Follow up : the flicker lowered in intensity during the week end. It came back after the first stand-by mode.
I found that bug #761065 maybe somewhat related, but I'm not sure. I just tried the proposed workaround, i.e. set /sys/module/i915/parameters/semaphores to "1", using the following kernel option in /etc/default/grub GRUB_CMDLINE_LINUX_DEFAULT="quiet splash i915.semaphores=1" (again, I suspect i915 is the correct module for sandy bridge HD 3000, but I'm not sure). After running update-grub and rebooting, I still had flickering but the amplitude of the flicker is different depending on the screen zone (roughly 2/3 left : lower flicker, 1/3 right : same amplitude flicker). Also there is a problem in the screen size calculation (part of my external monitor is duplicated on the laptop's screen) : $ xrandr -q Screen 0: minimum 320 x 200, current 3280 x 1080, maximum 8192 x 8192 LVDS1 connected 1600x900+0+0 (normal left inverted right x axis y axis) 310mm x 174mm 1600x900 60.0*+ 40.0 1440x900 59.9 1360x768 59.8 60.0 1152x864 60.0 1024x768 60.0 800x600 60.3 56.2 640x480 59.9 VGA1 disconnected (normal left inverted right x axis y axis) HDMI1 disconnected (normal left inverted right x axis y axis) DP1 disconnected (normal left inverted right x axis y axis) HDMI2 disconnected (normal left inverted right x axis y axis) HDMI3 connected 1920x1080+1360+0 (normal left inverted right x axis y axis) 531mm x 298mm 1920x1080 59.9*+ 1600x1200 60.0 1680x1050 60.0 1280x1024 60.0 1440x900 59.9 1280x960 60.0 1280x800 59.8 1024x768 60.0 800x600 60.3 56.2 640x480 60.0 DP2 disconnected (normal left inverted right x axis y axis) DP3 disconnected (normal left inverted right x axis y axis) Screen has 3280 pixel width, where I should have 1600 + 1920 = 3520 pixels.... Looks like the driver thinks I have a 1360x768 laptop screen. .config/monitors.xml has the correct size (<width>1600</width><height>900</height>). Weird... -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/794474 Title: latitude e6420 screen flickering (sandy bridge intel video card) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/xserver-xorg-video-intel/+bug/794474/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
