with kernel 4.8.1 on linux (archlinux testing branch)  the tb15 dock works fairly well (even with 4.7.x).
de-activating WIFI helps.

issues that remain:
- it takes a rather long time until linux initializes everything (10+ seconds) so you need patiences. definitly not a OS X type of experience
- when using a 4k screen it much depends on the cable and the mini display port seems to be no good. using the HDMI or better the DP port works much better
- network adapter stops working after some time (i solved it by using an attached usb adapter)

if someone finds a way to re-activate the network drive please let us know. (i haven't tried re-loading the module yet).

I'm being given the option of a refund. I'll likely take it, and buy a D3100 which has official Linux support, and 4K compatibility. It doesn't charge the laptop, so will need to run two cables, but the recent DisplayLink drivers have been working well, so it should work. I'll use that until the thunderbolt revolution actually happens (maybe next year). As of now, I can't justify the £300+ price point of the TB15. 

This weekend, I upgraded my Precision 5510 to Ubuntu 16.10. The included kernel version is 4.8.0-26. I haven't yet been able to flash any firmware upgrades to the TB15, because AFAIK there is no mechanism for this without installing Windows on the 5510.

In any case, the dock is mostly functional, at least for my needs. It drives a sub-4k wide screen monitor through HDMI, enables USB mouse and keyboard, as well as connecting a USB external drive. While everything seems a tad bit more stable under 4.8, the one issue that didn't resolve is the inability to cold boot with dock attached. When I connect USB-c umbilical and start the machine, the USB mouse and keyboard are not recognized (HDMI screen does start up though). The only way I can get the dock to operate USB mouse and keyboard is to boot the machine, wait until after I enter the LUKS pass phrase, and then attach the umbilical. Then there is a slight 10 sec delay, and the USB mouse and keyboard come alive.

Is there anything else I need to do in order to make everything work under a cold boot? If the dock firmware needs to be flashed, how can that be applied without installing Windows on the 5510? I tried doing it from my Windows VM, but the dock itself is not recognized, and I don't feel comfortable flashing the dock from a VM anyhow. Have others been able to address the cold boot issues?

SIDE NOTE:

What's with the Google reCAPTCHA on the forum? I have to re-enter it literally every 30 seconds. Seems it's configured a bit too aggressively.

EDIT:

I just tried a test to ensure I had the appropriate modules enabled for my initramfs so that early USB HID devices would work during cryptsetup. Indeed, removing my USB keyboard from the dock and plugging it directly into the laptop worked fine, so that does seem related to the dock's cold boot issues.

-sk3l

Barton George, DELL-Jared D, DELL-Justin C: do you have an update on this issue?

According to my Windows (dual boot) Dell update software my drivers and my Bios are up to date on my Dell XPS 9350 and the TB15.  The TB15 is still paperweight for me. Only the external screen is working, everything else is not available. Kernel version: 4.8.6

At this point, if your TB15 dock is working at all, much less with limited functionality you are probably the exception. It's well documented that there should be no expectation for the dock to work and that it should be returned ASAP.

If you are determined to keep trying, the latest mainline kernel is what you should be using. However, as you are finding out. The odds of the dock working are not good regardless of what software environment it is used with.

As it has been stated before, you should return the dock and wait for it to be re-released.

I thought the Dell team said they were working on xps 13 support and that they were going to fold changes into the kernel upstream in most cases and firmware updates where needed? We also needed to wait for intel to work on the display drivers so if we did do multi-monitor it would much better--the latest changes in 4.9 really helped. There are also intel wireless driver issues because I have to remove the driver from the suspend process and load it later to make suspend work.

I have the xps 9350 and the TB15 works for most things but it is quirky under linux.  Sound does not work yet. Dual monitors work fine for mDP and HDMI. The broadcom wireless card seemed to cause issues for me but now I'm intel. I have to boot without the dock plugged in.

I've got several wires going into the dock and only one wire into my computer so that works for me.

They're talking about re-releasing the dock since almost one year, but is there any real ETA, even an estimated one?

It seems like the Dell team has been good about getting drivers merged into the mainline kernel. As far as the linux kernel support, I think we're getting there. Although, I think it's mostly Intel that is getting the thunderbolt 3 drivers merged. My dock was working relatively well with Ubuntu running mainline kernel. I know I documented what was working/not working and what kernel version I was using earlier in this thread.

The issue isn't so much driver support anymore. It's hardware/firmware issues with the dock itself. That's fortunate that your dock seems to be working for the most part. Mine was going strong and then suddenly stopped working.

I seem to recall it supposedly being available again this year. However, I'm not holding my breath. In the mean time I have a 2xdisplayport thunderbolt adapter, usb3 ethernet adapter, and a usb3 usb hub. It's messy and not very sleak but it's getting the job done well enough.

Thunderbolt 3 is still pretty new. There's not much in the way of docks available. None that promise to work with linux. So, I'm willing to be patient with Dell and wait for them to get it right.

Let's just hope Dell do a proper recall and exchange ALL the faulty TB15, bought directly from them or from a third-party.

All I did was contact Dell support. They were very helpful even though I bought it through Amazon.

> As it has been stated before, you should return the dock and wait for it to be re-released.

Do you know/can you provide any link to an official dell website confirming your information? I already did a web search about how to return the TB15 but couldn't find anything.

The dock doesn't work well even on Windows, they said it's an hardware problem so we will have to wait for a new version.