Multimonitor support broken on kernel 6.5.0-1024.25_oem on Lenovo Thunderbolt 3 Gen 2 USB-C dock

[Austin Esquirell]

Updating to 6.5.0-1024.25_oem from 6.5.0-1023.24_oem breaks HDMI video on the Lenovo Thunderbolt 3 Gen 2 USB-C dock. I am using a Thinkpad P16s with a Ryzen 7 PRO 7840U CPU and Ubuntu 22.04.4 LTS.

When using this new kernel version, all monitors plugged in via the dock display nothing during boot and after logging in to Ubutnu. The monitors are also not detected in the Settings->Displays section. I am using 2 HDMI Dell monitors in addition to the built-in display on the Laptop. The monitors show that they do not detect any input (as opposed to receiving a blank/black input).

Manually booting to the old 6.5.0-1023.24_oem kernel in GRUB fixes the issue.

It looks like there was a fix for HDMI/DP audio using USB-C docks in the new 6.5.0-1024.25_oem kernel; Maybe the issue is there.

This was the changelog entry:

* Fix inaudible HDMI/DP audio on USB-C MST dock (LP: #2064689)
    - SAUCE: drm/i915/audio: Fix audio time stamp programming for DP

And here is a link to that issue: https://launchpad.net/bugs/2064689

If there are any logs or additional details I can provide, I am happy to help.

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Martin Nyström (manys05)]

I can confirm this issue affects users of HP docks as well. We have two users with Lenovo P16v & P14s that use HP Thunderbolt Dock 230W G2.

After booting to 1023-oem it works again.

[Leopoldo Pena (leopenausa)]

Bug confirmed on a Lenovo Thunderbolt 4 workstation dock with two external monitors (hdmi and displayport) running a Lenovo Thinkpad Z16 Gen2 with AMD GPU and Ubuntu 22.04.4 LTS.

Confirm that rolling back from 6.5.0-1024.25_oem to 6.5.0-1023.24_oem fixes this issue.

[Norbert Schultz (zaiib)]

Confirming on Thinkpad Z13 and Dell WD19TB Dock. 1023 seems to fix this issue.

[Kai-Heng Feng (kaihengfeng)]

6.5 OEM kernel will be retired soon. Can you please enable -proposed pocket and install linux-generic-hwe-22.04-edge to see if the issue is resolved on 6.8 kernel?

[Austin Esquirell (ajesquirell)]

The 6.8.0-38-generic kernel seems to work correctly with my Lenovo Thunderbolt 3 Gen 2 USB-C dock (but I have not tested other features or stability).

Will a 6.8 oem kernel will be released that users can automatically update to? If so, perhaps the solution could be to just upgrade to 6.8. But for the time being the broken 6.5 kernel is confusing for people who have Ubuntu preinstalled from the factory with the oem kernel as it will appear to be broken out of the box. But maybe there is something else I am not understanding about the kernel workflow. Could you shed some light on this?

Thanks!

[Leopoldo Pena (leopenausa)]

Anyone has tested if latest 6.5.0-1024.26_oem update fixed this issue? I am in production machine and can't test right now.
thanks

[Austin Esquirell (ajesquirell)]

I think you mean 1025.26, and yes, it is still broken in that release.

My team has also experienced other monitor related issues on the 6.8.0-38-generic kernel, so we are still hoping for a fix on 6.5 oem. We are using 6.5.0-1023 for the time being.

[Mario Limonciello (superm1)]

Canonical 6.5 series seems to have picked up at least one bad commit that was reverted upstream.

commit 15c983d0cbb5a158eafb9cb88e6d8dfc4477d9c2
Author: Melissa Wen <email address hidden>
Date: Fri Dec 29 15:25:00 2023 -0100

    drm/amd/display: fix bandwidth validation failure on DCN 2.1

    BugLink: https://bugs.launchpad.net/bugs/2059068

    commit 3a0fa3bc245ef92838a8296e0055569b8dff94c4 upstream.

    IGT `amdgpu/amd_color/crtc-lut-accuracy` fails right at the beginning of
    the test execution, during atomic check, because DC rejects the
    bandwidth state for a fb sizing 64x64. The test was previously working
    with the deprecated dc_commit_state(). Now using
    dc_validate_with_context() approach, the atomic check needs to perform a
    full state validation. Therefore, set fast_validation to false in the
    dc_validate_global_state call for atomic check.

    Cc: <email address hidden>
    Fixes: b8272241ff9d ("drm/amd/display: Drop dc_commit_state in favor of dc_commit_streams")
    Signed-off-by: Melissa Wen <email address hidden>
    Signed-off-by: Hamza Mahfooz <email address hidden>
    Signed-off-by: Alex Deucher <email address hidden>
    Signed-off-by: Greg Kroah-Hartman <email address hidden>
    Signed-off-by: Portia Stephens <email address hidden>
    Signed-off-by: Stefan Bader <email address hidden>

Mainline revert:
https://git.kernel.org/torvalds/c/c2ab9ce0ee7225fc05f58a6671c43b8a3684f530
Stable revert:
https://git.kernel.org/stable/c/6266b3a312b7f69c883c2d7c82d85772464421d2