Since some days I'm having the following issue. When system try to start X to run lightdm it fails, the displayed window says that the system seems unable to recognize all the devices, after that it ask me what I want to do. The funny part in all this is that if I log in tty, kill xinit and give the command
service lightdm start
it works: the it loads the login screen and after that I can work fine.
From the log in /var/log/Xorg.failsafe.log the only error seems to be
(EE) FBDEV(0): FBIOPUTCMAP: Invalid argument
The distro I'm using is an ubuntu 12.04 my graphic card is a ATI RV710.
Does anyone have idea on what the problem could be? And what does it mean the error in log above?