Re-enabling output sometimes fail

[jbeich]

Regressed by #2118. See debug log.

Steps to reproduce

1. Start Sway
2. Disable display
3. Enable display
4. Repeat (2) and (3) until black screen

Actual result

Display wakes up but with no signal goes back to sleep. On console:

[main.c:168] Destroying output DP-1 (...)
[ERROR] [backend/drm/renderer.c:379] Tried to acquire an FB with a NULL BO
[ERROR] [backend/drm/renderer.c:379] Tried to acquire an FB with a NULL BO
[ERROR] [backend/drm/drm.c:754] Failed to initialize renderer on connector 'DP-1': initial page-flip failed
[ERROR] [backend/drm/drm.c:835] Failed to initialize renderer for plane
[sway/config/output.c:423] Failed to commit output DP-1
[ERROR] [backend/drm/renderer.c:379] Tried to acquire an FB with a NULL BO

Expected result

Display works like before sleep

Environment

$ cc --version
FreeBSD clang version 10.0.0 (git@github.com:llvm/llvm-project.git llvmorg-10.0.0-0-gd32170dbd5b)
Target: x86_64-unknown-freebsd13.0
Thread model: posix
InstalledDir: /usr/bin

$ sway --version
sway version 1.2-rc1-334-g5e5e5f2e
wlroots version 0.10.0-107-g61d6408f

$ cat /tmp/sway.conf
bindsym Ctrl+Alt+BackSpace exit
bindsym Down output * dpms off
bindsym Up output * dpms on

output * background #15c6ac solid_color

[emersion]

Can you try #2168?

[jbeich]

Can you try #2168?

After applying I can't reproduce anymore. Thanks!