[BUG] Bigscreen Beyond: Headset screen tearing and right-eye distortion when using SteamVR overlay on Linux

[trashhead101]

(edit: A fix for both is explained in my comment.)

I am using a Bigscreen Beyond 2e on Arch Linux and I am encountering two separate rendering issues that only affect the headset view (not the mirrored desktop view).

Issue 1: Severe headset-only screen tearing

In all VR applications, including SteamVR Home, there is severe screen tearing visible only inside the headset. The mirrored view on the monitor appears normal.

For games, this can be mitigated by enabling the setting
“Use legacy mode for motion smoothing”
(name translated 1:1 from German: „Klassischen Modus für Bewegungsglättung verwenden“; wording may differ in English).

However, this workaround does not affect SteamVR Home. SteamVR Home continues to exhibit heavy tearing regardless of this setting.

Issue 2: Right-eye distortion when SteamVR overlay is opened in-game

When running a game and opening the SteamVR overlay, the image in the right eye becomes heavily warped, comparable to a fisheye distortion, aswell as lifted a bit to the top. The left eye remains correct, resulting in strong stereo mismatch and nausea.
(edit: That bug where the right view is shifted a bit to the top also happen on windows, when activating the mentioned legacy mode for motion smoothing)

This second issue:

• Only occurs when an application is already running
• Only appears while the SteamVR overlay is visible
• Does not occur in the SteamVR Home interface

Expected Behavior
No headset-only screen tearing in SteamVR Home or applications
Correct stereo alignment in both eyes when opening the SteamVR overlay during gameplay

System Information:
Distribution: Arch Linux
Headset: Bigscreen Beyond 2e
GPU: Nvidia RTX 4070 SUPER
Driver version: 590.48.01
SteamVR version: (beta) 2.15.3

Additional Context:
Additionally, there is no option in SteamVR to change the headset refresh rate (Hz) from 90 hz to the possible 75 hz.
The Bigscreen Beyond Utility application is currently not functional on Linux, but this is likely unrelated and would most likely be upon Bigscreen themselves to fix.
(I've read about a kernel patch called "linux-bsb", but I did not try that.)

[triple-groove]

Issue 2 with the warped view can be solved with edit of: ~/.local/share/Steam/config/steamvr.vrsettings adding "enableLinuxVulkanAsync" : true to steamvr{}

   "steamvr" : {
.....
      "enableLinuxVulkanAsync" : true,
      "preferredRefreshRate" : 90,
      "supersampleManualOverride" : true,
      "supersampleScale" : 1.3244
   }

[trashhead101]

Yes. Thanks for this information.
I now know, how to fix both problems, after countless hours of try and error and some googling.

You can fix the screen tearing problem by disabling your other monitors except one. (I deactivated my second monitor and the tearing was gone.)
Weird, I know.

And as @triple-groove wrote, you have to set enableLinuxVulkanAsync to true (in ~/.local/share/Steam/config/steamvr.vrsettings). (!) But in in my case, I also had to set enableLinuxVulkanAsync to true in default.vrsettings (in ~/local/share/Steam/steamapps/common/SteamVR/resources/settings/). I'm also not exactly sure why.

I'm unsure, if I should close this bug report, because both solutions seem more like a workaround i.e. temporary fix instead of a real fix.

[trashhead101]

Sadly, now I have the problem, that I see older frames again after I've seen newer ones.
And also I sometimes have some weird static noise squares mostly in VRChat, but this is potentially a NVIDIA driver problem, as mentioned here: https://forums.developer.nvidia.com/t/bigscreen-beyond-hmd-unable-to-be-initialized-on-nvidia-possibly-due-to-dsc-bpp-issue/294108/66?page=3 (visible in the video in the 65th comment)