Librem 5 - Connecting to an external display using Display Port


just a short test report. It might be useful for someone.

Today I tried the following product with Librem 5:

A USB-C to Display Port converter including a Power Delivery function.
The idea was that using such set-up plus Bluetooth keyboard would eliminate the need for a docking station and would still charge the Librem 5 in convergence mode.

Unfortunately no video signal was detected by the external display so the test was unsuccessful and I immediately returned the USB-C to Display Port converter.

The power delivery was working and the Librem 5 was charging, but I did no measurements because without the video signal the converter is useless to me and this would have been just a waste of time.


I added your test to the wiki.


Was the external monitor detected by the Librem 5?

You should probably at least capture lsusb output before returning the device - for next time.

No, in the Settings it was not detected.

These results look rather similar to my test with a Fujitsu/Siemens port replicator.

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Die you see the “Thunderbolt 3” mentioning? The L5 supports usb-c display alternate mode, but not Thunderbolt.

The cable might well be a cheap alternative to the known-to-work dell Thunderbird dock to make the L5 multiplex a serial console to some lines of the usb-connector.


Hm, I ordered the adapter to look whether it would initiate thunderbolt alt mode, but I just found it working as a usb-c adapter cable to connect to an external display.

I changed the page to reflect my findings and added the information about my firmware. Maybe @Hristo needs to update to get it working, too.

The adapter is really nice since it seems perfect for presentations while travelling. Also it is quiet cheap when bought directly at the page of CABLEDECONN (at the time of writing 15US$ + shipping).

I also added a reference to the page to the information how to find the firmware versions used in the L5 that do influence docked mode.


Interesting finding. How could I update the firmware of the adapter?

First of all it would be very interesting which firmware versions are installed on your Librem5 :slight_smile: to check whether that has been the cause of our different findings.

About updating: First of all: if you update you can break things. If you do not know how to repair them you might need help to do so and you will not be able to blame support for having you told to update.

You can find information about the firmwares on the wiki page about troubleshooting docked mode. There is a reference to the repo of the TPS65982 firmware and information about the Display Port firmware.

Ah, I thought you mean updating the firmware of the adapter.
So you mean the firmware of Librem 5.

When I reflash the Librem 5 to the latest Byzantium release, is the firmware also getting updated?

I don’t think so: the firmware for the TPS65982 needs to be flashed to the chip (which seems to have an own storage not contained in the image).

For u-boot I can’t say without research.

But first things first: Find out your firmware versions and then you could think about a decision whether to update firmware(s) or not :wink:

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This is certainly true. However I updated the TPS65982 firmware on my phone and a) the update did work and didn’t break anything and b) it wasn’t that scary.

This exactly. This whole discussion is academic if the phone already has the latest firmware.

sudo cat /sys/kernel/debug/tps6598x/0-003f/customer_use

If you get 0x4c35445000000101 then you ought to update.

If you get 0x4c35445000000200 then I believe this is the latest (although I haven’t rechecked recently).

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I have this one.

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