Public bug reported:
Bug 1 - i915 HPD workqueue hard lockup (primary issue)
With an HDMI monitor connected, the system hard locks at idle within
minutes of booting. The kernel does not panic or produce an oops, it
freezes completely with no further log output. kdump does not capture a
vmcore, consistent with a hard CPU lockup occurring too fast for the
crash kernel to initialise.
The following warning appears repeatedly in the journal before the
crash:
workqueue: i915_hpd_poll_init_work [i915] hogged CPU for >10000us 4 times,
consider switching to WQ_UNBOUND
workqueue: i915_hpd_poll_init_work [i915] hogged CPU for >10000us 5 times,
consider switching to WQ_UNBOUND
Shortly before the crash:
gnome-shell: Cursor update failed: drmModeAtomicCommit: Invalid argument
Physically unplugging the HDMI cable also triggers an immediate hard
crash, indicating the bug is in the interrupt-driven HPD path as well as
the polling loop.
Note: modinfo i915 | grep hpd returns no results on this kernel build,
there are no HPD-specific i915 module parameters exposed.
Workaround for Bug 1:
Adding the following kernel parameters resolves the lockup:
drm_kms_helper.poll=0 i915.enable_psr=0 i915.enable_dc=0
Bug 2 - SOF audio IPC storm on HDMI PCM streams (secondary issue)
On the default kernel configuration, the SOF audio driver generates a
continuous storm of IPC errors at boot targeting HDMI2 and HDMI3 PCM
streams:
sof-audio-pci-intel-cnl 0000:00:1f.3: NHLT table not found
sof-audio-pci-intel-cnl 0000:00:1f.3: ipc tx error for 0x60010000 (msg/reply
size: 108/20): -5
sof-audio-pci-intel-cnl 0000:00:1f.3: sof_ipc3_pcm_hw_params: pcm3 (HDMI2), dir
0: STREAM_PCM_PARAMS ipc failed for stream_tag 1
HDMI2: ASoC error (-5): at dpcm_fe_dai_hw_params() on HDMI2
The error repeats hundreds of times per boot. The missing NHLT ACPI
table means the SOF driver cannot configure the HDMI audio streams.
alsactl restore also fails with exit code 99 as a downstream
consequence.
Workaround for Bug 2:
snd_intel_dspcfg.dsp_driver=1
This forces the legacy snd_hda_intel driver instead of SOF, which
initialises cleanly on this hardware.
Full workaround - current working kernel parameters:
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash snd_intel_dspcfg.dsp_driver=1
drm_kms_helper.poll=0 i915.enable_psr=0 i915.enable_dc=0"
Steps to reproduce Bug 1:
1. Boot Ubuntu 24.04.4 with kernel 6.17.0-20-generic on a Google Chromebox
Ambassador
2. Connect a monitor via HDMI
3. Leave the system idle for 2-5 minutes
4. System hard locks with no kernel panic or oops captured
Steps to reproduce Bug 2:
1. Boot Ubuntu 24.04.4 with kernel 6.17.0-20-generic on a Google Chromebox
Ambassador
2. Check journal: journalctl -b | grep sof-audio
3. Hundreds of IPC error messages visible from boot
quokka@quokka-Ambassador:~$
ProblemType: Bug
DistroRelease: Ubuntu 24.04
Package: linux-image-6.17.0-20-generic 6.17.0-20.20~24.04.1
ProcVersionSignature: Ubuntu 6.17.0-20.20~24.04.1-generic 6.17.13
Uname: Linux 6.17.0-20-generic x86_64
ApportVersion: 2.28.1-0ubuntu3.8
Architecture: amd64
AudioDevicesInUse:
USER PID ACCESS COMMAND
/dev/snd/controlC0: quokka 2060 F.... wireplumber
/dev/snd/seq: quokka 2054 F.... pipewire
CRDA: N/A
CasperMD5CheckResult: pass
CurrentDesktop: ubuntu:GNOME
Date: Wed Apr 8 21:53:26 2026
InstallationDate: Installed on 2026-04-08 (0 days ago)
InstallationMedia: Ubuntu 24.04.4 LTS "Noble Numbat" - Release amd64 (20260210)
Lsusb:
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 001 Device 002: ID 046d:c52b Logitech, Inc. Unifying Receiver
Bus 001 Device 003: ID 8087:0026 Intel Corp. AX201 Bluetooth
Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
MachineType: Google Ambassador
ProcEnviron:
LANG=en_US.UTF-8
PATH=(custom, no user)
SHELL=/bin/bash
TERM=xterm-256color
XDG_RUNTIME_DIR=<set>
ProcFB: 0 i915drmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-6.17.0-20-generic
root=UUID=edf1cdf1-f7a0-4bee-bd50-b4b07ac8c5b5 ro quiet splash
snd_intel_dspcfg.dsp_driver=1 drm_kms_helper.poll=0 i915.enable_psr=0
i915.enable_dc=0
crashkernel=2G-4G:320M,4G-32G:512M,32G-64G:1024M,64G-128G:2048M,128G-:4096M
vt.handoff=7
RelatedPackageVersions:
linux-restricted-modules-6.17.0-20-generic N/A
linux-backports-modules-6.17.0-20-generic N/A
linux-firmware 20240318.git3b128b60-0ubuntu2.25
SourcePackage: linux-hwe-6.17
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 01/25/2026
dmi.bios.release: 0.0
dmi.bios.vendor: coreboot
dmi.bios.version: MrChromebox-2512.2
dmi.board.name: Ambassador
dmi.board.vendor: Google
dmi.board.version: rev4
dmi.chassis.type: 35
dmi.chassis.vendor: Google
dmi.ec.firmware.release: 0.0
dmi.modalias:
dmi:bvncoreboot:bvrMrChromebox-2512.2:bd01/25/2026:br0.0:efr0.0:svnGoogle:pnAmbassador:pvrrev4:rvnGoogle:rnAmbassador:rvrrev4:cvnGoogle:ct35:cvr:skusku33554437:
dmi.product.family: Google_Puff
dmi.product.name: Ambassador
dmi.product.sku: sku33554437
dmi.product.version: rev4
dmi.sys.vendor: Google
** Affects: linux-hwe-6.17 (Ubuntu)
Importance: Undecided
Status: New
** Tags: amd64 apport-bug noble wayland-session
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https://bugs.launchpad.net/bugs/2147571
Title:
i915 HPD workqueue hard lockup and SOF audio IPC storm on Google
Chromebox Ambassador with kernel 6.17.0-20-generic
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