Arch Linux

wackba

Member

Registered: 2017-06-13

Posts: 4

USB-C to DisplayPort on T495

I bought a new T495 with an AMD Ryzen 3500U Pro and Vega 8 graphics. I have i3 and amdgpu installed and managed to get everything working (gaming on steam works too) -- except connecting an external monitor over USB-C. The connection is working when booting Windows from an USB stick, so it has to be a software problem related to Linux.

The output of dmesg is when plugging in:

[  590.186860] [drm] DM_MST: starting TM on aconnector: 00000000860932f7 [id: 71]

and when unplugging:

[  749.663437] [drm] DM_MST: stopping TM on aconnector: 00000000860932f7 [id: 71]

Nothing else changes. lsusb -t gives

/:  Bus 05.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/1p, 10000M
/:  Bus 04.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/2p, 480M
    |__ Port 1: Dev 2, If 1, Class=Wireless, Driver=btusb, 12M
    |__ Port 1: Dev 2, If 0, Class=Wireless, Driver=btusb, 12M
    |__ Port 2: Dev 3, If 0, Class=Hub, Driver=hub/3p, 480M
        |__ Port 1: Dev 4, If 2, Class=Video, Driver=uvcvideo, 480M
        |__ Port 1: Dev 4, If 0, Class=Video, Driver=uvcvideo, 480M
        |__ Port 1: Dev 4, If 3, Class=Video, Driver=uvcvideo, 480M
        |__ Port 1: Dev 4, If 1, Class=Video, Driver=uvcvideo, 480M
        |__ Port 2: Dev 5, If 0, Class=Chip/SmartCard, Driver=, 12M
/:  Bus 03.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/4p, 10000M
/:  Bus 02.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/4p, 480M
/:  Bus 01.Port 1: Dev 1, Class=root_hub, Driver=ehci-pci/1p, 480M

and is not changing at all.

I tried installing linux-git from the aur, but the problem remained unchanged. Am I missing some drivers or is this hardware feature currently not supported in Linux? Any suggestions?