Public bug reported:
TITLE:
i915: HDMI output hangs after DPMS off/on on Arrow Lake-P — "Failed to bring
PHY B to idle", PHY B 0c70 read/write failures, flip_done timeouts (regression
in 7.0, not seen on 6.17 OEM)
DESCRIPTION:
Summary
-------
On a Dell Pro Max 16 Premium (Arrow Lake-P iGPU), the display connected to the
built-in
HDMI port (HDMI-A-1, C10 PHY B) stops responding when the screen is turned off
and back on
by DPMS (screen blank while locked, then wake). The system keeps running but
the display
pipeline hangs: flip_done timeouts repeat every 10 s and the screen stays black
until reboot.
It has happened 3 times (Oct 26, 27, 29, 2026), with two different monitors
(Dell U2415 at
1920x1200@60, Dell P3421W at 3440x1440@60), always on HDMI-A-1. There was one
more
occurrence that recovered by itself (DDI BUF B timeout + FIFO underrun on
unlock).
USB-C/DP alt mode and Thunderbolt outputs on the same machine have not hit this.
All occurrences are on 7.0 kernels. No PHY errors in any boot on
6.11.0-1023-oem or
6.17.0-1033-oem (Oct 7–26). The first occurrence was on BIOS 1.9.0, before a
BIOS update to
1.13.1, so the BIOS update did not introduce it.
Caveat: the logs don't confirm the HDMI port was in use during the 6.x boots.
Hardware / software
-------------------
- Machine: Dell Pro Max 16 Premium MA16250 (SKU 0D33), BIOS 1.13.1 (also seen
on 1.9.0)
- iGPU: Intel Arrow Lake-P [8086:7d51] rev 03 (i915), DMC i915/mtl_dmc.bin
v2.21,
GuC 70.36.0 (kernel recommends 70.53.0)
- dGPU: NVIDIA [10de:2d39], open kernel module 615.71.09, PRIME on-demand
(HDMI-A-1 is wired to the Intel GPU)
- OS: Ubuntu 24.04, Xorg 21.1.12-1ubuntu1.9, GNOME/GDM
- Kernels affected: 7.0.0-38-generic (7.0.14). Now running 7.0.0-42-generic,
not yet reproduced there.
- Kernels apparently not affected: 6.11.0-1023-oem, 6.17.0-1033-oem
Steps to reproduce
------------------
1. Connect a monitor to the built-in HDMI port (Xorg session).
2. Lock the screen and let it blank (DPMS off), e.g. 10 minutes idle.
3. Wake it (move the mouse, or unlock).
4. Intermittently (3 hangs over 4 days of normal use), the display does not
come back.
Error pattern (identical each time)
-----------------------------------
i915 0000:00:02.0: [drm] *ERROR* Failed to bring PHY B to idle.
i915 0000:00:02.0: [drm] *ERROR* PHY B Read 0c70 failed after 3 retries.
i915 0000:00:02.0: [drm] *ERROR* PHY B Write 0c70 failed after 3 retries.
i915 0000:00:02.0: [drm] *ERROR* Timeout waiting for DDI BUF B to get active
i915 0000:00:02.0: [drm] *ERROR* [CRTC:268:pipe B] flip_done timed out
i915 0000:00:02.0: [drm] pipe state doesn't match!
... mismatch in dpll_hw_state
expected: cx0pll_hw_state: lane_count: 4, use_c10: yes, tbt_mode: no;
c10pll clock: 479625, fracen: yes
found: cx0pll_hw_state: lane_count: 4, use_c10: yes, tbt_mode: no;
c10pll clock: 61440, fracen: no
WARNING: ... intel_modeset_verify.c:225 at verify_crtc_state ... Xorg
[CONNECTOR:516:HDMI-A-1] commit wait timed out
The PLL always reads back 61440 kHz / fracen=no (also on the earlier
occurrence, where
154000 kHz was expected), which suggests the C10 PHY never accepted programming
after the
power transition (unresponsive message bus), while the driver carries on as if
the PLL were
enabled. The earlier occurrence also had a WARNING trace:
Xorg → drm_connector_property_set_ioctl → drm_atomic_connector_commit_dpms →
intel_post_plane_update → hsw_audio_codec_enable →
intel_crtc_wait_for_next_vblank.
Separately, with a Thunderbolt/USB4 dock (no HDMI), there are many
"DPLL 1: pll hw state mismatch" WARNINGs (verify_single_dpll_state,
intel_dpll_mgr.c:4945)
without a hang.
Possibly related
----------------
- Arch Linux forum, same PHY 0c70 errors on Meteor Lake after s2idle resume,
regression on
7.0, fine on 6.19: https://bbs.archlinux.org/viewtopic.php?id=313469
- dri-devel, "fix PLL enable failure handling on Meteor Lake" (May 2026):
https://mid.mail-archive.com/[email protected]/msg605529.html
Attached: kernel log excerpts for all occurrences (hostname redacted).
I can retest on 6.17 OEM / 7.0.0-42, with drm.debug=0xe, or with
i915.enable_dc=0 if useful.
ProblemType: Bug
DistroRelease: Ubuntu 24.04
Package: linux-image-7.0.0-42-generic 7.0.0-42.42~24.04.1
ProcVersionSignature: Ubuntu 7.0.0-42.42~24.04.1-generic 7.0.14
Uname: Linux 7.0.0-42-generic x86_64
ApportVersion: 2.28.3-0ubuntu0.1
Architecture: amd64
AudioDevicesInUse:
USER PID ACCESS COMMAND
/dev/snd/controlC1: paul.weidinger 4158 F.... pipewire
paul.weidinger 4162 F.... wireplumber
/dev/snd/controlC0: paul.weidinger 4162 F.... wireplumber
/dev/snd/seq: paul.weidinger 4158 F.... pipewire
CRDA: N/A
CasperMD5CheckResult: unknown
CurrentDesktop: ubuntu:GNOME
Date: Thu Oct 29 16:28:48 2026
DistributionChannelDescriptor:
# This is the distribution channel descriptor for Ubuntu 24.04 for Dell
# For more information see http://wiki.ubuntu.com/DistributionChannelDescriptor
canonical-oem-somerville-noble-oem-24.04b-proposed-20250521-513
IwConfig:
lo no wireless extensions.
wlp0s20f3 no wireless extensions.
docker0 no wireless extensions.
MachineType: Dell Inc. Dell Pro Max 16 Premium MA16250
ProcEnviron:
LANG=en_US.UTF-8
PATH=(custom, no user)
SHELL=/bin/bash
TERM=alacritty
XDG_RUNTIME_DIR=<set>
ProcFB: 0 i915drmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-7.0.0-42-generic
root=UUID=80f817ed-fac2-4ce3-a0eb-0d3206518127 ro quiet splash vt.handoff=7
RelatedPackageVersions:
linux-restricted-modules-7.0.0-42-generic N/A
linux-backports-modules-7.0.0-42-generic N/A
linux-firmware 20240318.git3b128b60.0ubuntu3.1
SourcePackage: linux-hwe-7.0
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 08/03/2026
dmi.bios.release: 1.13
dmi.bios.vendor: Dell Inc.
dmi.bios.version: 1.13.1
dmi.board.name: 02D0TH
dmi.board.vendor: Dell Inc.
dmi.board.version: A04
dmi.chassis.type: 10
dmi.chassis.vendor: Dell Inc.
dmi.ec.firmware.release: 1.18
dmi.modalias:
dmi:bvnDellInc.:bvr1.13.1:bd08/03/2026:br1.13:efr1.18:svnDellInc.:pnDellProMax16PremiumMA16250:pvr:rvnDellInc.:rn02D0TH:rvrA04:cvnDellInc.:ct10:cvr:sku0D33:pfaDellProMaxLaptops:
dmi.product.family: Dell Pro Max Laptops
dmi.product.name: Dell Pro Max 16 Premium MA16250
dmi.product.sku: 0D33
dmi.sys.vendor: Dell Inc.
** Affects: linux-hwe-7.0 (Ubuntu)
Importance: Undecided
Status: New
** Tags: amd64 apport-bug noble wayland-session
** Attachment added: "i915-phy-b-freeze-logs.txt"
https://bugs.launchpad.net/bugs/2172545/+attachment/6013486/+files/i915-phy-b-freeze-logs.txt
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https://bugs.launchpad.net/bugs/2172545
Title:
i915: HDMI display hangs after screen blank/wake on Arrow Lake-P -
"Failed to bring PHY B to idle" (regression in 7.0 kernel)
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