"Noise" rendered in bottom-most row and right-most column

[WhyNotHugo]

Please fill out the following:

• Sway Version:

  • sway version 1.13-dev-a38d093cb (Prevent bogus repeated keypresses when reloading config #9106)
  • also with ec7e018
  • (need to double check, but I think I also saw this with 1.11)

• Configuration File:

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

• Description:

The bottom row of pixels in the screen renders some noise, which changes a few times per second. The same happens in the right-most column of pixels.

Here's a screenshot of a my screen rendering a full-screen terminal:

Here's photos of the bottom and right of my monitor:

This noise is not static, and moves around:

This doesn't happen when switching to another tty, or in any situation when sway is not running.

[WhyNotHugo]

The "noise" in those rows changes continuously once it starts. I've been seeing this for over two weeks now, but can't narrow down when it starts or how to reproduce.

[WhyNotHugo]

I ran swaymsg output DP-1 scale 1 and it went away, but when I ran swaymsg output DP-1 scale 1.6 again, it didn't re-appear.

[tekstryder]

Do you use fractional scaling?

Looks a lot like https://gitlab.freedesktop.org/wlroots/wlroots/-/work_items/3792

I can repro that at certain scaling factors.

[WhyNotHugo]

Using fractional scaling. My intuition tells me this might be the row of pixels left out of some rounding error.

My config has:

scale 1.66

swaymsg -t get_outputs says:

Scale factor: 1.658333

[tekstryder]

Yeah, prolly the wlroots issue I linked.

Can you repro without scaling? If yes, that's not the issue.

If no you can try wlroots MR https://gitlab.freedesktop.org/wlroots/wlroots/-/merge_requests/5071

Requires sway PR #8715

I think they were both rebased recently enough to apply cleanly to sway 1.12 rc2 and wlroots 0.20.0 tag, though I stopped building with them after finding the "right" scaling factors for my setup.

Could also be as simple as trying 1.661 or 1.662, etc. in your case.

[emersion]

Does this one help? https://gitlab.freedesktop.org/wlroots/wlroots/-/merge_requests/5171

[zDEFz]

This happens even without fractional scaling and for me the fix was to limit the render to WLR_RENDER_DRM_DEVICE=/dev/dri/renderD128

[WhyNotHugo]

Does this one help? https://gitlab.freedesktop.org/wlroots/wlroots/-/merge_requests/5171

Been using it for about a day without seeing the lines/noise again. Since I don't have any known trigger, I can't 100% confirm that the issue is gone, but will report back in future.

[WhyNotHugo]

Okay, it's been a few days and the issue hasn't resurfaces. Fairly confident that https://gitlab.freedesktop.org/wlroots/wlroots/-/merge_requests/5171 is a solid fix :)