DisplayPort doesn't work properly on Linux?

I don’t know enough to know if this is a Linux issue or a Linux+hardware issue, so I’m asking here too.

When I have DisplayPort hooked up to my dock, and my dock hooked up to my FW16, I try powering up the device. The displays don’t turn on (including the laptop display somehow). Only when I unplug the DP monitors does the laptop monitor work again, and then when I plug them back in, they work fine until the next boot.

HDMI does not do this.

Any ideas?

I noticed the same. Which dock do you have?
Using a WD19TB dock here.
What I also noticed, when hooked up to a 4K screen, I have often some stutters when moving screens around or changed virtual desktop fast. Seems a MUX switching issue (Automated MUX Switch in regular Desktop usage - stutter here and there - #9 by Jorg_Mertin).

Which dock do you have?
So you have the USB-C cable between FW16 and dock. Then displays plugged into the dock.
The dock then powers the laptop via the same USB-C, so don’t plug in any other power supplies to the laptop.
A majority of docks need some binary closed source software to make it work with the dock called “displaylink”.
Note, “displaylink” is pretty slow and no good for games etc.
A better solution is probably to purchase as many display port expansion cards as you need, and plug the monitors directly into the laptop, and not via a dock. That way, you will get full performance for games etc.
If your particular dock does not use “displaylink”, it probably needs some other driver to get it to work.

Well, through dock or expansion card DP, same thing.
You know that the DP expansion cards use USB-C too right?

The expansion card DP uses DP alt-mode. When in DP alt-mode the pinout is essentially turned into a DP port instead of a USB port.

If the dock is using thunderbolt, the usb port is essentially a PCIe x4 interface, so something in the dock will need to turn PCIe into Display port output, and that implies some sort of slow, low power GPU is needed in the dock. Thus a device driver is needed for that GPU.


Yo, that’s an awesome explanation, thank you! So does that mean though, that any dock specifically labeled thunderbolt will not work unless the dock manufacturer supplies a driver for Linux?

And that also means that any dock that’s specifically labeled USB-c will be using alt-mode?

There are several Thunderbolt docks that will work. You’ll just have to do research first. Its kind of like PCIE cards that are made by several vendors, but all share the same generic chipsets, then there’s some that use specialized chipsets that won’t work in Linux.

Think of Bluetooth and Wireless cards. Just because its made by ASUS or MSI doesn’t mean its not just the basic AX210 intel wireless chipset, but it could also be some really obscure realtek chipset thats flaky and runs poorly if at all on Linux.

@Nathaniel_Graham @Jerrod_Frost
As Jerrod mentions, its a bit difficult to tell whether a particular dock will work or not before you purchase it.
The usb ports on the FW16 are USB4 and should be compatible with Thunderbolt devices.
Its then a matter to trawling the various Linux forums to see whether a particular dock is compatible with Linux or not. That “compatibility” aspect is not Framework specific.

again, you don’t say which dock you have.

Makes sense, thank! My dock is the Lenovo Thinkpad Thunderbolt 3 Docking Station Gen 2. The dock post for the FW13 said it worked before, but that was a couple kernel versions ago, and Fedora 39 has issues with it (Linux 6.2.x I believe)

Yes, there was one version of the kernel that messed up DP/HDMI link negotiation for AMD GPUs. My particular problems was connecting it to a VEGA56 GPU. I forget which kernel version. It seemed pretty random as to which displays stopped working as a result. It is fixed in more recent kernels as far as I know, although I have not tested recently.

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