https://bugs.kde.org/show_bug.cgi?id=512881
Bug ID: 512881
Summary: External monitor does not stay in stand-by when system
is inactive
Classification: Plasma
Product: KScreen
Version First 6.3.6
Reported In:
Platform: Manjaro
OS: Linux
Status: REPORTED
Severity: normal
Priority: NOR
Component: common
Assignee: [email protected]
Reporter: [email protected]
Target Milestone: ---
SUMMARY
I am encountering a weird issue with an external monitor and I wonder if a KDE
bug may be triggering it or otherwise if KDE could start providing means to
mitigate it.
I have an aging (haswell) laptop that stays most of the time attached to a
modern external monitor (Philips 27 inches, 2560x1440 pixels). Because the
laptop is pre-usb C, the monitor is attached via its HDMI port. Plasma is
configured so that the laptop internal display is always kept off. It is also
configured to blank the screen after 5 minutes of inactivity. I am using the
wayland session.
Now, when the laptop is left inactive, the following happens:
- after 5 minutes the external monitor blanks
- after approximately 10 more seconds the external monitor reports “no
signal”
- after approximately 5 more seconds the external monitor goes in standby
so far so good, but then
- after about one more minute, the laptop plays a notification sound, the
internal display switches on, then it plays another notification sound the
internal display switches off and the the external monitor switches on. For a
few seconds a couple of notification popups stay visible saying that a display
has been detached and that a display has been attached.
At this point the monitor remains on with the lock screen. Interestingly, if at
this point I switch off the external monitor, the internal one will no more
blank either.
Any clue?
My understaning is that after some time the external display has entered stand
by, plasma thinks that it has been disconnected and acts consequently. But why?
Is this expected?
And then, why switching off the external monitor after the unplug-plug (false)
events does not let the internal laptop screen blank either? Is this expected
too?
Even if this is an issue with the monitor, is it possible to work it around? If
not, could it be possible to introduce configuration options mitigating this
issue?
Apparently this issue is well known: googling reveals that many people are/were
affected. However, for X11 there are workarounds. For wayland, no one seems to
know (possibly because every compositor does things in its own way).
STEPS TO REPRODUCE
1. Wait
OBSERVED RESULT
External monitor blanks, says "stand-by", switches on again
EXPECTED RESULT
External monitor stays blank
SOFTWARE/OS VERSIONS
Operating System: Manjaro Linux
KDE Plasma Version: 6.3.6
KDE Frameworks Version: 6.18.0
Qt Version: 6.9.2
Kernel Version: 6.16.8-1-MANJARO (64-bit)
Graphics Platform: Wayland
Processors: 8 × Intel® Core™ i7-4750HQ CPU @ 2.00GHz
Memory: 15.5 GiB of RAM
Graphics Processor: Intel® Iris® Pro Graphics P5200
Manufacturer: Notebook
Product Name: W740SU
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