Public bug reported:
1) Release of Ubuntu:
Ubuntu 24.04 LTS (Noble Numbat)
2) Package Version:
linux-image-7.0.0-38-generic (Package: linux)
Regression observed between linux-image-7.0.0-31-generic (working) and
linux-image-7.0.0-38-generic (broken).
3) What you expected to happen:
When turning on the laptop without external monitors attached, the internal
screen (eDP-1) should initialize and display the GDM login screen on boot.
4) What happened instead:
On kernel 7.0.0-38-generic, the internal screen (eDP-1) backlight turns on, but
the display remains completely black. Kernel logs report:
[drm] xe 0000:00:02.0: [drm] *ERROR* CPU pipe A FIFO underrun
Hotplugging an external HDMI monitor forces an atomic display re-probe,
which resets Pipe A and immediately wakes up the eDP-1 screen.
Hardware Details:
-----------------
- Laptop: Lenovo ThinkPad P14s Gen 7
- Graphics: Intel Xe Graphics (iGPU) + NVIDIA (dGPU Hybrid mode)
- Display: Internal panel (eDP-1)
Comparative Testing:
--------------------
- Kernel 7.0.0-31-generic: eDP-1 initializes and displays normally on cold boot.
- Kernel 7.0.0-38-generic: eDP-1 consistently fails initialization with FIFO
underrun on cold boot.
Stable kernel (current): Ubuntu 7.0.0-31.31~24.04.1-generic 7.0.14
Big in kernel: Ubuntu 7.0.0-38.38~24.04.4-generic
** Affects: linux (Ubuntu)
Importance: Undecided
Status: New
** Attachment added: "lspci-vnvn.log"
https://bugs.launchpad.net/bugs/2169456/+attachment/6005472/+files/lspci-vnvn.log
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https://bugs.launchpad.net/bugs/2169456
Title:
[Regression] xe driver eDP-1 cold boot black screen (CPU pipe A FIFO
underrun) between 7.0.0-31 and 7.0.0-38
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