Changed display settings not being applied reliably
Affected version
- Arch Linux 5.10.10-arch1-1
- Gnome Shell 3.38.3
- GNOME Wayland
- Dell XPS 15 2-in-1 (Intel iGPU, AMD dGPU; uses PRIME)
- Two 4k displays connected using DisplayPort (one over a thunderbolt dock, the other directly)
Bug summary
When configuring external displays the display layout and UI-scaling are not applied reliably. After the changes have been made, and the Apply button has been pressed, the changes are initially applied successfully, but are then reset within a few seconds, all while the "Confirm Changes" / "Revert Changes" dialog is still open. Sometimes the "Confirm Changes" button works to apply the changes, other times it is the "Revert Changes" button that leads to the intended result, with the "Confirm Changes" button actually leading to the same configuration as was present prior to the changes. Sometimes neither button works and the changes are never applied (this seems to be the case when the changes affect internal display as well)
Changes to only the internal display do not have this issue.
Steps to reproduce
- Open gnome-settings (and one other program window for each display to make seeing the changes easier)
- Rearrange displays and set UI-scaling to 200% for each internal display
- Click the "Apply" button
- Wait a while until the images displayed stabilize (i.e. no more flashing, re-scaling, re-ordering, etc.)
- Press one of the buttons in the "Confirm Changes" dialog
What happened
Sometimes the changes are applied successfully, one short period of flashing, re-scaling, re-ordering, after that a stable image. "Confirm Changes" works as intended and so does "Revert Changes".
Other times the changes are applied after clicking the "Apply" button, but are then reset in another bout of flashing, re-scaling, etc., all this before interacting with the "Confirm Changes" dialog. If this occurs it seems clicking "Revert Changes" is actually what leads to the intended result. Doing so causes another bout of flashing, etc., but leads to the new configuration. Clicking "Confirm Changes" seems to keep the settings that were reset before interacting with the dialog.
If the internal display is affected by the changes (e.g. it's scaling and/or position) the changes might flash after applying and then reset only for then neither button in the dialog to lead to the desired configuration. Both buttons would reset to the configuration before the changes.
What did you expect to happen
The changes are applied as they were configured in gnome-settings.
Relevant logs, screenshots, screencasts etc.
I don't know which logs might be helpful for resolving this issue, but will try to provide them if possible, if you tell me where to look.
I currently don't have the time, but I will try to provide some screencasts / filmed videos of the monitors in the coming days.
Additional notes
gnome-shell#3435 (closed) might be related. #1629 might also be related to some degree.