Regression in evdi 1.14.11: "Wrong edid size. Expected 256 but is 512" with DisplayLink 6.2 on Ubuntu 24.04

[Mike-Speedcracker]

Hi there,

I have a problem with the newest evdi driver (1.14.11) on Ubuntu 24.04:

When using DisplayLink driver 6.2 on Ubuntu 24.04 with evdi 1.14.11, external displays fail to work due to an EDID size mismatch. The kernel log shows the following error as soon as a USB-C docking station is attached:

evdi: [E] evdi_painter_connect:893 Wrong edid size. Expected 256 but is 512

As a result, no image is output on the external monitor.

This issue does not occur with evdi 1.14.10 - downgrading to that version restores proper functionality.

Environment:

• Ubuntu 24.04.3 LTS (Linux kernel 6.8.0-83-generic)
• DisplayLink driver 6.2
• evdi 1.14.11 → broken
• evdi 1.14.10 → working
• Hardware: USB-C docking station with DisplayLink chip (Lenovo ThinkPad Hybrid USB-C with USB-A / PN: 40aF0135EU), external monitor reporting 512-byte EDID (Samsung G9 Type).

Steps to reproduce:

1. Install DisplayLink 6.2 on Ubuntu 24.04, which includes evdi 1.14.11
2. Use evdi 1.14.11 (via DKMS or source build)
3. Connect docking station with external display
4. Observe dmesg:

[ +0,147920] evdi: [I] (card0) Opened by Task 76323 (DisplayLinkMana) of process 76279 (DisplayLinkMana)
[ +0,000982] evdi: [E] evdi_painter_connect:893 Wrong edid size. Expected 256 but is 512
[ +0,000004] evdi: [W] evdi_painter_connect_ioctl:1006 (card0)(pid=76297) disconnect failed

Expected behavior:
evdi should handle 512-byte EDID data correctly, as it did in 1.14.10.

Actual behavior:
evdi rejects the EDID and fails to provide output.

Workaround:
Downgrading to evdi 1.14.10 resolves the problem (DisplayLink Driver 6.1.1).

It would be nice to get a fix from you. :)

Regards,
Michael

[jakub-prussak-synaptics]

Hi, we'll take look at it, in the meantime could you collect the logs with DLSupportTool.sh and send them either here or to technical-enquiries@synaptics.com?

[Mike-Speedcracker]

Hi,

I’ve generated the DLSupportTool log as requested and sent it privately to technical-enquiries@synaptics.com, referencing this GitHub issue for context.
Please let me know if you need any additional information or specific test results.

Regards,
Michael

[jakub-prussak-synaptics]

It turns out that it's a regression with DLM itself not EVDI. For now you can use the latest EVDI with previous version of DLM and it'll work just fine, we will issue a fix for DLM later.

[Mike-Speedcracker]

Thanks for investigation.
I've installed the latest evdi 1.14.11 by using module/dkms_install.sh.
The combo of previous version of DLM and latest EVDI seems to work.

Regards,
Michael

[jakub-prussak-synaptics]

We released the new version with a fix for this, in short time it should be available in the repository.