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We have about 80 systems running ubuntu 12.04 64bit desktop edition. We are facing a strange problem. Everything works fine except that after the monitor goes to sleep, if we don't wake it for long time then it stucks and won't wake up even if we keep pressing any key. But all tty consoles are working. Also i checked the syslog and it was showing the following warning message:

lightdm: pam_ldap: could not open secret file /etc/ldap.secret (No such file or directory)

Also if i pull out the power cable of monitor and insert it back (once the monitor LED goes from orange to black), the screen comes back and this time also the same above message is logged in the syslog. (The message may be totally unrelated to the error but since it was being logged by lightdm i didn't ignore it).

In pm-powersave.log i am getting the following line in the end /usr/lib/pm-utils/power.d/xfs_buffer false: not applicable.

Also sometimes the following message is being also logged kernel: [181899.744014] [drm] GMBUS timed out, falling back to bit banging on pin 6 [i915 gmbus reserved] kernel: [181901.504013] [drm] GMBUS timed out, falling back to bit banging on pin 0 [i915 gmbus disabled] about every 30 minutes.

Could someone please suggest what could be the possible reason for such a behavior.

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It looks like the reason is this GMBUS deadlock problem. Keyboard/Mouse input is not waking up the LCD display. Any solutions of this GMBUS deadlock problem ? – Jatin Kumar Dec 16 '12 at 17:20

I started seeing this same issue when I updated from the regular old Ubuntu 12.04 video driver to 'ATI/AMD proprietary FLGRX graphics driver (post-release updates)'.

I also see

/usr/lib/pm-utils/power.d/xfs_buffer false: not applicable.  
/usr/lib/pm-utils/power.d/disable_wol false: not applicable.

scattered throughout my pm-powersave.log.

I rolled back my video driver to 'ATI/AMD proprietary FLGRX graphics driver' (the release version) and the problem seems to have gone away (in limited testing).

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@Seth: Thanks for the response. I am using Intel i915 driver. But anyway i have applied to changes to revert it back to original package. Lets see if it works. Will get back in some days. – Jatin Kumar Feb 4 '13 at 14:27

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