dpms off: HDMI monitor wakes up immediately due to hotplug disconnect/reconnect loop

[samsyu518]

After running hyprctl dispatch dpms off, my HDMI monitor (MSI MP273U) wakes up within seconds. The monitor does not stay off.

Hardware

• GPU: AMD Radeon HD 7750 (Cape Verde PRO)
• HDMI-A-1: MSI MP273U (2024) — affected
• DP-1: BenQ GL2450H — not affected

Root Cause

The MSI monitor reports a DRM connector disconnect when it receives no signal, then immediately reconnects.
This triggers repeated hotplug events, causing Hyprland to call onNewMonitor and re-enable the monitor, overriding the DPMS off state.

niri msg action power-off-monitors # works correctly on the same hardware

I found that niri handles this case in src/backend/tty.rs:

// Some buggy monitors replug upon powering off, so powering on here would
// prevent such monitors from powering off. Therefore, we avoid
// unconditionally powering on.
if !niri.monitors_active {
    compositor.clear();
}

This behavior started after the aquamarine migration (commit 016da23, 2024-07-21) The wlroots-based backend did not trigger this issue

Related

• Discussion A monitor which is DPMS'd off is quickly removed then added again on wake #13654
• Discussion dpms off causes the monitor to be unplugged after some minutes #11356

log

Log evidence (repeats continuously after dpms off):

udev: new udev change event for card0
drm: Got a hotplug event for /dev/dri/card0
drm: Connector HDMI-A-1 is not connected, removing old crtc 59
drm: Connector HDMI-A-1 connected
drm: Connecting connector HDMI-A-1, CRTC ID 59

[falkkyburz]

When seeing this log, I am wondering if you are also affected by this issue: #14485
It is caused by the fast HDMI connection flapping when changing the monitor input source.

Edit: This might be a duplicate of you issue: #12791

[samsyu518]

The fix in PR #14818 (now merged) addresses this specifically by re-applying dpms off when a monitor reconnects via hotplug while DPMS is already off.

I think The behavior in #14485 and #12791 does seem related, all cases involve monitors that disconnect and reconnect on HDMI during no-signal or input switch.

I tested by building Hyprland from source and running it in my archlinux. It works

Switched to a TTY, then ran:

git clone https://github.com/hyprwm/Hyprland
cd Hyprland
git submodule update --init
cmake -B build -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX=/usr
cmake --build build -j$(nproc)

dbus-run-session ~/Hyprland/build/Hyprland

hyprctl dispatch dpms off