Lenovo Yoga + Lenovo TB dock: displayport monitors via dock don't work, "Link Training Unsuccessful" errors
i915 doesn't manage to display anything over monitors connected via displayport to a Lenovo TB dock.
System info:
- architecture: x86_64
- kernel: 5.12.0-rc2-drmtip (built from commit 249f72def27bf994655d of drm-tip branch)
- distro: Ubuntu 20.04.2 LTS ("focal")
- machine: LENOVO ThinkPad X13 Yoga Gen 1 (BIOS rev 1.30)
- dock: Lenovo ThinkPad Thunderbolt 3 Dock Gen 2
- display connector: dock connected to laptop via TB3; the dock has 2 DP outputs, each of which is connected to a Dell U2719D monitor
(This is the same system as for issue 3221, but I thought I'd try with an external dock rather than the usb-c-to-dp/dp-daisychain scenario. Turns out it's even less functional :-))
When the laptop is booted connected to the dock, it does not manage to send any output to the displayport-connected monitors. On the console there are numerous reports of "ERROR Link Training Unsuccessful".
I'm attaching the (6.6MB) kern.log of a bootup-and-shutdown (made with "drm.debug=0x1e log_buf_len=1M"). Happy to provide further info/do other tests as required. dock-kern.log