PineTab2 screen won't turn back on until reboot

[KelsonV]

This is a different problem than the one that's been reported where the screen just won't turn on at all.

It's also different from suspend/hibernate not working, because the system is still running and reachable via SSH.

The screen is turning off after a period of inactivity (even though I've set power management not to turn off the screen) and won't turn back on until I reboot the tablet. The keys light up when I press them. The USB network adapter I have shows activity. I can even SSH in from another computer.

But the screen *does* come back on after reboot, whether I use the command line through an SSH session, or whether I just hold the power button down until it shuts off, then power it on again.

I'm currently using LxQt on the factory-shipped danctnix updated to the latest with pacman.

Has anyone else seen this? Any solution, or a tip for finding what else might be powering off the screen if my desktop session isn't doing it?

[cgbarros]

I haven't use LxQT for a while, but I assume it runs X and not Wayland, correct? If so, try to SSH into your device and run
$ xset -q

What do you get?

[KelsonV]

Thanks for pointing me in the right direction! Yeah, LXQT is running under X.  I had to script a loop to repeatedly save that output to a log, since the remote SSH session couldn't talk to the main X session, but what I found is:

1. DPMS is enabled, with the standby, suspend and off timeouts at 600 -- which it shouldn't be, because LXQt is set to not standby or suspend, but....
   
2. There is a bug in LXQT's power management where it doesn't always update DPMS's settings.
   
3. DPMS sees the monitor as off.
   

I also verified that the timeouts, lock screen etc. do still work correctly under Wayland on my device, so that's good to know!

That gives me a couple of approaches (workarounds, or manually installing the newer version, etc.) to prevent the problem of it turning off when I don't want it to. (I really do not miss all that messing with X configuration back in the old days, but hey, you gotta do what works.)

Then I need to figure out how to get it to turn back on. If LxQt's own power management works right (except for the dpms issue), then problem solved. It not, I figure I'll experiment with blank, standby, and suspend to see which ones (if any) the display recovers from.



--------------------
For the record: Full output of xset -q after the display turns off:

Code:

Keyboard Control:
  auto repeat:  on    key click percent:  0    LED mask:  00000000
  XKB indicators:
    00: Caps Lock:  off    01: Num Lock:    off    02: Scroll Lock: off
    03: Compose:    off    04: Kana:        off    05: Sleep:      off
    06: Suspend:    off    07: Mute:        off    08: Misc:        off
    09: Mail:        off    10: Charging:    off    11: Shift Lock:  off
    12: Group 2:    off    13: Mouse Keys:  off
  auto repeat delay:  500    repeat rate:  33
  auto repeating keys:  00ffffffdffffbbf
                        fadfffefffedffff
                        9fffffffffffffff
                        fff7ffffffffffff
  bell percent:  0    bell pitch:  400    bell duration:  100
Pointer Control:
  acceleration:  2/1    threshold:  4
Screen Saver:
  prefer blanking:  yes    allow exposures:  yes
  timeout:  600    cycle:  600
Colors:
  default colormap:  0x20    BlackPixel:  0x0    WhitePixel:  0xffffff
Font Path:
  built-ins
DPMS (Display Power Management Signaling):
  Standby: 600    Suspend: 600    Off: 600
  DPMS is Enabled
  Monitor is Off

[diederik]

The screen is turning off after a period of inactivity (even though I've set power management not to turn off the screen) and won't turn back on until I reboot the tablet. The keys light up when I press them. The USB network adapter I have shows activity. I can even SSH in from another computer.

But the screen *does* come back on after reboot, whether I use the command line through an SSH session, or whether I just hold the power button down until it shuts off, then power it on again.

I'm currently using LxQt on the factory-shipped danctnix updated to the latest with pacman.

Has anyone else seen this? Any solution, or a tip for finding what else might be powering off the screen if my desktop session isn't doing it?

I'm using a self-assembled Debian (Trixie) system with self-compiled kernel running KDE, and I've run into this problem too.
AFAICT it's all running Wayland, perhaps except SDDM.

I haven't found a solution yet, but I'm very much interested in one.
Haven't verified if it's also present in the Danctnix system though.