Hi Daniel, Following the suggestion, MUTTER_DEBUG_FORCE_KMS_MODE=simple was in effect (gnome-shell logged "Added device '/dev/dri/card1' (i915) using non-atomic mode setting."), but it did not help.
I removed it again and collected a log with MUTTER_DEBUG=kms (default atomic mode). Attached: an excerpt with only modesets/hotplugs, and the full log. Two tests in the same session: - 13:20 locked with Super+L, 13:46 unlocked: external monitor came back. - 13:49:37 screen blanked by idle timeout (lock-delay 0), 13:52:20 woken up: external monitor stays at "no signal". In both cases mutter's KMS log looks the same: 1. A full modeset (ATOMIC_ALLOW_MODESET) for HDMI-1 (CRTC 308, connector 596, 3440x1440) succeeds. 2. About 2 s later the monitor briefly drops hotplug: meta_kms_connector_read_state: connector 596 appears to have been disconnected followed ~1 s later by meta_kms_connector_read_state: connector 596 connection has been restored before the timeout had expired on_udev_hotplug -> meta_kms_update_resources ... changes=0x0 3. No new modeset follows; page flips on CRTC 308 keep completing normally, yet the monitor shows no signal. So it looks like the HDMI link is lost during the monitor's short hotplug pulse while waking up, and mutter doesn't re-modeset because it treats the pulse as a non-event. A manual modeset (changing the refresh rate) restores the picture. On 24.04 this didn't happen; I wonder if the connection-change debounce is new since then. Correction to my report: "Unexpected non-NULL onscreen_native->next_frame" is logged when the outputs are disabled (right after "Committing disable-device transaction"), not at unlock, and it did not appear in the failing case. It's probably unrelated. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/2169932 Title: [i915] External HDMI monitor gets no signal after lock/unlock on 26.04 (regression from24.04) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/mutter/+bug/2169932/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
