Public bug reported:
On a ThinkPad T480 (Intel UHD 620, Kaby Lake-R) running Kubuntu 26.04
with Plasma 6 Wayland, resuming from suspend frequently leaves the
internal panel (eDP-1) black. KWin loses access to the DRM device and
its atomic modeset test fails with EINVAL.
This is NOT a new failure in 7.0.0-27/-28 — it is present as far back as
7.0.0-15 — but its frequency increased roughly 12x between 7.0.0-22 and
7.0.0-27/-28, which is what turned it from a rare annoyance into a daily
blocker.
ERROR SIGNATURE
Logged by the compositor at the moment of resume:
kwin_wayland_drm: Atomic modeset test failed! Invalid argument
kwin_wayland_drm: Failed to open drm device
("Invalid argument" = EINVAL; some occurrences report "No such file or
directory" = ENOENT.)
The kernel itself logs no error at that moment. The i915 messages
present in dmesg (*ERROR* Atomic update failure on pipe A ... scanline
start 1066) are vblank-timing warnings that also occur when everything
works, and appear unrelated.
MEASURED FREQUENCY BY KERNEL
Counted across this machine's full journal history (Nov 2025 - Jul
2026), same hardware, same monitor layout, same Plasma version:
kernel resumes modeset failed per resume drm open failed per resume
7.0.0-22 60 51 0.85 24 0.40
7.0.0-27 5 25 5.0 5 1.00
7.0.0-28 22 237 10.8 30 1.36
A clean boot on 7.0.0-22 taken after the regression appeared showed 0
"Failed to open drm device" across 2 resumes with the internal panel
working, while a comparable 7.0.0-28 boot showed 9.
Failures also occur at session start (sddm-helper-start-wayland), not
only on resume, so a suspend cycle is not strictly required to trigger
it.
IMPACT
Internal panel stays black after resume; the session behaves as if an
external monitor were attached. Recovery requires restarting the
compositor from a TTY (systemctl --user restart plasma-
kwin_wayland.service), which loses unsaved work, or a hard power cycle.
Workaround in use: boot 7.0.0-22, which reduces the frequency enough to
be usable, at the cost of missing later kernel security updates.
RULED OUT
- mesa: libgbm1 moved 25.2.8 -> 26.0.3 on the same day the errors first appear
(2026-05-18, the 26.04 release upgrade). Tested by forcing KWin to stop using
GBM buffer modifiers (KWIN_DRM_USE_MODIFIERS=0): the failure rate got WORSE
(21.5 modeset failures per resume). Not mesa.
- KDE/KWin version: unchanged across the -22 vs -28 comparison above
(kwin-wayland 4:6.6.5-0ubuntu0.1 in both cases).
- i915 PSR: disabling Panel Self Refresh (i915.enable_psr=0, verified on the
kernel cmdline) changed nothing.
- Compositor-level recovery: calling kscreen-doctor on resume cannot help,
since KWin has already lost the DRM device.
POSSIBLY RELATED
- KDE Bug 520008 - same symptom and log signature on Ubuntu 26.04 + i915 +
external monitor + Plasma 6.6: https://bugs.kde.org/show_bug.cgi?id=520008
- Independent report of suspend/resume breakage on Intel + Ubuntu 26.04 fixed
by reverting 7.0.0-27 -> 7.0.0-22:
https://community.frame.work/t/ubuntu-26-04-suspend-resume-crash-on-kernel-7-0-0-27/83394
STEPS TO REPRODUCE
1. ThinkPad T480, Kubuntu 26.04, Plasma 6 Wayland session.
2. Connect a DisplayPort MST dock with an external monitor (3840x2160@60 on
DP-1; a second monitor is enumerated on DP-4 but left disabled).
3. Suspend (lid close or systemctl suspend), wait, resume with the lid open.
4. Repeat over several cycles - the failure is intermittent, so a single cycle
may succeed. On 7.0.0-28 it occurs within a handful of resumes; on 7.0.0-22 it
takes considerably longer to reproduce.
EXPECTED: Internal panel is re-enabled on resume; KWin's atomic modeset
succeeds.
ACTUAL: Internal panel stays black; KWin logs repeated "Atomic modeset
test failed! Invalid argument" and "Failed to open drm device".
SYSTEM
- ThinkPad T480 (20L6S0CE41), BIOS N24ET81W (1.56), 2025-09-06
- Intel Core i5-8350U
- Intel UHD Graphics 620, Kaby Lake-R GT2 [8086:5917] rev 07, driver i915
- Kubuntu 26.04 LTS, KDE Plasma 6, Wayland, systemd 259
- Kernels installed: 7.0.0-22.22, 7.0.0-27.27, 7.0.0-28.28
- kwin-wayland 4:6.6.5-0ubuntu0.1
- Displays: eDP-1 1920x1080 internal; DP-1 3840x2160@60 (scale 1.25); DP-4
2560x1440 present but disabled - all via a DisplayPort MST dock
ProblemType: Bug
DistroRelease: Ubuntu 26.04
Package: linux-image-7.0.0-28-generic 7.0.0-28.28
ProcVersionSignature: Ubuntu 7.0.0-28.28-generic 7.0.12
Uname: Linux 7.0.0-28-generic x86_64
ApportVersion: 2.34.1-0ubuntu0.1
Architecture: amd64
AudioDevicesInUse:
USER PID ACCESS COMMAND
/dev/snd/controlC0: landsman 3652 F.... wireplumber
/dev/snd/controlC1: landsman 3652 F.... wireplumber
/dev/snd/seq: landsman 3648 F.... pipewire
CasperMD5CheckResult: unknown
CurrentDesktop: KDE
Date: Mon Jul 27 11:41:47 2026
InstallationDate: Installed on 2025-11-28 (241 days ago)
InstallationMedia: Kubuntu 25.10 "Questing Quokka" - Release amd64 (20251007)
MachineType: LENOVO 20L6S0CE41
ProcFB: 0 i915drmfb
ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-7.0.0-28-generic
root=UUID=1de8720b-f78a-4c2f-88e1-644abfc20a1b ro i915.enable_psr=0 quiet
rd.luks.uuid=01ac2e35-53c6-4df0-b4a5-890925841fcb splash
usbcore.quirks=0bda:8153:k,0bda:5487:k,0bda:5413:k,413c:b06e:k
PulseList: Error: command ['pacmd', 'list'] failed with exit code 1: No
PulseAudio daemon running, or not running as session daemon.
SourcePackage: linux
UpgradeStatus: Upgraded to resolute on 2026-05-18 (70 days ago)
dmi.bios.date: 09/06/2025
dmi.bios.release: 1.56
dmi.bios.vendor: LENOVO
dmi.bios.version: N24ET81W (1.56 )
dmi.board.asset.tag: Not Available
dmi.board.name: 20L6S0CE41
dmi.board.vendor: LENOVO
dmi.board.version: SDK0J40697 WIN
dmi.chassis.asset.tag: No Asset Information
dmi.chassis.type: 10
dmi.chassis.vendor: LENOVO
dmi.chassis.version: None
dmi.ec.firmware.release: 1.22
dmi.modalias:
dmi:bvnLENOVO:bvrN24ET81W(1.56):bd09/06/2025:br1.56:efr1.22:svnLENOVO:pn20L6S0CE41:pvrThinkPadT480:rvnLENOVO:rn20L6S0CE41:rvrSDK0J40697WIN:cvnLENOVO:ct10:cvrNone:skuLENOVO_MT_20L6_BU_Think_FM_ThinkPadT480:pfaThinkPadT480:
dmi.product.family: ThinkPad T480
dmi.product.name: 20L6S0CE41
dmi.product.sku: LENOVO_MT_20L6_BU_Think_FM_ThinkPad T480
dmi.product.version: ThinkPad T480
dmi.sys.vendor: LENOVO
** Affects: linux (Ubuntu)
Importance: Undecided
Status: New
** Tags: amd64 apport-bug resolute wayland-session
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https://bugs.launchpad.net/bugs/2161881
Title:
[regression] i915: "Failed to open drm device" / atomic modeset EINVAL
after resume — ~12x more frequent on 7.0.0-27/-28 than 7.0.0-22
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