6 Posts
6
39732
XPS 13 9300 and WD19TB linux problem
Hi everyone,
I have some trouble with my Dell XPS 13 9300 and the WD19TB thunderbolt dock.
At the time I bought the notebook there was no developer editon available here in Germany so
I installed Ubuntu 20.04 myself with dual boot. The notebook itself works like a charm. But the WD19TB keeps troubling me:
- The external monitors work only if they are connected at boot time. Later connecting thunderbolt to the running system does not give me a signal on the external monitors.
- Even if the dock is connected at boot time the external monitors often lose the signal, went black and never come back. Connected USB devices like keyboard and mouse will come back and can be used after some seconds. I need to reboot the system to get my external monitors to work again.
On some days I can use the external monitors for hours without problem, on others I can barley use them at all.
If the monitors disconnect the following message is found in the system log:[drm:intel_cpu_fifo_underrun_irq_handler [i915]] *ERROR* CPU pipe B FIFO underrun
I tried the following: Disable Monitor Sleep, Disabling CPU sleep modes, Newer Kernels (5.4.x up to the newest 5.6.x), even other linux distros via live USB. All had the same problem. I also tried a different WD19TB and using the other thunderbolt port on the XPS.
Under Windows there are no such problems, everything works like a charm. But I can't do my work there.
Bios and WD19TB Firmware are the lastest versions available from Dell
Thanks for reading, any help appreciated
bulletmark
47 Posts
6
October 25th, 2020 17:00
Guys, after much research and trial and error, I have found a simple solution so the WD19TB dock works perfectly on Linux, with zero issues!
To reiterate, my system is:
- Dell XPS 13 9300 (i7-1065G7 CPU, early 2020 model)
- Dell WD19TB Thunderbolt 3 dock (with ethernet + audio + nearly all USB ports in use)
- Two Dell 2560x1440 screens (each accept either DP or HDMI input)
- Running GNOME + Wayland on Arch Linux (which is currently Linux 5.9.1, GNOME 3.38.1)
- Linux kernel boot options: `mem_sleep_default=deep i915.enable_guc=2`
- BIOS version 1.2.0
- Intel microcode version 0xa0[160] (for i7-1065G7 CPU, need at least
0x96[150] to overcome Jetbrains IDE problem, see https://youtrack.jetbrains.com/issue/JBR-2310)
The problems I have been experiencing include:
- One or both displays would not turn on after returning from screen standby, or system suspend. Happens using either the DP or HDMI connections, with 1 screen connected, or 2.
- Display connection and re-connection is "glithy", often flashing a few times and I was never confident the display/dock would re-connect at all.
- The most serious problem is that sometimes, in the middle of use and more often when the machine is busy, the dock connected screens black out for a short time. When this happens there is nothing in the journal. Other times (often, not long after the screens recover from a blackout), the entire dock fleetingly drops out and you see all the USB etc disconnect/reconnect logs in the journal. Seems to be a problem with Ice Lake CPU and WD19TB, see https://gitlab.freedesktop.org/drm/intel/-/issues/1453.
I suspect all these problems, are due to a bug in the implementation of DisplayPort (DP) Multi-Stream Transport (MST). So the work-around is simply to disable video MST, i.e. add Linux kernel boot option `i915.enable_dp_mst=0`. Adding this option prohibits the dock to drive more than 1 screen via DP (or HDMI) so I bought a cheap ($12 USD) Thunderbolt3/USB-C to DP adaptor/cable from which I drive the other screen. That cable plugs in to the daisy chain thunderbolt/USB-C connector on the back of the dock. So I still drive 2 displays from the dock, and all the USB ports and audio, via the single cable from the dock to the laptop.
Note that just running a single screen from the dock (using DP or HDMI) is not sufficient, you will still get blackouts/disconnects on that single screen unless you disable MST. Note, various USB-C to HDMI adaptor/cables are flaky with the XPS 13 9300 (e.g. even after BIOS 1.2.0 mine does not work) so I suggest it is best to use a Thunderbolt3/USB-C to DP cable as I did.
After adding the `i915.enable_dp_mst=0` option, I have not had a single problem using the dock for more than a week and am very happy with it.
bbox
2 Posts
0
October 27th, 2020 09:00
Thanks alot!
I had suspected, that MST is actually the issue and bought a DP Adapter to attach it to the Thunderbold port on the backside of the dock, but this didn't help at all.
That i am able to completely disable this feature kernel wise was new for me and is working the whole day now. Before i couldn't use the dock for 5 minutes straight.
I bought Dell-only hardware including the developer XPS, because it was suppose to work out of the box - i really hope, that Dell is fixing that. Otherwise i must discourage my company to switch to dell for development.
samuelgrigolato
4 Posts
0
October 27th, 2020 11:00
Hey, that's wonderful!
Even though I had some luck switching to Sway/Wayland (not sure why as everybody seems to be using Wayland already and still having issues) I was really missing my previous i3 setup.
I applied the kernel parameter and so far it is working glitchless. Thanks for sharing your research results :).
Clueless1969
1 Message
0
October 29th, 2020 03:00
Disabled MST and no glitches anymore. Thank you very much. But I like three monitors and have the 9300. So all my USB c ports now are filled.
I think the "Dell Universal Dock D6000" does not use MST and so should probably work fine. Do you think that will also be a solution? A bit of a waste of my WD19TB but having a single cable going into my laptop might be worth to replace it...
And obviously the D6000 uses Display Link what is very slow for video.
ThornleyD
11 Posts
0
November 6th, 2020 13:00
Hi @bulletmark
I have a Choetech USB-C thunderbolt 3 to DP cable and found that it is still unstable with the WD19 and dp_mst disabled in Linux (with wayland). In fact, it is also unstable in Windows with this configuration.
Can you please supply a link to the cable you purchased?
Thanks, David.
bulletmark
47 Posts
0
November 6th, 2020 14:00
@ThornleyD that is the same cable I purchased. You say you have "dp_mst" disabled. Are you sure you set i915.enable_dp_mst=0 correctly? Please paste the output of `cat /proc/cmdline` here.
If you are using early KMS then you need to set `options i915 enable_guc=2 enable_dp_mst=0` in `/etc/modprobe.d/i915.conf`.
bulletmark
47 Posts
0
November 10th, 2020 04:00
@ThornleyD 4 days to reply and what about my second statement? Are you using early KMS? If so you need that other setting. Also, what exactly mean when you say "unstable"? If that cable does not work in Windows then surely either the cable is faulty or there is something else fundamentally wrong. I have lived with daily annoying issues until I set that `i915.enable_dp_mst=0` option but now 3.5 weeks later, the dock is pretty much perfect.
ThornleyD
11 Posts
0
November 10th, 2020 04:00
/proc/cmdline is "BOOT_IMAGE=/boot/vmlinuz-5.6.0-1032-oem root=UUID= ro i915.enable_dp_mst=0 quiet splash vt.handoff=7"
ThornleyD
11 Posts
0
November 10th, 2020 05:00
Not suggesting it wasn't working for you, but it isn't for me, others have confirmed your suggestion improves stability.
No early mode setting, mine is stock ubuntu 20.04, the only change is the oem kernel and wayland.
Since I have started to experience issues with WD19 under Windows also, I suspect there is an issue with my hardware setup (it is all Dell equipment and under warranty). The dock is working fine with a 7390 XPS13 though, so I am concerned it is an underlying issue with my 9300.
Have been sick with bonafide flu last few days...
pointo1d
3 Posts
0
November 10th, 2020 05:00
TFT @unwinds - running Ubuntu 20.04, it really was that simple for me - many thanx for the heads-up.
bulletmark
47 Posts
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November 10th, 2020 14:00
You say "others have confirmed your suggestion improves stability". Two others have responded here to my post. One said "it is working glitchless", the other said "no glitches anymore". That is better than merely "improves stability".
You also say "the dock is working fine with a 7390 XPS13". The 7390 is an Ice Lake machine the same as the 9300 and has had the same reports of problems with the WD19TB, e.g. here and here. Possibly you have not tested it well enough.
ThornleyD
11 Posts
0
November 11th, 2020 04:00
'Improves' is relative, if it is indeed to perfection, so be it
It is possible there is something else going on, I have had the 9300 repaired (display and top chassis were replaced) and it hasn't been the same since.
I agree, it needs some more testing. Thanks again for the help!
evanzel
6 Posts
0
November 11th, 2020 05:00
FYI, BIOS 1.3.0 mentions fixes for WD19/WD19TB
bulletmark
47 Posts
0
November 11th, 2020 14:00
Today's new BIOS 1.3.0 update does mention some WD19 fixes but unfortunately doesn't specifically mention the random dock blackouts/disconnects which is by far the most serious problem. I have applied the new 1.3.0 BIOS, removed the `i915.enable_dp_mst=0` option, and have placed my 2 screens back on DP connections. I will report here in 1 week if it looks good.
bulletmark
47 Posts
1
November 11th, 2020 19:00
Well sorry to say but that didn't last long. Only a few hours later and I started getting the customary screen blackouts and dock disconnects once again. I suspect the DP MST bug may on the Linux (i915?) side, to do with Ice Lake machines.
Back to the `i915.enable_dp_mst=0` option for me, with one monitor connected via the TB daisy chain dock port.