I see this same issue in 11.10 with the Intel GM45 chipset and a docking station.
Screensaver kicks in and turns off the monitor and it never comes back. I have to switch to a VT and restart lightdm. I see the drm:drm_edid_block_valid error in dmesg.
The 'echo 0 > /sys/module/drm_kms_helper/parameters/poll' workaround resolves the issue.
I see this same issue in 11.10 with the Intel GM45 chipset and a docking station.
Screensaver kicks in and turns off the monitor and it never comes back. I have to switch to a VT and restart lightdm. I see the drm:drm_ edid_block_ valid error in dmesg.
The 'echo 0 > /sys/module/ drm_kms_ helper/ parameters/ poll' workaround resolves the issue.