Loss of multi-display support when using USB-C Travel Hub after suspend.

Submitted by Steven Ellis

Assigned to Intel GFX Bugs mailing list

Link to original bug (#111322)

Description

Hardware

• Lenovo T480s
  
• Lenovo USB-C Travel Hub
  
• Dell 24" Monitor
  

OS
- Fedora 29
- xorg-x11-drv-intel-2.99.917-42.20180618.fc29.x86_64
- Kernel 5.1.20-200.fc29.x86_64

I have a HDMI monitor, USB keyboard/mouse and network cable connected to the Lenovo USB-C travel hub at home.

Sometime when I connect this after the laptop has been suspended I get the following errors in the system log, and dual monitor support no longer works.

Aug 08 09:56:47 t480s kernel: [drm:intel_dp_start_link_train [i915]] *ERROR* failed to enable link training
Aug 08 09:56:47 t480s kernel: [drm:intel_mst_pre_enable_dp [i915]] *ERROR* failed to allocate vcpi
Aug 08 09:56:47 t480s kernel: [drm:intel_cpu_fifo_underrun_irq_handler [i915]] *ERROR* CPU pipe B FIFO underrun
Aug 08 09:56:47 t480s kernel: [drm:intel_mst_pre_enable_dp [i915]] *ERROR* failed to allocate vcpi

Once I've seen this error I can only run a single display
- Joined displays don't work
- Mirroring doesn't work

I'm still running Xorg due to some other Wayland issues and I can see the following in my logs when I try and enable my normal joined display

Aug 08 11:24:31 t480s /usr/libexec/gdm-x-session[2657]: (II) modeset(0): Allocate new frame buffer 3840x1200 stride
Aug 08 11:24:31 t480s /usr/libexec/gdm-x-session[2657]: (EE) modeset(0): failed to set mode: Invalid argument

Currently my only fix is to reboot the system.