entering encryption password not possible at boot

[a.l]

Entering the encryption password at boot is not possible. Keyboard input is not accepted. Repeatable.

workaround: reboot (hardware key shutdown & on)
  Grub --> -Advanced options for Ubuntu (in german: erweiterte Optionen für Ubuntu), enter --> recovery mode, enter --> enter password --> recovery menu: resume
  --> Boot OK but compiz causes high CPU load in Unity
  --> reboot again
  --> distorted password screen appears which accepts password --> Boot & compiz OK

config
 Ubuntu 14.10 64 bit
 MacBook Air 3,2 late 2010
 lvm / full disk encryption
 only ubuntu installed

$apt-cache policy cryptsetup
cryptsetup:
  Installed: 2:1.6.1-1ubuntu3
  Candidate: 2:1.6.1-1ubuntu3
  Version table:
 *** 2:1.6.1-1ubuntu3 0
        500 http://de.archive.ubuntu.com/ubuntu/ utopic/main amd64 Packages
        100 /var/lib/dpkg/status

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.