Bug 2418757 - [Regression] Kernel 6.17.9: amdgpu LTTPR error causes Green Screen/KWin crash on wake (Ryzen 9950X)
Summary: [Regression] Kernel 6.17.9: amdgpu LTTPR error causes Green Screen/KWin crash...
Keywords:
Status: NEW
Alias: None
Product: Fedora
Classification: Fedora
Component: kernel
Version: 43
Hardware: x86_64
OS: Linux
unspecified
urgent
Target Milestone: ---
Assignee: Justin M. Forbes
QA Contact: Fedora Extras Quality Assurance
URL:
Whiteboard:
: 2418758 (view as bug list)
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2025-12-04 02:08 UTC by ney
Modified: 2025-12-08 22:10 UTC (History)
16 users (show)

Fixed In Version:
Clone Of:
Environment:
Last Closed:
Type: ---
Embargoed:


Attachments (Terms of Use)

Description ney 2025-12-04 02:08:23 UTC
1. Please describe the problem:

After updating from kernel 6.17.8 to 6.17.9 on Fedora 43, the system experiences a hard crash (solid green screens) upon waking from S3 sleep or during boot initialization of the graphical session (Wayland).



4. Can you reproduce this issue? If so, please provide the steps to reproduce
   the issue below:

Steps to Reproduce:

Boot into Kernel 6.17.9-300.fc43.x86_64.

Allow system to suspend (S3).

Wake system.

Actual Results: Monitors turn solid green. KWin crashes repeatedly. The system is unresponsive.


5. Does this problem occur with the latest Rawhide kernel? To install the
   Rawhide kernel, run ``sudo dnf install fedora-repos-rawhide`` followed by
   ``sudo dnf update --enablerepo=rawhide kernel``:

No ... Never did this

6. Are you running any modules that not shipped with directly Fedora's kernel?:

Nothing which shouzdl affect the kernel ( Ghostty Terminal, Yazi, ASE ... )

7. Please attach the kernel logs. You can get the complete kernel log
   for a boot with ``journalctl --no-hostname -k > dmesg.txt``. If the
   issue occurred on a previous boot, use the journalctl ``-b`` flag.

kernel: ACPI: PM: Waking up from system sleep state S3
...
kernel: amdgpu 0000:0d:00.0: [drm] *ERROR* LTTPR count is nonzero but invalid lane count reported. Assuming no LTTPR present.
kernel: amdgpu 0000:0d:00.0: [drm] *ERROR* lttpr_caps phy_repeater_cnt is 0x0, forcing it to 0x80.
...
kwin_wayland[2495]: Atomic modeset test failed! Permission denied
kwin_wayland[2495]: Failed to create framebuffer: Invalid argument


The LTTPR error is present in the logs of the working kernel (6.17.8) but is non-fatal. In 6.17.9, the same error sequence leads to an immediate KWin crash.


Reproducible: Always

Comment 1 ney 2025-12-04 16:29:43 UTC
*** Bug 2418758 has been marked as a duplicate of this bug. ***

Comment 2 Alper 2025-12-05 15:44:03 UTC
Same bug on amd ryzen 7735HS cpu 
igpu didn't work on this kernel (6.17.9)

I retun 6.17.8

Comment 3 ney 2025-12-08 22:10:44 UTC
I have found a workaround that isolates the issue.

By moving all monitors (HDMI/DP) to the discrete NVIDIA GPU and leaving the
AMD iGPU ports empty, the system is stable on Kernel 6.17.9.

Observations:
1. The system wakes from S3 sleep without crashing.
2. The `amdgpu` LTTPR errors (previously present even in working kernels)
   have completely disappeared from the logs.

This suggests the regression is triggered specifically by the AMD display
driver's link training sequence during wake/initialization, rather than a
general ACPI/power management failure.


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