Public bug reported:
Hello,
I am experiencing a suspend/resume regression on a Lenovo ThinkPad X250 with
Intel Broadwell-U integrated graphics.
The problem occurs with Ubuntu 26.04 LTS kernel 7.0.0-28-generic and
kernel 7.0.0-29-generic. In kernel 7.0.0-27-generic process working
well.
Hardware:
* Lenovo ThinkPad X250
* Intel Broadwell-U GT2 / Intel HD Graphics 5500
* PCI ID: 8086:1616 (rev 09)
* Subsystem: Lenovo 17aa:2226
* Graphics driver: i915
Software:
* Ubuntu 26.04 LTS (Resolute Raccoon)
* Kernel: 7.0.0-29-generic
* x86_64
* PREEMPT_DYNAMIC
* /sys/power/mem_sleep: s2idle [deep]
Problem:
When the laptop is suspended by closing the lid, the system enters suspend
successfully. After opening the lid, the system resumes, but the internal
display does not come back. The graphical session/display remains unusable.
Switching to another virtual console with Ctrl+Alt+F3 also did not bring up a
usable console, so recovery through the GUI was not possible.
The suspend/resume sequence in the kernel log is:
PM: suspend entry (deep)
ACPI: PM: Preparing to enter system sleep state S3
ACPI: PM: Saving platform NVS memory
ACPI: PM: Low-level resume complete
ACPI: PM: Restoring platform NVS memory
ACPI: PM: Waking up from system sleep state S3
PM: suspend exit
However, immediately before entering S3 there are i915 warnings:
i915 0000:00:02.0: [drm] CPU PWM1 enabled
WARNING: drivers/gpu/drm/i915/display/intel_display_power.c:1225 at
assert_can_disable_lcpll+0x741/0x760 [i915]
The associated call trace includes:
assert_can_disable_lcpll
hsw_disable_lcpll.constprop.0
hsw_enable_pc8
intel_display_power_suspend_late
intel_uncore_suspend
i915_drm_suspend_late
i915_pm_suspend_late
pm_generic_suspend_late
pci_pm_suspend_late
A second warning occurs at the same point in the suspend sequence:
WARNING: drivers/gpu/drm/i915/display/intel_display_power.c:1232 at
assert_can_disable_lcpll+0x5e4/0x760 [i915]
After resume, the kernel also reports:
workqueue: i915_hpd_poll_init_work [i915] hogged CPU for >10000us 4
times, consider switching to WQ_UNBOUND
The display problem appears to be related to the i915 display power-
management path during suspend/resume.
There are also several ACPI _DSM evaluation failures during boot, but
the most relevant errors appear to be the i915 LCPLL/display power
warnings during suspend.
I have saved the complete kernel log from the affected boot as:
kernel-29-suspend.log
The relevant command used to collect it was:
sudo journalctl -b -k > ~/kernel-29-suspend.log
This appears to be a kernel regression affecting the Intel Broadwell
i915 driver and suspend/resume on this ThinkPad X250.
Expected behavior:
After opening the lid, the system should resume normally and the internal
display should become usable again.
Actual behavior:
The system reports a successful ACPI S3 resume, but the display does not return
and the graphical session cannot be used normally.
The issue is reproducible by booting kernel 7.0.0-29, suspending the
laptop by closing the lid, and opening the lid again.
** Affects: linux (Ubuntu)
Importance: Undecided
Status: New
** Attachment added: "kernel-29-suspend.log"
https://bugs.launchpad.net/bugs/2163112/+attachment/5990780/+files/kernel-29-suspend.log
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https://bugs.launchpad.net/bugs/2163112
Title:
i915 display fails to resume after suspend on ThinkPad X250 with
kernel 7.0.0-29
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