00 00 c0 c0 c0 c0 00 e0 00 00 c0 |................|

After toggling the flow_control off, I get (serial messages start with 01 2f):

$ socat /dev/ttyUSB0,nonblock,crtscts=0,cs8,cstopb=1,echo=0,b460800 -|hexdump -C
00000000 00 00 00 00 00 e0 00 c0 c0 e0 c0 00 00 e0 00 e0 |................|
00000010 c0 00 c0 00 00 00 c0 00 c0 c0 e0 c0 c0 00 e0 00 |................|
00000020 e0 c0 00 00 c0 00 00 c0 c0 c0 e0 00 c0 c0 00 00 |................|
00000030 e0 c0 e0 00 c0 00 e0 c0 00 e0 00 00 c0 00 00 00 |................|
00000040 c0 00 c0 c0 00 00 c0 e0 c0 00 00 c0 00 b2 ff d5 |................|
00000050 ff c2 00 16 ff fd 0e 0a ff fc ff ff fe a6 ff be |................|
00000060 00 18 ff fd a7 03 01 2f 03 77 22 00 ff ff 01 08 |......./.w".....|
00000070 28 21 00 00 0c 56 ff fd 26 1a 0a ff ec ff dc fe |(!...V..&.......|
00000080 a6 ff c1 00 20 00 31 ff f6 00 09 fe a7 ff bf 00 |.... .1.........|
00000090 25 00 1b 14 0e ff f4 ff fa fe a4 01 4a 00 1c ff |%...........J...|
000000a0 78 ff c6 00 1e 00 12 26 0a 00 02 ff fc fe ab ff |x......&........|

After toggling flow_control back on, I get:

$ socat /dev/ttyUSB0,nonblock,crtscts=1,cs8,cstopb=1,echo=0,b460800 -|hexdump -C
00000000 01 2f 03 6f 22 00 ff ff 01 08 28 21 00 00 54 01 |./.o".....(!..T.|
00000010 00 00 26 26 0a ff fc ff fe fe a7 ff c1 00 1a ff |..&&............|
00000020 ff ff fc ff fd fe a7 ff bf 00 1a ff fd ff fd ff |................|
00000030 fe fe a7 ff c0 00 1a ff ff 14 0e ff fc ff fe fe |................|
00000040 a6 ff ec 00 09 00 4e ff c0 00 17 ff ff 26 0a ff |......N......&..|
00000050 fd ff ff fe a5 ff be 00 1a ff fb ff fc ff ff fe |................|
00000060 a4 ff be 00 19 00 01 ff fc ff fe fe a5 ff be 00 |................|

After this procedure, I can succesfully use the device and stop/start the serial communication, until I unplug it. After unplugging or plugging in another device with the same FTDI chip, I have to toggle flow_control again to get it to work.

I also used the fired up VirtualBox with Windows-XP and had no trouble connecting getting the right data from the serial port (e.g. in putty, terraterm, my own cross-platform application, no flow_control toggling required), also using switching between FTDI devices didnt' give any problems.

ProblemType: Bug
DistroRelease: Ubuntu 11.10
Package: linux-image-3.0.0-15-generic 3.0.0-15.26
ProcVersionSignature: Ubuntu 3.0.0-15.26-generic 3.0.13
Uname: Linux 3.0.0-15-generic x86_64
AlsaVersion: Advanced Linux Sound Architecture Driver Version 1.0.24.
AplayDevices:
 **** List of PLAYBACK Hardware Devices ****
 card 0: Intel [HDA Intel], device 0: STAC92xx Analog [STAC92xx Analog]
   Subdevices: 1/1
   Subdevice #0: subdevice #0
ApportVersion: 1.23-0ubuntu4
Architecture: amd64
ArecordDevices:
 **** List of CAPTURE Hardware Devices ****
 card 0: Intel [HDA Intel], device 0: STAC92xx Analog [STAC92xx Analog]
   Subdevices: 1/1
   Subdevice #0: subdevice #0
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: bijwaard 1736 F.... pulseaudio
CRDA: Error: [Errno 2] No such file or directory
Card0.Amixer.info:
 Card hw:0 'Intel'/'HDA Intel at 0xe8604000 irq 47'
   Mixer name : 'IDT 92HD75B2X5'
   Components : 'HDA:111d7608,103c308a,00100202 HDA:11c11040,103c1378,00100200'
   Controls : 14
   Simple ctrls : 9
Date: Tue Jan 24 13:10:01 2012
HibernationDevice: RESUME=UUID=32c975b3-5e3a-4d0b-8cdc-d81ec4c4a02e
InstallationMedia: Xubuntu 11.10 "Oneiric Ocelot" - Release amd64 (20111012)
MachineType: Hewlett-Packard Compaq 610
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.0.0-15-generic root=UUID=cb9e7103-08de-46ee-975b-7eef245d4041 ro quiet splash vt.handoff=7
RelatedPackageVersions:
 linux-restricted-modules-3.0.0-15-generic N/A
 linux-backports-modules-3.0.0-15-generic N/A
 linux-firmware 1.60
SourcePackage: linux
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 12/17/2009
dmi.bios.vendor: Hewlett-Packard
dmi.bios.version: 68PVU Ver. F.0D
dmi.board.name: 308A
dmi.board.vendor: Hewlett-Packard
dmi.board.version: KBC Version 26.08
dmi.chassis.asset.tag: CNU0064GLG
dmi.chassis.type: 10
dmi.chassis.vendor: Hewlett-Packard
dmi.modalias: dmi:bvnHewlett-Packard:bvr68PVUVer.F.0D:bd12/17/2009:svnHewlett-Packard:pnCompaq610:pvrF.0D:rvnHewlett-Packard:rn308A:rvrKBCVersion26.08:cvnHewlett-Packard:ct10:cvr:
dmi.product.name: Compaq 610
dmi.product.version: F.0D
dmi.sys.vendor: Hewlett-Packard