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U4021QW, M2T102 update, TB3/DP 1.4 issue
- So this is an FYI, but also a PSA for a potential fix.
I had my U4021QW replaced initially because of this, but the next one did the same after the update.
I have the Dell XPS 13 7390 2-in-1. This is a TB3/DisplayPort 1.4 laptop. It has no issue doing the full 5120x2160 60Hz, via the TB3 port on the U4021QW.
I also have a Desktop with a GTX 1050 Ti. This has the latest DP 1.4 firmware update and has no issues with the 60Hz as well.
On the initial firmware M2T101, both computers worked without issues by themselves. However, once the Desktop would go into 'display sleep' mode, if I switched to the Desktop, the U4021QW wouldn't detect any signal and would not give power to the USB ports for me to wake it up. One of the fixes to the firmware M2T102 is supposed to fix this.
I installed the M2T102 while connected to my XPS 13 7390 2-in-1. When completed, IMMEDIATELY, the U4021QW kept going on and off, detecting and undetecting the laptop. It wasn't until I did a full restart of the computer did it work, but the moment I unplugged and replugged back in later, same issue with the laptop. The laptop continued to work fine with a different TB3 TB16 dock, it was specific to this U4021QW. My wife's XPS 13 9380 (DP 1.2) also had no issue after the firmware update.
Nothing worked. Dell eventually replaced the U4021QW. I received it with the original firmware but it still had that same KVM issue so I ultimately decided to try the firmware again. Sadly, it instantly caused the issue again. Very specific to my XPS 7390 2in1. But here's where it get's interesting.
I found two ways to fix this =
One: you can disable the Thunderbolt technology entirely on the laptop - then there is no issue. That isn't great for me though, since I also use the TB16 dock at work (without this monitor) so I need TB activated. The working fix: if when selecting the Thunderbolt input on the monitor, if you hold the physical button while selecting it for 8 seconds, you can force the Monitor to go into DP 1.2 mode. Oddly, this fixes the issue AND still shows the full 5120x2160@60hz.
All to say, why would this new firmware mess with the TB3 and DP 1.4 aspect? It seems to be the combination of those 2 that the firmware messed with. On the bright side, the input switching to DP 1.2 somehow fixes it without losing any features. This firmware update does also solve the KVM issue I described, which I am super thankful for!
Just wanted to see if anyone had any insight....or if anything, has a possible solution.
FlyingGanz
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December 6th, 2021 00:00
Thanks for sharing your useful workaround @Chris1642. It saved me from returning my monitor. I too have the same combination as you, i.e. 7390 2-in-1 with a U4021QW. After installing the M2T102 update on 5 Dec, my monitor stopped working as well with TB3/DP 1.4 mode. @DELL-Cares Any updates? It has been a month since the last response.
Chris1642
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December 11th, 2021 18:00
@DELL-Cares Wanted to check in and see if there have been any updates to this? The workaround is still working....but by default, without switching to DP 1.2, it cripples the TB3 port.
FlyingGanz
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March 8th, 2022 01:00
I just tried the M2T104 firmware update. Still the same issues! @DELL-Cares, can you get the Display Team to look into this issue? This is not how this monitor is supposed to work.
DELL-Chris M
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March 9th, 2022 10:00
The XPS 13 7390 2-in-1 drivers page released BIOS 1.14.0 yesterday March 8, 2022. Please install it and retest.
The XPS 13 9380 drivers page released BIOS 1.17.0 on January 13, 2022. If you have not done so, install it and retest.
Laptop BIOS installation instructions
* Connect the external power adapter to the Laptop
* The Laptop is not connected to any dock, external monitor, hard drive, printer, etc.
* Download/Save the latest BIOS file to the Windows desktop
* Close/end task all unnecessary software applications (Browsers, Dell SupportAssist, Dell Update Application, Dell Display Manager, Steam, Anti-virus, etc.)
* Find the saved BIOS file on the Windows desktop
* Right click the file and choose, "Run as administrator". Note, you do not need to "extract" the file. Just run it
* Follow the prompted instructions. The Laptop will reboot on its own, do not force it
lkraav
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May 6th, 2024 13:17
Happy 2024, y'all.
I'm on 7390 2-in-1 BIOS 1.30.0 (latest), and U4021QW firmware M2T105 (latest), and this problem still exists exactly as described in convo opener. OS is Linux, with a large variety of kernels tested: latest 6.6, now 6.8, behavior is exactly the same so I don't think it's a computer software issue.
Disabling Thunderbolt in BIOS makes the monitor work instantly.
I have not yet tested the 8-sec monitor input selection button trick for DP 1.4 -> 1.2 downgrade, this was news to me from this thread. Will follow up with results on that.
EDIT AMAZING DP 1.2 made Thunderbolt connection work instantly. Wow, had been running on a sub-optimal headachy ("why doesn't this thing connect properly") configuration for a few years, what a waste!
(edited)