Hey there, I have been using Fedora Silverblue for a while now, I have most apps installed using Flatpak and some Overlayed packages (Mostly virtualization software and encryption software).
When I upgraded my base Tree (using rpm-ostree upgrade) and rebooted (using systemctl reboot) everything worked fine except being able to connect my second-monitor. I tried to troubleshoot but not sure what I should be looking for.
What happens when I connect an HDMI Cable
The screen starts flashing, in Gnome Settings I can see it detecting the 2nd display and losing it repeatedly)
Cannot find anything specific to the laptop, GPU or distro. A workaround would be boot into previous state of Fedora Silverblue, remove/rollback last update and use that older version until there is new kernel/driver update is release. Then try upgrading, expecting that issues that you having are resolved.
I had been doing that for like a month and a half, I needed to upgrade and didn’t know what was the package that was creating problems, when I connect the HDMI Cable there is a new entry in the Gnome Logs app (these messages are sent by gnome-shell):
Window manager warning: Overwriting existing binding of keysym 39 with keysym 39 (keycode 12).
I was troubleshooting the components and I did some tests:
TEST 1 - Laptop to another monitor
I tried, using the same Laptop and Cable connect to a television, it worked, this made me think that the problem was the Secondary Display. I then remembered that I had once (when I started having this problem) rolled back and the monitor worked, just not with the latest updates
Test 2 - Another device connecting to the Secondary Display
Since I cannot Rollback anymore (due to upgrading twice since the last time the monitor was connecting to my laptop), I tried to connect the monitor to a TV Box, it connected flawlessly
With these two test I conclude that there is no problem either on the cable or the secondary monitor, so I will do what @arturasb recomended and just wait for an update to a driver that works
Not necessarily true.
Above it was noted that a monitor was the issue, and since the hdmi standards are evolving it is possible that the hdmi port on the monitor has a different standard for connection than your laptop. The system upgrade may have simply exposed the incompatibility that was previously masked.
Testing the monitor on a different system does not mean it is good, but merely shows those two devices are compatible.
Testing a different monitor or a tv on your laptop would be a more definitive test since that verifies the port on the laptop as well. You seem to have done that with test 1 so this exposed the incompatibility between the devices as the cause.
In general, such device issues cannot be fixed unless one reports the bug
with specific details about the devices – both laptop and monitor
with specific details about the software versions that worked and did not work
When the developers have access to exactly the same circumstances (hardware and software) to identify the specific cause and design a fix.
It may be a software regression or it may be an actual hardware issue. This cannot be resolved (except maybe by chance) without the developers being aware of it.
, or wait for a fix, if the problem is caused by a bug, introduced by recent update.