Before I could plug the HDMI cable and the secondary monitor showed up and the option to choose what to with the screen was made active. When I unplugged the cable, the option was grayed out and the monitor defaulted to its usual one monitor setup. After 5.17 update that is no longer true. When plugging in the secondary monitor nothing happens. I must at least reload session but this produces incredibly buggy effects so the real solution now is to REBOOT the system to get the second monitor working. The same issue is when I detach or turn off the secondary monitor. The system still "thinks" the other monitor is on and providing output for it. The multi-monitor options are active. Again, the reboot is the only real workable solution now. To sum up, a reboot is needed for proper detection of the additional monitor was plugged in or off. Something is failing hard here. Again, reloading session somewhat helps but produces incredibly buggy results so the issue somewhat persists between sessions. Together with other multi-monitor issues, Plasma 5.17 crippled the experience seriously.
Just fixed!
Awesome! Thanks :). I'll wait for the update then and report if it helped.
(In reply to Nate Graham from comment #1) > Just fixed! How should https://cgit.kde.org/kscreen.git/commit/?h=Plasma/5.17&id=2ab4c2f136c5d7c00cd08e99f43670b55a2a6a58 fix the issue described here? I could use some more information from you: run xrandr -q before and after the hot plug. What does the screen configuration KCM KScreen show?
Laptop's screen: Screen 0: minimum 320 x 200, current 3520 x 1080, maximum 16384 x 16384 eDP-1 connected primary 1920x1080+1600+0 (normal left inverted right x axis y axis) 382mm x 215mm Secondary monitor: HDMI-1-3 connected 1600x900+0+0 (normal left inverted right x axis y axis) 434mm x 236mm After I unplugged it, the system didn't detect it, but when I ran command xrandr -q it blinked and recognized the other monitor is off. So somehow using xrandr updates the state but without it, it's not. The other way is true as well. I plugged in the second monitor, monitor detected that something was plugged and showed "scanning HDMI signal" but there was no signal because the system didn't react to it. This wasn't changing untill I used xrandr command again, screens flickered, the picture in secondary monitor showed up. By the way, browser and terminal window moved to the second screen although they were originally in the first one. One could write a book about multi-monitor setup inconsitencies and weird things.
I updated to Plasma 5.17.1, rebooted, unplugged the secondary monitor and no change. The system still isn't aware of that fact and is outputting to the unexisting monitor. It looks like the concerns and doubts of some users here came true. The fix wasn't addressing this issue at all.
Today I plugged in the second monitor and it was detected automatically, so it looks like I need to gather more data to judge what is going on and if the patch really helped or not.
Darn. In my recent experience, it detects monitors that are plugged in, but has trouble with monitors that are unplugged.
Yes, that is my experience too. So it got better with 5.17.1 update but partially. This is not done yet.
I went to debug this with Roman today but found that I'm no longer able to reproduce the issue with either Plasma 5.17.3 or git master. Are you?
Out of curiosity, can you reproduce this only when you unplug the device while it's off/asleep, or can you also reproduce it when you unplug the device while it's displaying something?
*** This bug has been marked as a duplicate of bug 372837 ***
Some friends said the problem disappeared after upgrading to kernel 5.3.8. I also didn't reproduce this problem for the whole week, plugging and unplugging HDMI many times. If any of you can still reproduce this, what is the kernel version you are using? Can you try to upgrade to kernel 5.3.8 and retry?
I have kernel 5.3.10 and just upgraded to Plasma 5.17.3. Unplugging secondary monitor don't trigger any reaction. So the issue is still there :(