Public bug reported:
== Environment ==
CPU/GPU: Intel Alder Lake P (i915, device ID 46a6)
Connection: USB-C to DisplayPort (external monitor)
Session: Wayland (GNOME)
Kernel broken: 6.17.0-23-generic
Kernel working: 6.17.0-22-generic
== Description ==
After upgrading to kernel 6.17.0-23-generic, the external monitor
connected via USB-C to DisplayPort is no longer detected. The system
boots and runs normally on the internal display only. Booting into
6.17.0-22-generic restores the external display immediately with no
other changes, confirming this is a regression introduced in -23.
== Symptoms ==
- xrandr shows only "None-1" (dummy connector) instead of DP-1/DP-2
- xrandr --listproviders returns 0 providers
- Logging in via Xorg session fails silently on -23
- External monitor works normally on another machine via HDMI,
ruling out hardware/cable failure
== Relevant dmesg on 6.17.0-23 ==
[6.317793] i915 0000:00:02.0: [drm] [ENCODER:261:DDI A/PHY A] failed to
retrieve link info, disabling eDP
[6.344129] i915 0000:00:02.0: [drm] Cannot find any crtc or sizes
== Bisect ==
6.17.0-22-generic → WORKS
6.17.0-23-generic → BROKEN
== Workaround ==
Booting into 6.17.0-22-generic and pinning it via GRUB_DEFAULT.
** Affects: linux (Ubuntu)
Importance: Undecided
Status: New
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https://bugs.launchpad.net/bugs/2152128
Title:
i915 Alder Lake P: USB-C DisplayPort output not detected on 6.17.0-23,
regression from 6.17.0-22
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