External Screen issues with dual GPU system

[sriedel]

• Sway Version: sway version 1.2 (Aug 29 2019, Arch Linux)
• Debug Log: https://gist.github.com/sriedel/bf64d0675fda57820b3df3d1c90e92a3
• Configuration File: Issue occurs with default configuration

I have two issues with external screens which are probably closely related, thus only one bug report.

My setup is a laptop with an external screen (Dell UltraSharp U2718Q identified as DP-1; the internal screen is identified as eDP-1), connected via display port. There are two GPUs: the cpu-internal i915 as well as a discrete Quadro M1000M running the nouveau driver. The external screen connections are only attached to the Quadro GPU.

When the external screen is disconnected sway becomes unresponsive to mouse and keyboard input, requiring a reboot since I can't kill sway via the mod+shift+e key combo. If I reinsert the display port plug while in this state, the external screen shows the appropriate workplaces again, however sway remains unresponsive to keyboard and mouse inputs. (this is should in the debug log - disconnecting the external screen, waiting a bit then reconnecting the screen, waiting a few seconds and then rebooting)

If I put the laptop to sleep via systemctl suspend before disconnecting the external screen, and reconnect before waking the laptop back up, everthing is as it should be.

If I put the laptop to sleep before disconnecting and wake the laptop without the external screen attached, the workplaces migrate to the internal screen and everything continues to work as expected. When I re-attach the external screen in this state, regardless of the laptops sleep state, the external screen shows the workspaces that were originally there (even if swaylock is running and the internal screen is locked and blanked by swaylock). The workspaces that were on the external screen before the screen was disconnected reappear on the external screen. I can move my mouse to the external screen as expected, however sway on the external screen (and only on the external screen) is unresponsive to mouse clicks and keyboard input.

Disabling the external screen in this state with "swaymsg output DP-1 disable" disables the screen as expected. Re-enabling the screen via "swaymsg output DP-1 enable" leaves the screen blank, the workspaces jump back to the external screen though and I can move the mouse cursor to the external screen (the mouse cursor is the only thing visible there). In this state I need to restart sway in order to interact with the external screen again as expected.

No coredumps are generated as far was I can see.