one of the external monitors randomly blank for 2-3 seconds with 6.8/6.9 Linux kernels
I have a Dell Precision 5570 laptop with 2 external monitors connected via the Thunderbolt WD22TB4 dock. I'm using Debian/unstable with Linux kernels provided by Debian (but they do not have any patches to the i915 driver or DRM core).
Starting with the 6.8.* and 6.9.* kernels (at least from 6.8.11 to 6.9.12), one of these monitors (not always the same one) randomly gets blank for 2-3 seconds. This occurs up to several times a day. This is a regression, as whenever I downgrade to the 6.7.12 kernel, this issue never occurs (earlier kernels were fine too).
Number of times I could notice this issue (but I am not always in front of the screens, and note that it started more than one month earlier than my first records below):
- 2024-06-29: 4× (6.9.7 kernel)
- 2024-06-30: 1× (6.9.7 kernel)
- 2024-07-01: 1× (6.9.7 kernel)
- 2024-07-19: 3× (6.9.9 kernel)
- 2024-07-20: 3× (6.9.9 kernel)
- 2024-07-21: 4× (6.9.9 kernel)
- 2024-07-22: 3× (6.9.9 kernel)
- 2024-07-23: 1× (6.9.9 kernel)
- 2024-07-25: 3× (6.9.9 kernel)
- 2024-07-26: 1× (6.9.9 kernel)
- 2024-08-02: 3× (6.9.12 kernel)
There is nothing in the journal (journalctl
output) at the time such blanking occurs. Both monitors were blanked at the same time only once (while I was active on the laptop, so that this was not the usual DPMS off after 10 or 15 minutes of inactivity); otherwise, only one of the monitors gets blanked.
Information about the system:
-
Linux qaa 6.9.12-amd64 #1 SMP PREEMPT_DYNAMIC Debian 6.9.12-1 (2024-07-27) x86_64 GNU/Linux
(when using the current Debian kernel). - PCI device information:
# lspci -vnn -d ':*:0300'
0000:00:02.0 VGA compatible controller [0300]: Intel Corporation Alder Lake-P GT2 [Iris Xe Graphics] [8086:46a6] (rev 0c) (prog-if 00 [VGA controller])
Subsystem: Dell Device [1028:0b1a]
Flags: bus master, fast devsel, latency 0, IRQ 126, IOMMU group 0
Memory at 6188000000 (64-bit, non-prefetchable) [size=16M]
Memory at 4000000000 (64-bit, prefetchable) [size=256M]
I/O ports at 4000 [size=64]
Expansion ROM at 000c0000 [virtual] [disabled] [size=128K]
Capabilities: [40] Vendor Specific Information: Len=0c <?>
Capabilities: [70] Express Root Complex Integrated Endpoint, IntMsgNum 0
Capabilities: [ac] MSI: Enable+ Count=1/1 Maskable+ 64bit-
Capabilities: [d0] Power Management version 2
Capabilities: [100] Process Address Space ID (PASID)
Capabilities: [200] Address Translation Service (ATS)
Capabilities: [300] Page Request Interface (PRI)
Capabilities: [320] Single Root I/O Virtualization (SR-IOV)
Kernel driver in use: i915
Kernel modules: i915
- Machine: Dell Precision 5570 laptop
- I'll try to get dmesg with debug information later (anyway, the "Attach a file or image" button has currently no effect).
Additional details:
- The dock is connected to the laptop with USB-C. The monitors are connected to the dock, one with DisplayPort, one with HDMI (for xrandr, this is DP-2-1 and DP-2-3 respectively).
- Desktop environment: none (FVWM 2.7 window manager under X11).
Note that about this issue, I had reported Debian bug 1072063 on 2024-05-28. After a search on the web, I could find that this seems to be the same issue as the one reported at: https://github.com/pop-os/pop/issues/3261 (and the user also noticed it after an upgrade to a 6.8 kernel).