SUMMARY KDE switches to the lowest possible resolution when a secondary display is attached but not yet turned on. It never restores the correct resolution when the displayed is powered up, detached and reattached. I use a USB-C port replicator with my XPS 9360 laptop and a fullHD display attached via an HDMI cable to the replicator. STEPS TO REPRODUCE 1. Attach the USB-c port replicator to the machine with the HDMI cable already attached but the display itself powered down 2. A new display appears in the Settings > Displays with 480p resolution (DP-1) but of course cannot be used. 3. Power-up the external display 4. KDE will switch the display to 480p resolution and the displays becomes usable 5. Detach the port replicator and re-attach it. A proper display name will now appear in Displays. OBSERVED RESULT KDE still keeps the 480p resolution instead of switching to the correct, last known resolution of the display EXPECTED RESULT KDE restores the correct, last-known resolution of the display. SOFTWARE/OS VERSIONS Linux/KDE Plasma: Ubuntu 20.04 (available in About System) KDE Plasma Version: 5.18.5 KDE Frameworks Version: 5.68.0 Qt Version: 5.12.8 ADDITIONAL INFORMATION It is like KDE somehow identifies a virtual display on the port replicator and handles that instead of the actual display at the other end of the port replicator. When the HDMI cable is directly attached, the behaviour is different.
Thank you for the bug report. Unfortunately we were not able to get to it yet. Can we ask you to please check if this is still an issue with Plasma 5.25 or 5.26? If it is, please change the status to CONFIRMED when replying. If not, or if you can't because you no longer use this setup, you can change the status to RESOLVED WORKSFORME. Thanks a lot!
Dear Bug Submitter, This bug has been in NEEDSINFO status with no change for at least 15 days. Please provide the requested information as soon as possible and set the bug status as REPORTED. Due to regular bug tracker maintenance, if the bug is still in NEEDSINFO status with no change in 30 days the bug will be closed as RESOLVED > WORKSFORME due to lack of needed information. For more information about our bug triaging procedures please read the wiki located here: https://community.kde.org/Guidelines_and_HOWTOs/Bug_triaging If you have already provided the requested information, please mark the bug as REPORTED so that the KDE team knows that the bug is ready to be confirmed. Thank you for helping us make KDE software even better for everyone!
This bug has been in NEEDSINFO status with no change for at least 30 days. The bug is now closed as RESOLVED > WORKSFORME due to lack of needed information. For more information about our bug triaging procedures please read the wiki located here: https://community.kde.org/Guidelines_and_HOWTOs/Bug_triaging Thank you for helping us make KDE software even better for everyone!