External monitor directly via USB-C

[Hmmm]

I have a LG 27UP850-W 4K monitor that has a usb-c connection on the back. It works via alternate dp over usb-c. I can connect my macbook or my Dell laptop with no issues via the single cable but steam deck is different.
When I connect the deck, the deck charges and also I can use the mouse and keyboard connected to the monitor. But no video or audio. There isn't any information in the deck settings as well.

Does anyone have experience in making this work or is this a hardware limitation? Maybe being fixed in a later update? I have tried stable and beta thus far.

OS 3.2; Build 20220526.1

[cubus]

The included Thunderbolt cable with my LG Ultrafine didn’t work. I bought a „USB C Cable to USB 3.1 Gen 2 Type C 10GBit/s with Video and Audio“ from Amazon and it worked.

[redlum]

Originally posted by cubus:

The included Thunderbolt cable with my LG Ultrafine didn’t work. I bought a „USB C Cable to USB 3.1 Gen 2 Type C 10GBit/s with Video and Audio“ from Amazon and it worked.

Interesting. Did the original cable supply power and peripherals but not video, or didn’t it work at all?

[Hmmm]

Originally posted by redlum:

Originally posted by cubus:

The included Thunderbolt cable with my LG Ultrafine didn’t work. I bought a „USB C Cable to USB 3.1 Gen 2 Type C 10GBit/s with Video and Audio“ from Amazon and it worked.

Interesting. Did the original cable supply power and peripherals but not video, or didn’t it work at all?

For me the supplied cable provides power and usb passthrough, no video or audio. Same cable works fine with MacOS or Windows laptops for example.

[pau]

I have the same problem with the same LG display. Originally, I also thought the Deck only had USB power in and data pass-through. When this works (I hope soonish), it will declutter a lot my setup, now I'm using an Anker USB hub connected to the monitor through HDMI, and changing inputs from MacBook and Steam deck is kind of painful.

[redlum]

I chased steam support and after several exchanges this was the final reply. In summary, please continue to chase for a fix Individually. The squeaky wheel gets the oil…


——————////
Hello,

Thank you for following up with us.

We don't have the data to confirm that a Steam Deck will connect to an LG 27up850 monitor in question correctly through the USB-C port.

Please be aware that Displaylink or Thunderbolt connection will not work directly from the Steam deck.

I'm forwarding your comments on to the appropriate department.

The Steam Deck team is actively working on making sure we can provide support for as many games, software, and peripheral options as possible. We're shipping frequent updates and fully expect Steam Deck's compatibility to grow steadily over time.

Additionally, if you wish to share an opinion, suggestion, or idea with the community as well, please visit the the Steam Deck Discussion forums.

This forum is regularly read by Valve's development team.

I apologize for any inconvenience this situation may have caused you.

[Boblin the Goblin]

Originally posted by redlum:

Originally posted by aerou:

Eizo EV3895 via USB-C here and no issues. Charging,video, audio,ethernet,all works and in 4K even.

The LG monitor owned by the OP and I does all this for seemingly every device (windows laptops, macs) except the Steamdeck, and never has. So maybe this is linux issue?

Sounds like it is Linux specific or something with the Dock's firmware.

[redlum]

When i run xrandr in Konsole (desktop mode) it says “DisplayPort-0 disconnected”

[Play]

For what it’s worth I’ve had no luck either. LG Ultrafine 4k. Tried various usb-c cables. I have managed to get audio but never video. Sorry, I know it’s not the purpose of the topic but what is the work around to connect to a monitor with only usb-c ports? I.e. with a dongle or hub?

[Waffelschmied]

Didnt work with the Lenovo Q24h-10. Using an alternative Anker USB-C-C-Cabel fixed the issue. Its Plug and Play now as i intended it when purchasing the Monitor.

[redlum]

Originally posted by Waffelschmied:

Didnt work with the Lenovo Q24h-10. Using an alternative Anker USB-C-C-Cabel fixed the issue. Its Plug and Play now as i intended it when purchasing the Monitor.

Interesting. Did you get power and peripherals from the old cable? What model was the anker?

[redlum]

Originally posted by Play:

For what it’s worth I’ve had no luck either. LG Ultrafine 4k. Tried various usb-c cables. I have managed to get audio but never video. Sorry, I know it’s not the purpose of the topic but what is the work around to connect to a monitor with only usb-c ports? I.e. with a dongle or hub?

I only have an Apple USB-C Digital AV Multiport Adapter to hand but it worked. Although it totally undermines the main benefits of USB-C though.

Note, I wouldn't recommend the Apple one as there are plenty of cheaper alternatives that will also do 60hz at 4K.

[redlum]

In the interest of raising the profile of this issue I thought I'd report some new findings...

Switched to desktop mode. Ran sudo dmesg -w in Konsole (after setting a user password in 'Users') then plugged in the usb-c cable from my monitor. Everything connecting as normal except for the below line:

[drm:retrieve_link_cap [amdgpu]] *ERROR* retrieve_link_cap: Read receiver caps dpcd data failed.

Based on discussions surrounding this error message, it appears to be an AMD GPU handshake issue under Arch Linux. Something to do with the External Display ID (EDID).

Can other users experiencing the OPs issue confirm that they are getting the same message in Konsole.

[redlum]

Another quick update for the LG gang - plugged in a USB-C to DisplayPort cable and a 4k 60Hz image appears on screen. No peripheral pass through, of course!

[Play]

Originally posted by redlum:

In the interest of raising the profile of this issue I thought I'd report some new findings...

Switched to desktop mode. Ran sudo dmesg -w in Konsole (after setting a user password in 'Users') then plugged in the usb-c cable from my monitor. Everything connecting as normal except for the below line:

[drm:retrieve_link_cap [amdgpu]] *ERROR* retrieve_link_cap: Read receiver caps dpcd data failed.

Based on discussions surrounding this error message, it appears to be an AMD GPU handshake issue under Arch Linux. Something to do with the External Display ID (EDID).

Can other users experiencing the OPs issue confirm that they are getting the same message in Konsole.

Ran the dmesg command but couldn't see the error you were referring to. Admittedly I'm probably at the limit of my technical understanding so not sure quite what to look for in the returned message. The monitor is referenced at least. Not sure if that is of any help.

[16911.349963] usb 1-1.4.1: New USB device strings: Mfr=3, Product=1, SerialNumber=0
[16911.349964] usb 1-1.4.1: Product: LG UltraFine Displa

[brianc266]

Originally posted by NEET_Guerilla:

Works fine with USB-C on my Samsung M7

I have a M7 and it doesn't work for me, you doing type c to type c ya ?