** Description changed: [ Impact ] On some machines when the screen blanks, the LCD backlight stays on. + + This was traced to two issues in mutter: + https://gitlab.freedesktop.org/drm/amd/-/issues/662#note_2731990 + + > I recently discovered that mutter was disabling DPMS off again on receiving a hotplug event from udev. I don't know any reason for that, removing it allows my monitor to go to sleep eventually. Note that when mutter runs on Xorg, it doesn't explicitly disable DPMS off but just queries the current DPMS state from Xorg. Since the issues are reproducible with Xorg and other Wayland DEs, maybe Xorg drivers and other Wayland compositors do something like what mutter did as well. + > On receiving a hotplug event from udev, mutter now waits until no further hotplug events have arrived for at least one second, only then does it query the current KMS state. This avoids issues due to monitors generating hotplug events and temporarily appearing disconnected. It might be nice if something like this was done in the kernel if possible, not sending any hotplug event to user space if EDID hasn't changed, or something along those lines. [ Workarounds (reported to work by some people) ] * Configure the monitor (in its own menus) to not auto-switch inputs. * Change from HDMI to DisplayPort cables. * Disable HDMI audio output. [ Test Plan ] 0. Make sure you're using an LCD (not OLED) so you can see if the backlight is on. - 1. In Settings -> Power -> Screen Blank, set the inactivity period to 1 minute. - 2. Verify after 1 minute that the screen is blank and the backlight is also visibly off. + 1. Log-in to an Ubuntu Wayland desktop session + 2. In Settings -> Power -> Screen Blank, set the inactivity period to 1 minute. + 3. Verify after 1 minute that the screen is blank and the backlight is also visibly off. + 4. Verify that the screen is turned back on after interacting with the system. + + [ Regression Test Plan ] + + 1. Plug in a monitor: + -> Verify that the desktop extends to the new monitor + 2. Unplug a monitor: + -> Verify that mutter does not crash and log you out [ Where problems could occur ] - [ Other Info ] + Mutter is the GNOME component driving the display. + The patches modify how mutter reacts to monitor hotplug events and when it should turn the monitor back ON. + Problems would manifest when plugging in/out monitors. + The "Regression Test Plan" tries to verify that no regressions are introduced.
-- You received this bug notification because you are a member of Desktop Packages, which is subscribed to mutter in Ubuntu. https://bugs.launchpad.net/bugs/1971434 Title: Display powersave only blanks, but does not turn off Status in GNOME Settings Daemon: New Status in Mutter: New Status in mutter package in Ubuntu: Fix Released Status in mutter source package in Jammy: Triaged Status in mutter source package in Noble: Triaged Status in mutter source package in Oracular: Won't Fix Status in mutter source package in Plucky: Fix Released Status in mutter source package in Questing: Fix Released Bug description: [ Impact ] On some machines when the screen blanks, the LCD backlight stays on. This was traced to two issues in mutter: https://gitlab.freedesktop.org/drm/amd/-/issues/662#note_2731990 > I recently discovered that mutter was disabling DPMS off again on receiving a hotplug event from udev. I don't know any reason for that, removing it allows my monitor to go to sleep eventually. Note that when mutter runs on Xorg, it doesn't explicitly disable DPMS off but just queries the current DPMS state from Xorg. Since the issues are reproducible with Xorg and other Wayland DEs, maybe Xorg drivers and other Wayland compositors do something like what mutter did as well. > On receiving a hotplug event from udev, mutter now waits until no further hotplug events have arrived for at least one second, only then does it query the current KMS state. This avoids issues due to monitors generating hotplug events and temporarily appearing disconnected. It might be nice if something like this was done in the kernel if possible, not sending any hotplug event to user space if EDID hasn't changed, or something along those lines. [ Workarounds (reported to work by some people) ] * Configure the monitor (in its own menus) to not auto-switch inputs. * Change from HDMI to DisplayPort cables. * Disable HDMI audio output. [ Test Plan ] 0. Make sure you're using an LCD (not OLED) so you can see if the backlight is on. 1. Log-in to an Ubuntu Wayland desktop session 2. In Settings -> Power -> Screen Blank, set the inactivity period to 1 minute. 3. Verify after 1 minute that the screen is blank and the backlight is also visibly off. 4. Verify that the screen is turned back on after interacting with the system. [ Regression Test Plan ] 1. Plug in a monitor: -> Verify that the desktop extends to the new monitor 2. Unplug a monitor: -> Verify that mutter does not crash and log you out [ Where problems could occur ] Mutter is the GNOME component driving the display. The patches modify how mutter reacts to monitor hotplug events and when it should turn the monitor back ON. Problems would manifest when plugging in/out monitors. The "Regression Test Plan" tries to verify that no regressions are introduced. To manage notifications about this bug go to: https://bugs.launchpad.net/gnome-settings-daemon/+bug/1971434/+subscriptions -- Mailing list: https://launchpad.net/~desktop-packages Post to : [email protected] Unsubscribe : https://launchpad.net/~desktop-packages More help : https://help.launchpad.net/ListHelp
