bad resolution after monitor wakes up

NVIDIA Open GPU Kernel Modules Version

nvidia-open-dkms 580.95.05

Please confirm this issue does not happen with the proprietary driver (of the same version). This issue tracker is only for bugs specific to the open kernel driver.

• I confirm that this does not happen with the proprietary driver package.

Operating System and Version

Arch Linux

Kernel Release

6.17.1

Please confirm you are running a stable release kernel (e.g. not a -rc). We do not accept bug reports for unreleased kernels.

• I am running on a stable kernel release.

Hardware: GPU

GPU 0: NVIDIA GeForce RTX 5080

Describe the bug

when monitor powers off after idle and then wakes up, sometimes the resolution is at 640x480, sddm restart doesn't fix the problem, only reboot

I haven't noticed anything special in journal, just this one thing, but not sure it's connected:
Oct 13 18:03:03 mypc kwin_wayland[4462]: Atomic modeset test failed! Permission denied
Oct 13 18:03:03 mypc kwin_wayland[4462]: Applying output configuration failed!
Oct 13 18:03:03 mypc systemd[1]: Started dbus-:1.2-org.kde.powerdevil.backlighthelper@1.service.
Oct 13 18:03:03 mypc backlighthelper[4780]: no kernel backlight interface found
Oct 13 18:03:03 mypc org_kde_powerdevil[4603]: org.kde.powerdevil.chargethresholdhelper.getthreshold failed "Charge thresholds are not supported by the kernel for this hardware"
Oct 13 18:03:03 mypc org_kde_powerdevil[4603]: org.kde.powerdevil.backlighthelper.brightness failed

KDE (plasma 6.4.5)

happens with normal and dkms driver, newest and previous release

To Reproduce

configure energy setting for monitor power off after 5 mins idle, wait till monitor is off, then move mouse or press a key to wake up the monitor

it's random, so not every time is the resolution bad

sometimes when I wake up the monitor immediately it doesn't happen, is there some GPU "power off" when the monitor is off for some time ?

I have connected main monitor via DP and TV via HDMI (but disabled)

Bug Incidence

Sometimes

nvidia-bug-report.log.gz

nvidia-bug-report.log.gz

More Info

No response

Start with the attached nvidia-bug-report.log.gz and the reported kwin_wayland journal entries, then reproduce monitor power-off and wake with the DP-connected RTX 5080 under KDE Plasma. Compare successful and failed wake-ups, including the 640x480 fallback and atomic modeset error; done means the driver-specific cause is identified and resolution recovery is verified.