I seem to have very similar issues. Using a Lenovo ThinkPad X1 Carbon 7th gen and ThinkPad USB-C Dock Gen 2. But I also see this on a different docking station. I'm pretty sure they are both using USB-C DP- alt mode.
When I boot my laptop connected to the docking stations, I can see BIOS POST messages, but the moment it switches to my LUKS encryption prompt the display turns off. It is visible on the laptop screen. I don't think I see any relevant kernel messages in dmesg. This does not happen to me on 5.8.0-7642-generic (this is a Pop!OS specific kernel, but don't think that matters). I've also tested 5.11.0-25-generic, and the issues persists. This RedHat bug report seems very similar: https://bugzilla.redhat.com/show_bug.cgi?id=1879442 Which links to: https://gitlab.freedesktop.org/drm/intel/-/issues/2579 The DRM error "DPCD read on addr 0x60 for 1 bytes NAKed" was also reported there. And resolved with backports of the drm code to 5.11. Could this bug report be the same problem? ** Bug watch added: Red Hat Bugzilla #1879442 https://bugzilla.redhat.com/show_bug.cgi?id=1879442 ** Bug watch added: gitlab.freedesktop.org/drm/intel/-/issues #2579 https://gitlab.freedesktop.org/drm/intel/-/issues/2579 -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1908139 Title: ThinkPad T14s external display not working on ThinkPad USB-C Dock Gen2 Status in linux package in Ubuntu: Confirmed Bug description: laptop: ThinkPad T14s Gen 1 - AMD Ryzen 7 PRO 4750U docking station: ThinkPad USB-C Dock 2. Gen. external display: NE MultiSync EA275UHD OS: Ubuntu 20.10 - kernel 5.8.0 Plugging the external display into one of the docking station's two DisplayPort connectors leads to the screen resolution changing on the laptop's builtin display and the external display waking up but showing no picture and displaying "no-signal" after a bit. Plugging the external display into the docking station's HDMI connector leads to no visible reaction on either the external nor the builtin display. Plugging the external display into the laptop's builtin HDMI connector works as expected. The external display is recognized and shows an image. I have recorded the output on `dmesg` during the steps mentioned above and inserted explanations using `echo MSG >/dev/kmsg`. The output follows at the end of the message. I believe `ubuntu-bug` should also attach the full log. All above modes of connection work as expected with the same laptop, dock, and display on Windows 10 (installed as dual boot along side Ubuntu). All above modes of connection also work as expected with an older laptop (ThinkPad T470s - Ubuntu 20.04 - kernel 5.4.0), and the same dock and display. This leads me to believe that this is not a hardware issue. The following bug seems related, but seems to have been observed on faulty hardware according to its author. Therefore, I decided to open a separate bug report. https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1899336 ``` [ 343.372511] plugging DisplayPort into dock port 1 [ 352.666113] [drm] DP Alt mode state on HPD: 1 [ 352.749192] [drm] DM_MST: starting TM on aconnector: 000000002105a317 [id: 75] [ 352.858482] [drm] amdgpu_dm_irq_schedule_work FAILED src 9 [ 352.888400] [drm] amdgpu_dm_irq_schedule_work FAILED src 9 [ 352.892555] [drm] amdgpu_dm_irq_schedule_work FAILED src 9 [ 352.896719] [drm] amdgpu_dm_irq_schedule_work FAILED src 9 [ 352.900876] [drm] amdgpu_dm_irq_schedule_work FAILED src 9 [ 352.905596] [drm] amdgpu_dm_irq_schedule_work FAILED src 9 [ 352.910323] [drm] amdgpu_dm_irq_schedule_work FAILED src 9 [ 352.914485] [drm] amdgpu_dm_irq_schedule_work FAILED src 9 [ 377.353566] plugged in - no signal [ 396.728970] unplugging [ 403.001418] [drm] DM_MST: stopping TM on aconnector: 000000002105a317 [id: 75] [ 415.576397] unplugged [ 431.500729] plugging DisplayPort into dock port 2 [ 437.607724] [drm] DP Alt mode state on HPD: 1 [ 437.681116] [drm] DM_MST: starting TM on aconnector: 000000002105a317 [id: 75] [ 437.790303] [drm] amdgpu_dm_irq_schedule_work FAILED src 9 [ 437.820138] [drm] amdgpu_dm_irq_schedule_work FAILED src 9 [ 437.824305] [drm] amdgpu_dm_irq_schedule_work FAILED src 9 [ 437.828462] [drm] amdgpu_dm_irq_schedule_work FAILED src 9 [ 437.832619] [drm] amdgpu_dm_irq_schedule_work FAILED src 9 [ 437.837029] [drm] amdgpu_dm_irq_schedule_work FAILED src 9 [ 437.841984] [drm] amdgpu_dm_irq_schedule_work FAILED src 9 [ 437.846144] [drm] amdgpu_dm_irq_schedule_work FAILED src 9 [ 458.999849] plugged in - no signal [ 465.702949] unplugging [ 476.127418] [drm] DM_MST: stopping TM on aconnector: 000000002105a317 [id: 75] [ 476.956491] [drm] Failed to add display topology, DTM TA is not initialized. [ 488.792533] unplugged [ 529.801179] plugging HDMI into dock [ 536.721076] [drm] DP Alt mode state on HPD: 1 [ 536.792947] [drm] DM_MST: starting TM on aconnector: 000000002105a317 [id: 75] [ 536.901958] [drm] amdgpu_dm_irq_schedule_work FAILED src 9 [ 536.906123] [drm] amdgpu_dm_irq_schedule_work FAILED src 9 [ 536.910288] [drm] amdgpu_dm_irq_schedule_work FAILED src 9 [ 536.914611] [drm] amdgpu_dm_irq_schedule_work FAILED src 9 [ 536.919568] [drm] amdgpu_dm_irq_schedule_work FAILED src 9 [ 536.923725] [drm] amdgpu_dm_irq_schedule_work FAILED src 9 [ 536.927888] [drm] amdgpu_dm_irq_schedule_work FAILED src 9 [ 536.932047] [drm] amdgpu_dm_irq_schedule_work FAILED src 9 [ 536.936451] [drm] amdgpu_dm_irq_schedule_work FAILED src 9 [ 536.941486] [drm] amdgpu_dm_irq_schedule_work FAILED src 9 [ 536.945651] [drm] amdgpu_dm_irq_schedule_work FAILED src 9 [ 536.949808] [drm] amdgpu_dm_irq_schedule_work FAILED src 9 [ 537.010093] [drm:drm_dp_send_dpcd_read [drm_kms_helper]] *ERROR* mstb 00000000271ba325 port 1: DPCD read on addr 0x60 for 1 bytes NAKed [ 592.844147] plugged in - display does not react [ 597.998141] unplugging [ 604.657060] [drm] DM_MST: stopping TM on aconnector: 000000002105a317 [id: 75] [ 612.058516] unplugged [ 630.409181] plugging HDMI into laptop [ 637.125592] [drm] Failed to add display topology, DTM TA is not initialized. [ 639.077839] [drm] Failed to add display topology, DTM TA is not initialized. [ 639.192248] [drm] Failed to add display topology, DTM TA is not initialized. [ 683.221820] plugged in - working [ 690.347738] unplugging [ 694.212298] [drm] Failed to add display topology, DTM TA is not initialized. [ 725.466488] unplugged ``` ProblemType: Bug DistroRelease: Ubuntu 20.10 Package: linux-image-5.8.0-33-generic 5.8.0-33.36 ProcVersionSignature: Ubuntu 5.8.0-33.36-generic 5.8.17 Uname: Linux 5.8.0-33-generic x86_64 ApportVersion: 2.20.11-0ubuntu50.2 Architecture: amd64 AudioDevicesInUse: USER PID ACCESS COMMAND /dev/snd/controlC2: aj 1262 F.... pulseaudio /dev/snd/controlC1: aj 1262 F.... pulseaudio /dev/snd/controlC3: aj 1262 F.... pulseaudio /dev/snd/controlC0: aj 1262 F.... pulseaudio CasperMD5CheckResult: skip CurrentDesktop: ubuntu:GNOME Date: Mon Dec 14 22:11:01 2020 InstallationDate: Installed on 2020-12-12 (2 days ago) InstallationMedia: Ubuntu 20.10 "Groovy Gorilla" - Release amd64 (20201022) MachineType: LENOVO 20UHCTO1WW ProcFB: 0 amdgpudrmfb ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-5.8.0-33-generic root=/dev/mapper/vgubuntu-root ro quiet splash vt.handoff=7 RelatedPackageVersions: linux-restricted-modules-5.8.0-33-generic N/A linux-backports-modules-5.8.0-33-generic N/A linux-firmware 1.190.2 SourcePackage: linux UpgradeStatus: No upgrade log present (probably fresh install) dmi.bios.date: 09/15/2020 dmi.bios.release: 1.25 dmi.bios.vendor: LENOVO dmi.bios.version: R1CET56W(1.25 ) dmi.board.asset.tag: Not Available dmi.board.name: 20UHCTO1WW dmi.board.vendor: LENOVO dmi.board.version: Not Defined dmi.chassis.asset.tag: No Asset Information dmi.chassis.type: 10 dmi.chassis.vendor: LENOVO dmi.chassis.version: None dmi.ec.firmware.release: 1.25 dmi.modalias: dmi:bvnLENOVO:bvrR1CET56W(1.25):bd09/15/2020:br1.25:efr1.25:svnLENOVO:pn20UHCTO1WW:pvrThinkPadT14sGen1:rvnLENOVO:rn20UHCTO1WW:rvrNotDefined:cvnLENOVO:ct10:cvrNone: dmi.product.family: ThinkPad T14s Gen 1 dmi.product.name: 20UHCTO1WW dmi.product.sku: LENOVO_MT_20UH_BU_Think_FM_ThinkPad T14s Gen 1 dmi.product.version: ThinkPad T14s Gen 1 dmi.sys.vendor: LENOVO To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1908139/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
