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Mikhail G avatar Ubuntu

DP alt mod display stopped working

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Mikhail G

After about 6 months external dell 4k display stopped working with laptop (ubuntu 20.04) via USB type C.

Since February 2022 I have setup: Dell Lalilude 7410 with Ubuntu 20.04, with 5.13.0-35 kernel and Dell S2722QC display. It worked fine: power supply, video and keyboard with mouse via single type-c cable

A week ago it stopped working (I didn't update anything).

  • Laptop now see only display usb hub (keyboard and mouse)
  • Display don't appear in lshw
  • Display works with two another laptops with win10 -- so I assume that display and cable are working
  • Laptop works with two another usb-c display FullHD and 4K Lenovo (not simultaneously, checked in office) -- so I assume that laptop port is working
  • If I connect display to small hub via hdmi, and then connect it to laptop via USB-C, display works -- so I assume that 'video' part of laptop port is working?

After the problem appeared I decided to make apt update && apt upgrade and also fwupdmgr get-updates There is no more updates:

 • PC611 NVMe SK hynix 512GB
 • Thunderbolt host controller
 • UEFI Device Firmware
 • UEFI Device Firmware
Devices with the latest available firmware version:
 • System Firmware
 • UEFI dbx
No updates available for remaining devices

In lsmod I see typec_displayport.

I didn't change anything in UEFI before. I tried to turn Thunderbolt off, reboot and turn it on, didn't help.

Tried to reset to defaults display settings, didn't help. Also I checked that there is no community available firmware for this display. Current display firmware M3B101

There are a lot of questions on topic that USB-C displays don't work with Ubuntu, mine worked, but somehow stopped. Can you please help how to return USB-C connection?

UPD: I tried to boot with older kernels (5.4, 5.11, 5.13).

Looks like apt update/upgrade or 5.15 broke usb typec, because display stopped working with typec hub, only direct hdmi.

I updated to 22.04 and kernel 5.19 -- it fixed working with HDMI->docking station->typec laptop, but no luck with typec from display to laptop directly

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guiverc avatar
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guiverc
You mention the 5.13 kernel, which went [EOL some time ago](https://fridge.ubuntu.com/2022/07/19/ubuntu-21-10-impish-indri-end-of-life-reached-on-july-14-2022/) meaning Ubuntu 20.04 LTS using the HWE kernel stack upgraded to 5.15. You should upgrade your system, though if it was that upgrade (*kernel change from 5.13 to 5.15 was long ago now*) that is useful detail and switching to the GA kernel stack maybe an easy fix, but why mention details that are month(s) out of date? Did this problem just appear, in which case what change was made recently & why the EOL kernel?
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Mikhail G avatar
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Mikhail G
I upgraded to 5.15 only yesterday trying to fix the problem. It worked with old kernel fine. Also I found that hdmi->dock->usb-c dont work anymore. And there in no `typec_displayport` in lsmod after reboot. modprobe didnt help
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guiverc avatar
cn flag
guiverc
I'd likely boot *live* 20.04 LTS media using the GA kernel stack (ie. 5.4 kernel as that is supported for the life of the product being the most *stable*, see https://wiki.ubuntu.com/Kernel/LTSEnablementStack for info on kernel stack choices; GA, HWE or for some OEM) and see how that performs, does all hardware work as expected. If you've no closed-source kernel modules (*3rd party video modules/drivers for example*) multiple kernel stacks can co-exist on the same install, however some 3rd party modules prevent that. If 5.4 looks good *live*, I'd add the GA kernel stack to your box & try it...
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guiverc avatar
cn flag
guiverc
You can remove the HWE kernel stack later, or leave both installed & select at boot which you'll use (*side effect is only slightly more disk space needed, plus slightly larger upgrades as both kernel stacks will get upgrades*). An alternative also open is to wait for other users of this site, who may have more knowledge with your hardware/issue than I do, and provide alternate options. My 2c. (*I'm thinking kernel stack as you mentioned 5.13 & 5.15 which implies kernel change is cause, so why not use older supported kernel stack? 5.13 is unsafe online, 5.4 is safe*)
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Mikhail G avatar
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Mikhail G
I tried ubuntu 20.04 live usb, display didnt work I already tried 5.11 and 5.13, didnt work. I have 5.4.0 installed, will try to boot with it
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Mikhail G avatar
va flag
Mikhail G
boot on 5.4.0-126-generic, didnt work
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Mikhail G avatar Ubuntu
va flag
Mikhail G

After all updates and upgrades the solution was to use compressed air on laptop port and cable connector. I didn't see any debris or something else, but it helped

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