For months, I have been using 16.04 with a Dell U2415 monitor and an AMD desktop. I was able to suspend and then resume. In the past few days, the monitor is dark when I resume and I have to power down and re-start. Might this be caused by any recent OS updates? (I have installed them all)

UPDATE: The problem I describe happens with 4.4.0-148-generic, but not with 4.4.0-146-generic.

June 4, 2019: I installed the update for 4.4.0-150-generic, but that does not solve the problem. Fortunately, I modified apt-auto-removal to save 3 old kernels, so I can still boot 4.4.0-146-generic.

June 20, 2019: I installed the update for 4.4.0-151-generic, but that also does not solve the problem.

June 30, 2019: I installed the update for 4.4.0-154-generic, but that also does not solve the problem.

July 31, 2019: I installed the update for 4.4.0-157-generic, but that also does not solve the problem. (Reminder: 4.4.0-146-generic does not have the suspend problem)

Aug. 14, 2019: I installed the update for 4.4.0-159-generic, but that also does not solve the problem.

Sept. 5, 2019: I installed the update for 4.4.0-161-generic, but that also does not solve the problem. (Reminder: 4.4.0-146-generic does not have the suspend problem)

Sept. 18, 2019: I installed the update for 4.4.0-164-generic, but that also does not solve the problem. 4.4.0-146-generic does not have the suspend problem. Does anyone have any idea: (a) Why all versions I have tried beyond 146 have the problem? (b) Why the problem has persisted over several versions? (c) What causes the problem?

Oct. 8, 2019: I installed the update for 4.4.0-165-generic, but that also does not solve the problem. 4.4.0-146-generic does not have the suspend problem. Again, does anyone have any idea: (a) Why all versions I have tried beyond 146 have the problem? (b) Why the problem has persisted over several versions? (c) What causes the problem?

Oct. 22, 2019: I installed the update for 4.4.0-166-generic, but that also has the suspend problem. 4.4.0-146-generic does not have the suspend problem. Every version that I have tried after that one has the problem. I hope someone can tell me what is going on.

Nov. 14, 2019: I installed the update for 4.4.0-169-generic, but that also has the suspend problem. 4.4.0-146-generic does not have the suspend problem. Every version that I have tried after that one has the problem. Surely someone knows what is going on.

Jan. 09, 2020: I installed the update for 4.4.0-171-generic, but that also has the suspend problem. 4.4.0-146-generic does not have the suspend problem. Every version that I have tried after that one has the problem. Surely someone knows what is going on. Also, I plan to upgrade to 20.04 when it is ready. Can I expect that version to have this suspend problem, too?

Jan. 28, 2020: I installed the update for 4.4.0-173-generic, but that also has the suspend problem. 4.4.0-146-generic does not have the suspend problem. Every version that I have tried after that one has the problem. Can I somehow use 4.4.0-173-generic with display drivers and/or other display software from 146? Can I expect Ubuntu 20.04 to have this suspend problem, too?

Feb. 20, 2020: I installed the update for 4.4.0-174-generic, but that also has the suspend problem. Every version that I have tried after 4.4.0-146-generic has the problem. My video hardware is part of my MSI mainboard. (System Settings says video is AMD RS780.) Suppose I plug a video board into a PCI or PCIe slot. Might that solve this problem?

April 10, 2020: I installed the update for 4.4.0-177-generic, That has the suspend problem. Every version that I have tried after 4.4.0-146-generic has the problem. My video hardware is part of my MSI mainboard. (System Settings says video is AMD RS780.) Suppose I plug a video board into a PCI or PCIe slot and use that instead of the mainboard's video. Might that solve this problem? Can I expect Ubuntu 20.04 to have this suspend problem, too?

May 3, 2020: I installed the update for 4.4.0-178-generic, That has the suspend problem. Every version that I have tried after 4.4.0-146-generic has the problem. Might I be able to wake up the monitor by pressing some keyboard combination instead of having to restart? Might I be able to use video drivers or other software from ver. 146 in ver. 178? Can I expect Ubuntu 20.04 to have this suspend problem, too?

May 7, 2020: I just installed a new update to driver firmware. I was hoping that that would solve the suspend problem, but, alas, it does not.

May 19, 2020: I installed the update for 4.4.0-179-generic, That has the suspend problem, too. Every version that I have tried after 4.4.0-146-generic has the problem. Might I be able to use video drivers or other software from ver. 146 in ver. 179? Can I expect Ubuntu 20.04 to have this suspend problem, too?

June 11, 2020: I installed the update for 4.4.0-184-generic, That has the suspend problem, too. Every version that I have tried after 4.4.0-146-generic has the problem. Might I be able to use video drivers or other software from ver. 146 in ver. 184? Can I expect Ubuntu 20.04 to have this suspend problem, too?

July 10, 2020: I installed the update for 4.4.0-185-generic, That has the suspend problem, too. Every version that I have tried after 4.4.0-146-generic has the problem. Can I expect Ubuntu 20.04 to have this suspend problem, too?

July 27, 2020: I have installed the update for 4.4.0-186-generic in Ubuntu 16.04 LTS. That (as I expected) has the suspend problem, too. Every version that I have tried after 4.4.0-146-generic has the problem. I have read that Ubuntu 18.04 does not even have the suspend button (but it can be made to appear). Has Ubuntu given up on the idea of saving energy by suspending CPU operation? Can I expect Ubuntu 20.04 to have this suspend problem, too? If so, do other Linux distros properly support "suspend"?

Aug. 20, 2020: I installed the update for 4.4.0-187-generic in Ubuntu 16.04 LTS. That new version (as I expected) has the suspend problem, too. Every version that I have tried after 4.4.0-146-generic has the problem. Has Ubuntu given up on the idea of saving energy by suspending CPU operation?

Aug. 25, 2020: Good news. Yesterday, I installed 18.04.5 LTS. My suspend problem is now gone!