Flapping connection to 2nd monitor due to FIFO underrun after Standby | Ubuntu & ARC B580

[MrMoonshine]

Hello,

I'm currently facing an issue with a 2nd with my ARC B580 card. If the PC goes into standby or hibernate, the 2nd monitor is failing.

The monitor connection to the video-card is flapping. It looks like a connection is being established and a couple of seconds later it'll disconnect again. Rebooting fixes it. Dmesg logs show FIFO underrun simultanously to the flaps.

There is a workaround without rebooting however: Setting a different resolution and set it back again. This helps to recover the 2nd monitor.

Does anyone else have this issue and maybe also fixed? Thanks in advance.

System Info:

Operating System: Ubuntu 24.10
KDE Plasma Version: 6.1.5
KDE Frameworks Version: 6.6.0
Qt Version: 6.6.2
Kernel Version: 6.11.0-24-generic (64-bit)
Graphics Platform: Wayland
Processors: 28 × Intel® Core™ i7-14700F
Memory: 30.6 GiB of RAM
Graphics Processor: Mesa Intel® Graphics
Manufacturer: ASRock
Product Name: B760M Pro RS

*Same behaviour also seen on the default-gnome desktop of Ubuntu. Therefore KDE/SDDM issue can be ruled out.

Inxi & Dmesg:

:~$ inxi --graphics
Graphics:
 Device-1: Intel Battlemage G21 [Intel Graphics] driver: xe v: kernel
 Display: wayland server: X.org v: 1.21.1.13 with: Xwayland v: 24.1.2
   compositor: kwin_wayland driver: X: loaded: modesetting unloaded: fbdev,vesa
   dri: iris gpu: xe resolution: 1: 1080x1920 2: 1920x1080
 API: EGL v: 1.5 drivers: iris,swrast
   platforms: gbm,wayland,x11,surfaceless,device
 API: OpenGL v: 4.6 compat-v: 4.5 vendor: intel mesa
   v: 24.2.8-1ubuntu1~24.10.1 renderer: Mesa Intel Graphics (BMG G21)
 API: Vulkan v: 1.3.290 drivers: N/A surfaces: xcb,xlib,wayland

# dmesg -T | grep drm | tail -n 5
[Di Apr 29 22:25:26 2025] xe 0000:03:00.0: [drm] *ERROR* CPU pipe A FIFO underrun: port,transcoder,
[Di Apr 29 22:25:35 2025] xe 0000:03:00.0: [drm] *ERROR* CPU pipe A FIFO underrun: port,transcoder,
[Di Apr 29 22:25:44 2025] xe 0000:03:00.0: [drm] *ERROR* CPU pipe A FIFO underrun: port,transcoder,
[Di Apr 29 22:25:44 2025] xe 0000:03:00.0: [drm] *ERROR* CPU pipe A FIFO underrun: port,transcoder,
[Di Apr 29 22:25:53 2025] xe 0000:03:00.0: [drm] *ERROR* CPU pipe A FIFO underrun: port,transcoder,

Regards,

David

[VonM_Intel]

Hi, MrMoonshine.

Thank you for highlighting this issue in our community. You're certainly not alone. What you're describing aligns with a known problem involving FIFO underruns on Intel ARC GPUs (including the B580) when resuming from standby or hibernate states, particularly under certain versions of the Linux kernel and associated drivers. The root cause typically stems from a combination of DP link training instability post-resume and how the display engine handles timing recovery, leading to repeated FIFO underruns and link flapping. Your observation that switching resolutions temporarily resolves the issue is consistent with re-triggering the mode set pipeline, essentially forcing a reinitialization of the link. To effectively diagnose and triage this issue, I’d like to gather the following:

• How is the second monitor connected? (e.g., HDMI, DisplayPort, USB-C, dongle/adapter involved?)
• Does the issue occur every time the system resumes from standby, or is it intermittent?
• Is the primary display affected at all, or only the second monitor?
• Does switching the monitor's cable or port affect the behavior?
• When changing the resolution to recover the monitor, are you doing it manually or via script?
• Did this behavior start after a recent update to the kernel, firmware, or Mesa stack?

Additionally, if possible, please share a video demonstrating the flapping connection issue with the second monitor. This will help me perform a more thorough analysis.

Have a nice day!

Best regards,

Von M.

Intel Customer Support Technician

[VonM_Intel]

Hello, MrMoonshine.

Have you had a chance to review my previous response? Please let us know if you require any further assistance. I'm here to help.

Best regards,

Von M.

Intel Customer Support Technician

[VonM_Intel]

Hello, MrMoonshine.

I have not heard back from you, so I will close this inquiry now. If you need further assistance, please submit a new question as this thread will no longer be monitored.

Best regards,

Von M.

Intel Customer Support Technician