Public bug reported:
## Summary
Dell Pro Max 16 Plus laptop running Ubuntu 26.04 with Intel Meteor Lake
iGPU (`i915`) and NVIDIA RTX PRO 5000 (hybrid graphics) repeatedly
freezes with black screen(s). The system remains running (compute
continues, fans spin) but the desktop becomes completely unresponsive.
Recovery requires dock power-cycle, suspend/resume, SSH reboot, or hard
reset.
The kernel logs show repeated `i915` display driver failures in the
DPLL/PHY/pipe A path, especially during suspend/resume and display
power-state transitions. A Dell Thunderbolt 5 dock with a 5120x2160
external monitor exacerbates the issue.
Kernel parameter `i915.enable_psr=0` was applied but did not resolve
suspend/resume failures.
---
## Hardware
| Component | Details |
|---|---|
| Laptop | Dell Pro Max 16 Plus MB16250/0K8XPY |
| BIOS | 2.6.1 (03/16/2026) |
| CPU/GPU (integrated) | Intel Meteor Lake, PCI `8086:7d67`, driver `i915` |
| GPU (discrete) | NVIDIA RTX PRO 5000 Blackwell, driver `nvidia 595.71.05` |
| RAM | 128 GB |
| Internal display | eDP-1 (built-in OLED panel) |
| External monitor | Dell U4025QW 40" ultrawide, 5120x2160 |
| Dock | Dell Thunderbolt 5 Dock (SD25TB5 / K2 DOCK) |
| Dock link | TB5, 120 Gb/s, left-side Thunderbolt port |
| Monitor connection | DisplayPort (dock DP port; previously USB-C, same bug) |
---
## Software
| Component | Version |
|---|---|
| OS | Ubuntu 26.04 LTS (resolute) |
| Kernel | 7.0.0-27-generic (#27-Ubuntu SMP PREEMPT_DYNAMIC) |
| Mesa | 26.0.3-1ubuntu1 |
| libdrm | 2.4.131-1 |
| linux-firmware-intel-graphics | 20260319.git217ca6e4-0ubuntu2.1 |
| Desktop | GNOME Shell 50.1, Wayland |
| Kernel cmdline | `i915.enable_psr=0` (PSR disabled, bug persists) |
---
## Symptoms
1. One or both screens go black
2. Keyboard/mouse input stops responding
3. System is NOT fully dead — background processes (e.g. vLLM compute) may
continue
4. No clean shutdown — logs stop abruptly until hard reset or recovery action
5. Disconnecting monitor/dock during freeze does not help (compositor blocked
in kernel ioctl)
6. Toggling dock power off/on DOES recover the display link
---
## Triggers (confirmed across multiple incidents)
| Trigger | Confirmed |
|---|---|
| Suspend / resume (lid close, idle suspend) | Yes — most reliable trigger |
| Overnight idle (display power management) | Yes |
| Stopping GPU workload (vLLM exit) | Yes — likely GPU power-state change |
| External monitor via dock at 5120x2160 | Contributes — DP link retraining
failures |
| Monitor hotplug / dock reconnect | Yes |
---
## Kernel error signature (repeated in every incident)
```
i915 0000:00:02.0: [drm] *ERROR* flip_done timed out
i915 0000:00:02.0: [drm] *ERROR* [CRTC:150:pipe A] commit wait timed out
i915 0000:00:02.0: [drm] DPLL 0: pll hw state mismatch
WARNING: drivers/gpu/drm/i915/display/intel_dpll_mgr.c:4945 at
verify_single_dpll_state
WARNING: drivers/gpu/drm/i915/display/intel_modeset_verify.c:225 at
verify_crtc_state
i915 0000:00:02.0: [drm] *ERROR* Timeout waiting for DDI BUF A to get active
i915 0000:00:02.0: [drm] *ERROR* Timed out waiting for DP idle patterns
i915 0000:00:02.0: [drm] *ERROR* PHY A failed to change powerdown state
i915 0000:00:02.0: [drm] Port A PLL not unlocked
i915 0000:00:02.0: [drm] port_clock mismatch: expected 540000, found 61440
i915 0000:00:02.0: [drm] pixel_rate mismatch: expected 317250, found 36096
```
During suspend/resume, errors occur in:
- `intel_display_driver_resume` → `i915_drm_resume`
- `intel_dp_retrain_link` → `intel_encoder_link_check_work_fn`
Also seen:
```
pcieport 0000:00:01.0: PCIe Bus Error: ACSViol (Thunderbolt controller)
NVRM: RmHandleDNotifierEvent: Failed to handle ACPI D-Notifier event,
status=0x11
```
No `NMI watchdog`, `soft lockup`, or `hung_task` messages — kernel
appears alive, display commit path is deadlocked.
---
## Incident timeline
### Incident 1 — 2026-07-10 ~20:23
- Hard reset required
- Last log: `flip_done timed out` at 20:23:43
- Reboot at 20:26:48
### Incident 2 — 2026-07-11 ~10:14
- Overnight computation, spontaneous freeze (no user interaction)
- Both screens black, unresponsive
- Hard reset, reboot at 10:31:55
### Incident 3 — 2026-07-11 ~17:51
- After login, exiting vLLM
- Recovered via dock power-cycle (no hard reset)
### Incident 4 — 2026-07-12 ~10:44
- Suspend/resume (lid close)
- Same i915 errors during `i915_drm_resume`
- Recovered without hard reset (~1 minute)
---
## What was tried
| Mitigation | Result |
|---|---|
| `i915.enable_psr=0` kernel parameter | Active in cmdline; bug persists on
suspend/resume |
| Monitor USB-C → DisplayPort on dock | Display path changed (DP-7 → DP-10);
suspend/resume still fails |
| Dock on TB5 port (left side, 120 Gb/s) | Correct port confirmed; bug persists
|
| Dock power-cycle | Recovers display (workaround, not fix) |
---
## Display topology
```
Laptop (Intel i915, card1)
├── eDP-1: internal panel (always connected)
└── DP-10: external Dell U4025QW via TB5 dock DisplayPort
NVIDIA (card2): all outputs disconnected (compute only, vLLM)
```
External display is driven by **Intel i915**, not NVIDIA, even with vLLM
using the discrete GPU.
---
## Steps to reproduce
1. Dell Pro Max 16 Plus with BIOS 2.6.1
2. Connect Dell TB5 dock to left-side Thunderbolt 5 port
3. Connect Dell U4025QW (or similar 5K display) via DisplayPort on dock
4. Boot Ubuntu 26.04 with kernel 7.0.0-27-generic
5. Use dual-monitor setup (internal + external)
6. Suspend the system (close lid or `systemctl suspend`)
7. Resume
**Expected:** Normal desktop
**Actual:** Black screen(s), input frozen; kernel logs show i915 DPLL/flip_done
errors
Alternative trigger: leave system idle overnight with external monitor
connected.
** Affects: linux (Ubuntu)
Importance: Undecided
Status: New
** Attachment added: "logs"
https://bugs.launchpad.net/bugs/2160453/+attachment/5981380/+files/dell.zip
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https://bugs.launchpad.net/bugs/2160453
Title:
i915: DPLL/PHY hang on Meteor Lake (Dell Pro Max 16 Plus) with TB5
dock after suspend/resume - flip_done timeout, system freeze
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