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[Bug 1542862] Re: pl2303h and ftdi serial port bug


** Tags added: xenial

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  pl2303h and ftdi serial port bug

Status in linux package in Ubuntu:

Bug description:
  When developing an application using serial ports, behaviour between
  process restarts is undefined for particular usb serial port chipsets.

  Tested chipsets to fail are:
  * pl2303H
  * ftdi

  Tested chipsets to work are:
  * 16550A
  * pl2303ra

  Attached is a minimal test program to recreate the issue. The program
  needs to run twice, the first to create the problem, the second
  instance that shows the problem. See the comments at the beginning of
  the test program to see expected output and observed output.

  You'll need the device under question attached and running as the
  receiver in the test program and a NULL modem cable (3 wire). Easiest
  to show the problem if you have two of the same USB devices attached
  and execute the command with "./a.out /dev/ttyUSB0 /dev/ttyUSB1".

  Note, flushing, and other workarounds haven't worked, only physically
  removing and reinserting the problematic devices between runs (in
  particular, the device that is receiving the data over the serial

  As there appears to be data in a buffer between runs that can't be
  properly flushed, I can't say if this is a potential security issue or

  ProblemType: Bug
  DistroRelease: Ubuntu 14.04
  Package: linux-image-3.19.0-49-generic 3.19.0-49.55~14.04.1
  ProcVersionSignature: Ubuntu 3.19.0-49.55~14.04.1-generic 3.19.8-ckt12
  Uname: Linux 3.19.0-49-generic i686
  ApportVersion: 2.14.1-0ubuntu3.19
  Architecture: i386
  CurrentDesktop: Unity
  Date: Sun Feb  7 15:28:42 2016
  InstallationDate: Installed on 2016-02-04 (2 days ago)

  SourcePackage: linux-lts-vivid
  UpgradeStatus: No upgrade log present (probably fresh install)
  ApportVersion: 2.14.1-0ubuntu3.19
  Architecture: i386
   /dev/snd/controlC0:  jcurl      2149 F.... pulseaudio
  CurrentDesktop: Unity
  DistroRelease: Ubuntu 14.04
  HibernationDevice: RESUME=UUID=f20d2ed2-18be-4b14-b4f2-d28d8962a377
  InstallationDate: Installed on 2016-02-04 (31 days ago)
  MachineType: LENOVO 64577WG
  NonfreeKernelModules: nvidia
  Package: linux (not installed)
   Socket 0:
     no product info available
   Socket 0:
    PC Card
  ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.19.0-49-generic root=UUID=77ac576d-595e-4ec1-ae5e-3791f7cfe23b ro quiet splash
  ProcVersionSignature: Ubuntu 3.19.0-49.55~14.04.1-generic 3.19.8-ckt12
   linux-restricted-modules-3.19.0-49-generic N/A
   linux-backports-modules-3.19.0-49-generic  N/A
   linux-firmware                             1.127.20
  Tags:  trusty
  Uname: Linux 3.19.0-49-generic i686
  UpgradeStatus: No upgrade log present (probably fresh install)
  UserGroups: adm cdrom dip lpadmin plugdev sambashare sudo
  _MarkForUpload: True
  dmi.bios.date: 04/08/2010
  dmi.bios.vendor: LENOVO
  dmi.bios.version: 7LETC7WW (2.27 )
  dmi.board.name: 64577WG
  dmi.board.vendor: LENOVO
  dmi.board.version: Not Available
  dmi.chassis.asset.tag: No Asset Information
  dmi.chassis.type: 10
  dmi.chassis.vendor: LENOVO
  dmi.chassis.version: Not Available
  dmi.modalias: dmi:bvnLENOVO:bvr7LETC7WW(2.27):bd04/08/2010:svnLENOVO:pn64577WG:pvrThinkPadT61p:rvnLENOVO:rn64577WG:rvrNotAvailable:cvnLENOVO:ct10:cvrNotAvailable:
  dmi.product.name: 64577WG
  dmi.product.version: ThinkPad T61p
  dmi.sys.vendor: LENOVO

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