[SOLVED] kernel 5.16: USB-C 3.1 DisplayPort Adapter no longer working

mephinet · 2022-01-23 20:01:49

Dear fellow arch users,

I recently bought an i-tec USB-C 3.1 Dual 4K DP Video Adapter for my Lenovo ThinkPad L14 Gen 2 with Intel TigerLake-LP GT2 (Iris Xe). No nvidia involved (I've learned from my mistakes...). I'm using it to connect my two NEC MultiSync EA224Wmi LCD displays with a resolution of 1920x1080 using (I assume) the DisplayPort alternate mode.

Since upgrading to the Linux kernel to version 5.16.[0/1/2], the video adapter no longer works: the external screens remain blank, and are no longer shown as "connected" on the xrandr output. Downgrading to kernel 5.15.13 (without any other changes to the system) gets the video adapter back working.

Running through the kernel logs and the modules loaded, this is what I found out so far: With 5.16 the mei_pxp (Protected Xe Path) module has landed. This results in the following changes:

typec_displayport module is no longer loaded by modprobe
"ACPI: bus type drm_connector registered" now, instead of type PCI back in 5.15.13
with 5.15.13: ucsi_acpi USBC000:00: UCSI_GET_PDOS returned 0 bytes. Now with 5.16: ucsi_acpi USBC000:00: PPM init failed (-110)
Xorg.0.log does not show any error messages, but never mentions the outputs DP-2-*

Blacklisting mei_pxp does not magically solve the issue.

I posted the kernel logs here: https://gist.github.com/mephinet/c38d2e … 046865cd4f

Any hint how to get USB-C DisplayPort alternate mode back working, or where to file the bug report?
Thanks!

Last edited by mephinet (2022-03-05 12:08:29)

seth · 2022-01-23 20:31:26

The dmesg is from "Linux version 5.15.13-arch1-1", use "sudo journalctl -b -1" to access the system journal from the prev boot (or increase the offset accordingly) - the 5.16 logs are probably far more insteresting.

mephinet · 2022-01-23 20:58:42

Thanks for checking the gist, seth. The log of the kernel 5.16.1 can be found further down the page: https://gist.github.com/mephinet/c38d2e … rch1-1-txt . Unfortunately, github doesn't give you any visual clue that there will be files further down the road...

mephinet · 2022-01-25 22:28:36

I did some further experiments, now I conform that the same issue happens when using xf86-video-intel instead of modesetting.
I compared the /sys/bus/pci/drivers/i915/0000:00:02.0/drm/card0/ directory: While under 5.15.13 it contained subdirectories for card0-DP-1 to card0-DP-6, with 5.16.2, it only contains card0-DP-1 to card0-DP-4 - so this is another indication that it's caused by the i915 driver in the kernel.
Do you recommend reporting the issue upstream?

seth · 2022-01-25 22:36:36

Sorry, yes - the only thing that's obvious in the dmesg is PXP, there're no link training issues or so.
Do you get an output when booting "nomodeset" (you won't get a working displayserver, but the multi-user.target on a lousy resolution should™ work fine)

mephinet · 2022-02-21 21:13:30

A short update to this issue: Intel has developed a bugfix that solves the issue on my device. It has been pushed to intel-gfx and should find its way into the kernel sooner or later...

mephinet · 2022-03-05 12:06:45

The bugfix has now landed in the stable Arch kernel: with 5.16.12-arch1-1, the DisplayPort adapter works again!

Arch Linux

#1 2022-01-23 20:01:49

[SOLVED] kernel 5.16: USB-C 3.1 DisplayPort Adapter no longer working

#2 2022-01-23 20:31:26

Re: [SOLVED] kernel 5.16: USB-C 3.1 DisplayPort Adapter no longer working

#3 2022-01-23 20:58:42

Re: [SOLVED] kernel 5.16: USB-C 3.1 DisplayPort Adapter no longer working

#4 2022-01-25 22:28:36

Re: [SOLVED] kernel 5.16: USB-C 3.1 DisplayPort Adapter no longer working

#5 2022-01-25 22:36:36

Re: [SOLVED] kernel 5.16: USB-C 3.1 DisplayPort Adapter no longer working

#6 2022-02-21 21:13:30

Re: [SOLVED] kernel 5.16: USB-C 3.1 DisplayPort Adapter no longer working

#7 2022-03-05 12:06:45

Re: [SOLVED] kernel 5.16: USB-C 3.1 DisplayPort Adapter no longer working

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