Bug 457413

Summary: First character typed while the screen is in power saving mode is lost
Product: [Plasma] plasmashell Reporter: Patrick Silva <bugseforuns>
Component: Power management & brightnessAssignee: Plasma Bugs List <plasma-bugs-null>
Status: CONFIRMED ---    
Severity: minor CC: bshah, natalie_clarius, nate, xaver.hugl
Priority: NOR    
Version First Reported In: 6.2.4   
Target Milestone: 1.0   
Platform: Arch Linux   
OS: Linux   
Latest Commit: Version Fixed/Implemented In:
Sentry Crash Report:

Description Patrick Silva 2022-08-02 14:07:21 UTC 
SUMMARY
previously reported as bug 397318


STEPS TO REPRODUCE
1. set the time out to switch the screen off to 1 minute in power management settings
2. lock the screen
3. wait until the screen switches off
4. type your password and press enter


OBSERVED RESULT
unlocking fails due to wrong password

EXPECTED RESULT
the screen should be unlocked

SOFTWARE/OS VERSIONS
Operating System: KDE neon Unstable Edition
KDE Plasma Version: 5.25.80
KDE Frameworks Version: 5.97.0
Qt Version: 5.15.5
Graphics Platform: Wayland
Comment 1 Nate Graham 2022-08-02 14:58:58 UTC 
Is the whole system asleep, or just the screen? You could check by keeping some music playing in the background while the screen locks and then turns off.
Comment 2 Patrick Silva 2022-08-02 15:03:23 UTC 
Just the screen. I always disable automatic suspend to RAM on my systems.
Comment 3 Nate Graham 2022-08-02 16:13:53 UTC 
Can reproduce. Seems like a powerdevil issue; it eats the keystroke, so it doesn't make it to the screen locker (or anything else; maybe the screen wasn't locked).
Comment 4 Zamundaaa 2022-08-07 00:21:21 UTC 
is this on Wayland, or on X? On Wayland, this is intentional and built into KWin
Comment 5 Patrick Silva 2022-08-07 00:23:34 UTC 
(In reply to Zamundaaa from comment #4)
> is this on Wayland, or on X? On Wayland, this is intentional and built into
> KWin

Wayland.
Comment 6 Nate Graham 2022-08-07 00:43:15 UTC 
Do you happen to know the reasoning behind it being an intentional behavior?
Comment 7 Zamundaaa 2022-08-07 15:54:23 UTC 
It was introduced with https://invent.kde.org/plasma/kwin/-/commit/57b11f84296b69944b907a89d403dc50d36a75dc, but the commit message doesn't really mention anything specific.
I think it's to allow you to press any key without consequences in order to wake up the PC though, instead of having to care about what you press. It's also consistent with standby, where the input event for waking up is not passed on to the system either (which KWin has no control over, either the kernel or firmware does this)
Comment 8 Nate Graham 2022-08-08 15:44:56 UTC 
That makes sense when the screen's not locked, because otherwise by waking up your screen you'd have random characters typed somewhere on the screen. But when the screen is locked, I think it makes sense to allow input through so that you can wake up the screen and also unlock with the same thing. It would be the same principle by which we allow input through on the lock screen even when the interactive UI isn't visible yet.