DisplayPort MST regression with 570.86.16-2

Description:

This could be an upstream issue but as a beta stage driver was pushed to stable I thought that this might be useful info.

Upgrade from 565.77-4 to 570.86.16-2 broke DisplayPort MST functionality.

Setup is: RTX 4080 --(DP)--> Display 1 --(DP)--> Display 2

After upgrade only the last display in a DisplayPort daisy chain (Display 2) is showing output. All displays are detected but the hub display (Display 1) goes to standby at the display manager stage.

Displays are 32" 2160p Dell Ultrasharps.

nvidia-open-dkms is being used.

Display manager is SDDM and desktop is KDE Plasma using Wayland session.

Tested combinations of nvidia driver and kernel (with correct headers) versions:

• 565.77-4 and 6.12 -- working
• 565.77-4 and 6.13 -- working
• 570.86.16-2 and 6.12 -- not working
• 570.86.16-2 and 6.13 -- not working

Downgrade to 565.77-4 fixes the issue.

Additional info:

• package version(s): nvidia-open-dkms and nvidia-utils 565.77-4
• config and/or log files:
• link to upstream bug report, if any:

This has been a recurring thing after KVM toggles (display integrated) between desktop and laptop in the past but never at boot.

Steps to reproduce:

1. Upgrade nvidia-open-dkms and nvidia-utils to version 570.86.16-2
2. Reboot
3. Primary display (Display 1) goes to standby and does not recover on login.

Workaround:

sudo downgrade nvidia-open-dkms nvidia-utils lib32-nvidia-utils