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Old 08-08-2017, 12:58 PM   #1
FrodeJemtland
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Default Kubuntu 17.04, Dell 7480 and Dell D6000 universial dock, disconnecting randomly.

Kubuntu 17.04, Dell 7480 and Dell D6000 universial dock, disconnecting randomly.

I have a new Dell PC, Latitude 7480, connected to a DisplayLink dock named Dell D6000.

At first I had problems with the Intel driver, but managed to fix it with the tips found in the forums.

For the most part things are now working pretty good. There is one last thing that's not working as expected.

From time to time it seems the dock is disconnected, and reconnects, almost at once. The problem is that the external monitors usually stays "disconnected". They are shown in the administration tools for multiple monitors, but they goes to sleep, as if they do not have any signal.

As a fix I have to pull out the USB-C cable to the dock, and reattached it.

Thees "dropps" happens approx 3-10 times during the work day. Sometimes I can work the most of the day without anything happening, sometimes it can happen with only minutes apart.... And do that repeatedly. I can't find a pattern on when this happens, but I do have a hunch that it happens during things that are visually intensive. Scrolling fast on a web page, watching video. Not sure this has anything to do with it, just a hunch.


I have search through the BIOS for any USB values, but can't find any that is of interest for this problem.

I have worked through the post "How to fix your DisplayLink product from repeatedly disconnecting and reconnecting or freezing". But there is a some of the alternatives that has no options in Linux.
1. CHECK IF YOU HAVE THE LATEST DISPLAYLINK SOFTWARE INSTALLED
OK, have 1.3.54.
2. CHECK IF YOU HAVE THE LATEST USB 3.0 HOST CONTROLLER DRIVER INSTALLED ON YOUR PC.
Running kernel Linux-4.10.0-30-generic-x86_64, so I suppose this is where the latest USB 3.0 host controller driver is....
3. CHECK IF YOU HAVE THE LATEST USB HUB FIRMWARE PROGRAMMED ON YOUR PRODUCT
I can only find a Windows driver on Dell's driver download page. No firmware or similar.
4. CHECK IF YOU HAVE THE LATEST BIOS VERSION INSTALLED ON YOUR PC.
I had the 1.4.6 BIOS, but when I upgraded to 1.5.2, the screen flikkered a lot. This behavior disepaired after changing from Modsetting to Intel driver for Xorg.
5. CHECK IF THE SAME BEHAVIOUR IS SEEN WHEN CONNECTED TO A USB 2.0 PORT ON YOUR PC (OR IF NONE IS AVAILABLE WITH A USB 2.0 CABLE)
Do not think I have a 2.0 port on my PC. I'm not sure how to connect a 2.0 USB cable to the Dock, as the USB-C cable is not detachable on the dock.
6. CHECK IF THE SAME BEHAVIOUR IS OBSERVED WITH A DIFFERENT USB CABLE OR USB PORT
See response on point 5. I have also tried to use the non USB-C dongle (Standard USB port), but not sure what I actually is testing by doing so... Problem still excists.
7. TRY A USB 'Y' CABLE (IF YOU ARE USING A USB POWERED MONITOR PRODUCT)
This I have not tried. What is a USB Y cable? We do not have thees at work.
8. TRY CONNECTING YOUR PRODUCT THROUGH AN EXTERNAL MAINS POWERED USB HUB
This I have not tried. Have tried to connect both the D6000 and the PC to separate power cables.
9. DISABLE USB SELECTIVE SUSPEND
Can't find this as a option on Linux, but have tried to sett the usbcore.autosuspend
Tried to sett usbcore.autosuspend=-1 and ausbcore.autosuspend_delay_ms=-1. (should use this last one for Ubuntu versions above 15.03, it seems)
No effect. What speaks against this is that this "dropps" happens when I'm actively working. I have never noticed that it has happened if the machine is not used. It's always OK in the morning, like I left it for the night.

Anyone that has a suggestions for what to try next?

ATTACHMENTS:
HIKT-E7440-LTS_2017-08-08T11:44:07.884309.zip
DLSupportTool file while everything is OK.
What was I doing while this crash happened? Nothing, no crash.

HIKT-E7440-LTS_2017-08-08T13:17:34.473771.zip
DLSupportTool file right after a "dropp". Monitors re-enabled by them self.
What was I doing while this crash happened? Scrolling (with the mouse) on the forum pages of DisplayLink, in the Chrome web browser.

HIKT-E7440-LTS_2017-08-08T13:44:27.775765.zip
DLSupportTool file right after a "dropp". Monitors did now stay disabled.
What was I doing while this crash happened? Was scrolling down a web page with the down arrow on the keyboard.

Last edited by FrodeJemtland; 08-08-2017 at 02:00 PM.
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Old 08-25-2017, 11:50 AM   #2
FrodeJemtland
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Default

Anyone have any idea or tips of anything to try out?

It's still immensely annoying. Have to pull out an plugg inn the USB C cable 5-10 times a day, and the monitors turn off at the most annoying times...
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Old 08-25-2017, 02:22 PM   #3
Toto
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Default

Hello !
I also have a D6000 dock and it seems to happen less frequently when I plug it with USB3 cable. The dmesg log suggest that it may be a power management issue. Indeed, it seems that the kernel tries to suspend all the devices plugged in the dock. I haven't found a solution yet, unfortunately.
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Old 09-11-2017, 03:01 PM   #4
FrodeJemtland
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Default

Tried to upgrade to the last BIOS for my machine. Dell 7x80 v 1.5.8.

The kernel has also been upgraded to 4.10.0-33-generic

Still have the same issue. Not that hard to reproduce. Just watch a Youtube clip. I'm feeling lucky if I can watch it to the end.

In addition the last couple of days I have also experienced that the external monitors some times is not detected. It might be if they are not connected at a reboot. That is a new effect that is not wanted
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Old 10-04-2017, 05:05 PM   #5
blaise64
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Default Same Problem

I have the exact same problem with the same dock and a similar laptop (latitude 7280).
I tried several power management config but it failed and i have tried all the proposed solutions in your post (upgrade etc...) without success.

I have a windows dual boot that works fine with same monitor and same dock, cable etc... so i know it is not a hardware failure (except maybe a firmware problem).

The big problem with plugging/unplugging is that some random time it will not reset properly and my windows are split between two screen and all become freezed...

The os is a Linux Mint (Ubuntu 16.04 LTS based).

Does anyone have a working D6000 on linux or another usb-c dock that work under Ubuntu like OS ? If I can't make this dock work i will be happy enougth to bougth another dock if i allow me to not besome insane...
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Old 10-09-2017, 08:43 PM   #6
FrodeJemtland
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Default Can some of the problem be a possible power issue?

I have for this setup a 240W power adapter. I have thought that bigger is better, but it might actually be one of the reasons the problem is so severe.

I noticed that the problem is triggered, when the CPU starts to work. As I wrote in a earlier post, the problem is connected to doing something graphic intensive, like watching a video.

I was questioning someone from work what kind of power supply we usually deliver whit the D6000 dock, and that is 130W. Just for the test of it I replaced the 240W with a 130W, and that resulted in a big improvement. I still have the problem, but maybe only 1 out of 10 times, compared to before the switch....

That was strange.... Doing some more tests.

---- Edit after a week.
This did NOT fix the problem....

Last edited by FrodeJemtland; 10-17-2017 at 09:21 AM.
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Old 10-12-2017, 01:36 PM   #7
Jérémie
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Default same problem

I have exactly the same problem on my dell latitude 7480. Nobody found a solution ?
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Old 10-13-2017, 08:34 AM   #8
pbeutier
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I can confirm the 1.4 release dont fix this bug...
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Old 10-26-2017, 10:46 AM   #9
FrodeJemtland
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Default Upgrading Kubuntu

Testet upgradeing Kubuntu to 17.10 hoping this might have a positive effect, to no avail.

Testet another pc, with Kubuntu 17.10 on the same dock and monitors. There everything seemed to work OK.

Not sure what is the big difference, but looking into the graphic card, and drivers/kernel modules.
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Old 10-27-2017, 09:37 AM   #10
FrodeJemtland
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Default A fix that might have something to do with this

Hi

After I upgraded to 17.10, my mouse is a bit sluggish, so I have searched around for a solution to this. I found a reddit post:

--
Pxxrpsy
There is a reported problem with the kernel 4.13 and some Intel graphics. My computer was crashing constantly and I was blaming Plasma, but it was the parameter intel_iommu that has been enabled by default in 4.13. Try to set the kernel parameter intel_iommu=off and hopefully it will help.
--

This was verry interesting regarding my problem with the external monitors that is being disabled.

I now have kernel version 4.13, so I turned intel_iommu to off, two days ago. I have manged to force the problem only one time after this. The problem do not appear while I sit at the computer, anymore. I have noticed that the external monitores is turned off, a couple of times, if I have left the machine for a couple of hours.

I do still have a sluggish mouse, and the CPU is going through the roof when the screensaver has been running for a couple of minutes... But I think this is related to the upgrade from 17.04 to 17.10.

I'm immensely interested if anyone else with this problem do see effect by changing this option.

To change it if you are on ubuntu/debian, edit your /etc/default/grub, and add intel_iommu=off to the GRUB_CMDLINE_LINUX_DEFAULT line. Then update grub by running update-grub2.
Reboot.

If you try this, please report back if this has helped you, and if the problem has been just reduced, or completely fixed....


-- Edited 2. nov., after a week, with this fix.

This is strange. Once again I see improvement right after the change has been done, but after a day or two the error is back. And I'm back to square one.....

Last edited by FrodeJemtland; 11-02-2017 at 08:37 AM.
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