[mythtv-users] Black screen after idle

[Stephen Worthington]

On Wed, 19 Aug 2020 19:08:05 -0700, you wrote:

>On Mon, Aug 17, 2020 at 2:37 AM Stephen Worthington <
>stephen_agent at jsw.gen.nz> wrote:
>
>> On Sun, 16 Aug 2020 21:06:22 -0700, you wrote:
>>
>> >
>> >On 8/16/20 4:25 PM, Jim Abernathy wrote:
>> >>
>> >>
>> >> On 8/16/20 6:57 PM, DryHeat122 wrote:
>> >>> I recently upgraded to Ubuntu 18.04/Myth 31.  I leave the frontend
>> >>> running all the time and just turn off the monitor when I'm not
>> >>> watching anything.  Twice now, the following has happened.  After the
>> >>> system has sat idle for some time (overnight this time) I turn on the
>> >>> monitor and the screen is black.  I cannot change to a terminal
>> >>> window with ctl-alt-F2.  However, I can SSH to the myth box from
>> >>> another machine and issue terminal commands just fine.  Rebooting
>> >>> fixes the problem.  I have all the screen-saver and sleep
>> >>> functionality turned off, and the monitor works fine on other inputs,
>> >>> so I don't think it's either of those things.
>> >>>
>> >>> I have searched the black screen symptom and the threads I find (for
>> >>> example this one
>> >>> <
>> https://askubuntu.com/questions/1085807/black-screen-after-installation-of-ubuntu-18-04
>> >)
>> >>> are about this problem happening at boot, not after the machine has
>> >>> been sitting idle for some time.  It also doesn't happen
>> >>> consistently, maybe twice in the last couple weeks.
>> >>>
>> >>> Has anyone experienced this problem before?  Any pointers for how to
>> >>> fix or troubleshoot? Thanks......Steve
>> >>
>> >> I've fought this problem off and on for many years and releases of
>> >> *buntu and mythtv.
>> >>
>> >> IMHO it's a linux problem. too many things control the power options.
>> >> On some systems I install the screensave and then disable it.  On
>> >> others I use the power settings. Generally I've found that I enable
>> >> the screensaver but set the time to never works the best.
>> >>
>> >> There are just too many things that seem to have access to control the
>> >> screen off and on.
>> >>
>> >> I have on occasions control-alt-F1 then logged in and restarted
>> >> lightdm to fix it without rebooting. sudo systemctl restart lightdm
>> >>
>> >> Jim A
>> >>
>> >> ***
>> >
>> >I have the same issue (Ubuntu 18.04/Myth30) but in my case hitting the
>> >Enter button on the remote restores normal operation so I haven't paid
>> >much attention.
>> >
>>
>> I have had this one once recently.  It went away when I hit the shift
>> key, which is what screen savers do.  I had to reboot to stop it
>> happening all the time, so it must be something that only happens on
>> occasional boots as I have not seen it before.
>>
>> Apart from the power and screen saver settings, the other thing that
>> needs to be set off is the DPMS option in /etc/X11/xorg.conf:
>>
>> Section "Monitor"
>>         Identifier "Sony TV"
>>         Option "DPMS"   "false"
>> EndSection
>>
>> Just had the problem reoccur so got to try these fixes.  Hitting shift did
>nothing.  Hitting enter played a recorded show, with audio but no video bc
>the screen is black.  esc stopped the playback.  ctl-alt-f1 does nothing.
>SSH from another machine and try @Stehpen's fix restarting lightdm and I
>get " Unit lightdm.service not found."  This reboot will install the edit
>to xorg.conf so we will see if that helps.

From that, I would say that you are not using lightdm as your display
manager.  Other display managers do not restart as well as lightdm, so
you might want to switch from whatever you are currently using (gdm?
gdm3?) to lightdm:

https://vitux.com/some-common-ubuntu-display-managers-and-how-to-switch-between-them/

I changed to using lightdm on my Ubuntu 18.04 box when I upgraded it
from 16.04 to 18.04 after I found that gdm had a bug that made my VNC
server (x11vnc) fail to work.

For XFCE4 (Xubuntu) on my MythTV boxes, I was able to re-enable
Ctrl-Alt-Backspace by adding this line:

XKBOPTIONS="terminate:ctrl_alt_bksp"

to my /etc/default/keyboard file.  Note that restarting X does not get
this option working - I had to do a full reboot.

I have also seen suggestions that even with Ctrl-Alt-Backspace
disabled, you can use AltGr-SysReq-K to do the same thing.  AltGr =
the right Alt key, SysReq = PrintScrn if your keyboard does not have
those markings.  That one did not work for me when I tried it on my
test Xubuntu 20.04.1 box, which has a clean new install of Xubuntu
20.04.1.