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kernel 6.3-rc1 DisplayPort HDCP regression since commit 82986fd631fa04bcedaefe11a6b3767601cbe84f

Brief summary of the problem:

Since commit https://github.com/torvalds/linux/commit/82986fd631fa04bcedaefe11a6b3767601cbe84f the Linux 6.3-rc1 kernel has failed to boot on my system when using RX 580 GPU connected to a somewhat peculiar Dell display using DisplayPort. The same GPU and display do work when connected via HDMI.

Doing a git bisect arrived at the Linux kernel commit 82986fd631fa04bcedaefe11a6b3767601cbe84f as the first bad one but I did not attempt to revert it, so I can't 100% promise that it was successful.

Hardware description:

  • CPU:Intel i5-12400
  • GPU: 01:00.0 VGA compatible controller [0300]: Advanced Micro Devices, Inc. [AMD/ATI] Ellesmere [Radeon RX 470/480/570/570X/580/580X/590] [1002:67df] (rev e7)
  • System Memory: 32 GiB DDR5
  • Display(s): Dell U2414H
  • Type of Display Connection: DP

System information:

  • Distro name and Version: Gentoo ~amd64 with some custom ebuilds
  • Kernel version: Linux hostname 6.3.0-rc1 #1 SMP PREEMPT Mon Mar 6 10:57:14 EET 2023 x86_64 12th Gen Intel(R) Core(TM) i5-12400 GenuineIntel GNU/Linux
  • Custom kernel: Kernel from torvalds/linux
  • AMD official driver version: N/A

How to reproduce the issue:

For me just having the display connected via DP results in boot failure 100% of the time. Sometimes the keyboard caps lock key still functions, other times even that seems to not respond (but maybe I'm just not pressing it decisively enough?). The issue seems to happen as soon as amdgpu takes over the display from whichever driver had it previously.

Edited by Niklāvs Koļesņikovs