No signal on external display, sometimes it works for less than a second

[WhyNotHugo]

Please fill out the following:

• Sway Version:
  • sway version 1.10
  • sway version 1.10-dev-801bc76c

(reproducible with both versions)

• Debug Log:

  • https://paste.sr.ht/blob/df166e1bba9a29e80f490d8259b4f7307a9cd67d
  • See my comment below for a log which includes stderr and uses a minimal config.

• Configuration File:

  • https://git.sr.ht/~whynothugo/dotfiles/tree/main/item/home/.config/sway/config

• Stack Trace:

  • No crash

• Description:

When I plug in this particular external display, no output signal is sent. Sometimes sway won't even show the output as connected. Other times, it starts blinking the laptop display AND the external display continuously over and over until I unplug the external display.

The logs indicate 00:00:00.510 [DEBUG] [wlr] [backend/drm/fb.c:147] Failed to get DMA-BUF from buffer. I don't know what this means.

[emersion]

Anything in dmesg?

The logs indicate 00:00:00.510 [DEBUG] [wlr] [backend/drm/fb.c:147] Failed to get DMA-BUF from buffer. I don't know what this means.

This can happen when a window is made fullscreen and is harmless (just means direct scanout is not used).

[WhyNotHugo]

There's no fullscreen window in this context. The line following this also indicates a failure, I don't know if they're related:

00:00:00.521 [DEBUG] [wlr] [backend/drm/fb.c:147] Failed to get DMA-BUF from buffer
00:00:00.521 [DEBUG] [wlr] [backend/drm/drm.c:773] connector eDP-1: Failed to import buffer for scan-out

Will produce dmesg shortly.

[alimg]

I was having the same symptoms as yours, display was going dark every every few seconds, sometimes never coming back if I launch few apps. At first I though it was a sway issue, but then I tried some other wayland compositors i tried also had it, both wlroots and non-wlroots based.

After some googling, I found a solution at Arch wiki 1 which seem to help. According to this reddit post 2 problem is related having high refresh rate monitors.

[WhyNotHugo]

I'm using an Intel GPU, not AMD, so I don't think it's the same issue. This display worked a year ago too (it regressed only some a couple of months ago).

[WhyNotHugo]

Here's the dmesg output, stating a second before I connect the output:

[  217.286991] usb 3-6: new full-speed USB device number 6 using xhci_hcd
[  217.425123] usb 3-6: not running at top speed; connect to a high speed hub
[  217.429153] usb 3-6: New USB device found, idVendor=2109, idProduct=0103, bcdDevice= 5.c7
[  217.429159] usb 3-6: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[  217.429160] usb 3-6: Product: USB 2.0 BILLBOARD
[  217.429161] usb 3-6: Manufacturer: VLI Inc.
[  217.429161] usb 3-6: SerialNumber: 0000000000000001
[  272.651699] usb 3-6: USB disconnect, device number 6
[  319.206985] warning: `Socket Thread' uses wireless extensions which will stop working for Wi-Fi 7 hardware; use nl80211

I produced new logs with a shorter configuration file:

exec foot

Is is here: https://paste.sr.ht/~whynothugo/18e0bc34ec4df49f94257dab634ff96b68bc3670

I think I produced the original logs with stdout and not stderr, so these might contain additional information (and a lot less noise).

When I plugged in the external display, it indicated that it had no signal. Meanwhile, the laptop internal display started blinking on and off for about half a second on and half a second off. It did this about maybe 6-10 times. Finally, the laptop screen remained on and the external display remained off.

I discovered that if I switch to another VT and back, both outputs work just fine. I did this near the end of the test, and the logs for the seat change start around line 1891:

https://paste.sr.ht/~whynothugo/18e0bc34ec4df49f94257dab634ff96b68bc3670#sway.out-L1891

The display also works fine for the Linux console.