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fullonuts

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10 years ago

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fullonuts

15 Posts

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August 16th, 2016 10:00

Dell XPS 13 9350 + Linux + Thunderbolt 3/USB-C

Hi all. I've been following these forums for a few weeks hoping to find a solid solution to my problem. Through my searching and browsing, it seems like there are numerous people mentioning the same or similar issue, but so far I can't seem to find any concrete solutions or knowledge from the community or from Dell. I'm hoping this post is more on-topic and provides more detail for the issue so we can better diagnose it and find a solution.

First though, the issue. I'm running the 2016 Dell XPS 13 9350 with an external Dell 4K monitor (P2415Q) using the USB-C/Thunderbolt 3 output with an adapter to mDP. I'm running Ubuntu 16.04 with 1.4.4 BIOS, and 4.7 mainline kernel. All drivers were updated as of two weeks ago prior to wiping Windows and installing Linux.

The external is recognized (i.e., it shows up in both xrandr and in Display settings) but the picture never remains. It will appear briefly, maybe for a few seconds or so, but then the screen goes black. I'll add that the external doesn't turn off (or go to sleep), but it doesn't display anything and is still shown in settings.

I've read that this could be related to ACPI power modes, namely RC6 with Skylake processors. I've tried appending a line to my kernel to disable RC6 entirely, but that doesn't seem to work. Along these lines, I've also read that this does fix some instances and this patch will be included in the 4.8 mainline kernel update (it's in RC2 right now, so soon?).

Admittedly the adapter I'm using is a $20 "cheapo" from Amazon, though the vendor does say it supports 4K at 60Hz (but I guess vendors can say whatever they want). I've been hearing positive things about Google's adapter, but don't want to shell out the $40 until I've narrowed the problem to the adapter. From the numerous other posts from folks using various adapters all whom are experiencing the same issues, I'm led to believe the adapter isn't the culprit.

I've also read that there could be some conflict with the wireless adapter, and that reducing its power stabilizes things. Unfortunately, reducing the power of my wireless adapter does not fix the issue, and even if it did, it is a suboptimal solution as it slows my connection considerably.

Some questions I'm hoping to get answers for are:

* is this a known issue and are my experiences on par with others, or are things slightly different?
* does Dell know about this issue, and are they working on a solution? I'm totally OK waiting for a solution, it'd just be nice to know one was being actively worked on
* is there a problem with the hardware? Is this Dells problem and I should return my device?
* is there some hidden driver update out there that fixes this issue (that's for Linux, not Windows)?
* has anyone found a temporary solution that does work?

I would like to scope this conversation to linux operating systems using external displays via the USB-C/Thunderbolt 3 connector, to hopefully keep it on-topic.

Thank you all in advance. I hope this thread proves useful to many.