A pre-configured Raring 13.94 image with the 3.11 kernel seems to be very unstable with my DVI monitor. Depending on some boot timing, it may not recognize the monitor at all, or it may recognize it correctly, and work with it.
Sometimes the EDID info can be read:
# parse-edid /sys/class/drm/card1-Unknown-1/edid
parse-edid: parse-edid version 2.0.0
parse-edid: EDID checksum passed.
# EDID version 1 revision 3
Section "Monitor"
# Block type: 2:0 3:fd
# Block type: 2:0 3:ff
# Block type: 2:0 3:fc
Identifier "Acer S231HL"
VendorName "ACR"
ModelName "Acer S231HL"
# Block type: 2:0 3:fd
HorizSync 30-80
VertRefresh 55-75
# Max dot clock (video bandwidth) 160 MHz
# Block type: 2:0 3:ff
# Block type: 2:0 3:fc
# DPMS capabilities: Active off:yes Suspend:no Standby:no
Mode "1920x1080" # vfreq 60.000Hz, hfreq 67.500kHz
DotClock 148.500000
HTimings 1920 2008 2052 2200
VTimings 1080 1084 1089 1125
Flags "+HSync" "+VSync"
EndMode
# Block type: 2:0 3:fd
# Block type: 2:0 3:ff
# Block type: 2:0 3:fc
EndSection
Sometimes the EDID info "cannot be read":
# parse-edid /sys/class/drm/card1-Unknown-1/edid
parse-edid: parse-edid version 2.0.0
parse-edid: IO error reading EDID
When this happens, the monitor no longer shows anything at all. If I re-plug the DVI cable, the picture sometimes shows up after a couple of seconds, and then a couple of seconds later goes away. Seems that EDID reading has become unstable.
I rebuilt the 3.11 kernel with the latest patches, no difference.
When the monitor is connected via a KVM switch, the resolution is sometimes lower than with the direct connection. And the same thing often happens: after a couple of seconds the picture disappears.
On 3.7 I never saw anything like this. Would have stayed on 3.7 for now, which seems to be more stable, but I the 3.11 has some USB EHCI fixes to enable support for the KVM switch.
Thanks!