After some research I found errors related to i915 module (see some output attached).
I tried some kernel module parameters without success, but the solution that seems to work for me is disabling of SNA acceleration-backend following: https://wiki.archlinux.org/index.php/Intel_graphics#SNA_issues Would be great, if someone could confirm. ** Attachment added: "sleep_err_output.txt" https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1301601/+attachment/4397940/+files/sleep_err_output.txt -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1301601 Title: [Dell Latitude E7440] suspend sometimes freezes when lock screen activates To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1301601/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
