Summary
Working dual-monitor setup on a Dell Universal Dock UD22 (DisplayLink hybrid) after installing Synaptics DisplayLink + EVDI. Documenting symptoms, false leads, and the hybrid connector layout so others (and #549) can compare.
Without DisplayLink/EVDI, the dock partially negotiates DP-MST via i915, which looks like a GPU/driver bug (blank monitor + flashing / stuck at 640×480).
Hardware
| Item |
Detail |
| Laptop |
Dell XPS 15 9570 (Intel UHD 630 + NVIDIA GTX 1050 Ti) |
| Dock |
Dell Universal Dock UD22 |
| USB IDs |
413c:f6d0 (Universal Dock UD22), 17e9:6013 (DisplayLink Dell Universal Hybrid Video Dock) |
| Monitors |
2× ASUS PA278QV (2560×1440), one landscape / one portrait |
Software
| Item |
Detail |
| OS |
Pop!_OS 24.04 LTS (COSMIC / Wayland) |
| Kernel |
7.0.11-76070011-generic (System76) |
| displaylink-driver |
6.3.0-48 (Synaptics APT) |
| evdi |
1.15.0-193 (DKMS, built cleanly on this kernel) |
Symptoms before DisplayLink
- One external monitor blank
- Other external monitor flashing / stuck at low modes (compositor showed only ≤1024×768, preferred 640×480)
- Dock USB devices present (
lsusb showed DisplayLink), but no evdi module and no displaylink-driver package
- Kernel DRM showed
card0-DP-* connectors from i915 with valid EDIDs
- dmesg / journal included MST failures, e.g.:
Failed to read DPCD registerfailed to lookup MSTB with lct 2, rad 60
This is easy to misdiagnose as an Intel/NVIDIA driver problem. The Windows side worked because DisplayLink drivers were present there.
Fix
- Install Synaptics APT keyring +
displaylink-driver (pulls evdi DKMS).
- Confirm
evdi is loaded and displaylink-driver.service is active.
- External outputs appear as EVDI
DVI-I-* nodes (plus, on this hybrid dock, one monitor may remain on an i915 DP-* connector).
After install (stable):
DVI-I-1 (EVDI / DisplayLink): ASUS PA278QV @ 2560×1440DP-5 (i915): second ASUS PA278QV @ 2560×1440 (portrait via compositor transform)- Laptop
eDP-1 still available
Ubuntu’s prebuilt linux-modules-evdi-* packages did not match this Pop/System76 kernel ABI; Synaptics evdi via DKMS worked.
Hybrid dock note
UD22 advertises as a hybrid DisplayLink dock. In practice we saw both:
- Native DP-alt/MST sinks on
i915 (DP-*)
- EVDI sinks (
DVI-I-*) once DisplayLink userspace was running
Driving dual QHD through MST alone was unreliable; once DisplayLink was installed, the flaky MST sink went away and both panels ran at native 1440p.
Relation to #549
Issue #549 reports UD22 on Ubuntu 24.04 with a second monitor still blank after installing drivers. Possible checks for that case:
- Confirm
lsmod | grep evdi and systemctl status displaylink-driver (or equivalent)
- Look for both
DVI-I-* (EVDI) and leftover DP-* (i915 MST) connectors
- If only one EVDI connector is connected, try
options evdi initial_device_count=2, cable/port swap on the dock, and whether one panel is still bound to a broken MST connector
- On custom kernels, prefer Synaptics/DKMS
evdi over distro prebuilt modules that target a different kernel package
Happy to provide more logs if useful. This is primarily a success report + troubleshooting fingerprint for UD22 / hybrid docks.
Summary
Working dual-monitor setup on a Dell Universal Dock UD22 (DisplayLink hybrid) after installing Synaptics DisplayLink + EVDI. Documenting symptoms, false leads, and the hybrid connector layout so others (and #549) can compare.
Without DisplayLink/EVDI, the dock partially negotiates DP-MST via i915, which looks like a GPU/driver bug (blank monitor + flashing / stuck at 640×480).
Hardware
413c:f6d0(Universal Dock UD22),17e9:6013(DisplayLink Dell Universal Hybrid Video Dock)Software
7.0.11-76070011-generic(System76)6.3.0-48(Synaptics APT)1.15.0-193(DKMS, built cleanly on this kernel)Symptoms before DisplayLink
lsusbshowed DisplayLink), but noevdimodule and nodisplaylink-driverpackagecard0-DP-*connectors from i915 with valid EDIDsFailed to read DPCD registerfailed to lookup MSTB with lct 2, rad 60This is easy to misdiagnose as an Intel/NVIDIA driver problem. The Windows side worked because DisplayLink drivers were present there.
Fix
displaylink-driver(pullsevdiDKMS).evdiis loaded anddisplaylink-driver.serviceis active.DVI-I-*nodes (plus, on this hybrid dock, one monitor may remain on an i915DP-*connector).After install (stable):
DVI-I-1(EVDI / DisplayLink): ASUS PA278QV @ 2560×1440DP-5(i915): second ASUS PA278QV @ 2560×1440 (portrait via compositor transform)eDP-1still availableUbuntu’s prebuilt
linux-modules-evdi-*packages did not match this Pop/System76 kernel ABI; Synapticsevdivia DKMS worked.Hybrid dock note
UD22 advertises as a hybrid DisplayLink dock. In practice we saw both:
i915(DP-*)DVI-I-*) once DisplayLink userspace was runningDriving dual QHD through MST alone was unreliable; once DisplayLink was installed, the flaky MST sink went away and both panels ran at native 1440p.
Relation to #549
Issue #549 reports UD22 on Ubuntu 24.04 with a second monitor still blank after installing drivers. Possible checks for that case:
lsmod | grep evdiandsystemctl status displaylink-driver(or equivalent)DVI-I-*(EVDI) and leftoverDP-*(i915 MST) connectorsoptions evdi initial_device_count=2, cable/port swap on the dock, and whether one panel is still bound to a broken MST connectorevdiover distro prebuilt modules that target a different kernel packageHappy to provide more logs if useful. This is primarily a success report + troubleshooting fingerprint for UD22 / hybrid docks.