[Bug 2062951] Re: Random flickering with Intel i915 on Linux 6.8 (Ubuntu 24.04)

intel_idle.max_cstate=4 definitely not working for me so will try
intel_idle.max_cstate=2 as folks have noted and see what occurs

00:02.0 VGA compatible controller: Intel Corporation CometLake-H GT2 [UHD Graphics] (rev 05) (prog-if 00 [VGA controller])
DeviceName: Onboard IGD
Subsystem: Hewlett-Packard Company CometLake-H GT2 [UHD Graphics]
Flags: bus master, fast devsel, latency 0, IRQ 218, IOMMU group 0
Memory at df000000 (64-bit, non-prefetchable) [size=16M]
Memory at a0000000 (64-bit, prefetchable) [size=256M]
I/O ports at 3000 [size=64]
Expansion ROM at 000c0000 [virtual] [disabled] [size=128K]
Capabilities: [40] Vendor Specific Information: Len=0c <?>
Capabilities: [70] Express Root Complex Integrated Endpoint, MSI 00
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)
Kernel driver in use: i915
Kernel modules: i915

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https://bugs.launchpad.net/bugs/2062951

Title:
Random flickering with Intel i915 on Linux 6.8 (Ubuntu 24.04)

Status in linux package in Ubuntu:
Confirmed

Bug description:
After migrating Mantic 23.10 install to Linux 6.8.0, I am experiencing heavy flickering at random.
It happens after a moderate to heavy on screen activity like window switching, scrolling etc.
It never happens when playing video or when there is no interaction using keyboard/pointer.

It tend to happen when the mouse cursor is in the bottom quarter of the screen and stops immediately when the cursor leaves that screen region.
Around the same time the following appears in kernel log:
kernel: i915 0000:00:02.0: [drm] *ERROR* CPU pipe A FIFO underrun

Happens on both X11 and Wayland on both KDE plasma and Mate (though
less).

I first encountered the issue with Linux 6.8.0-11 and it still happens with Ubunutu's 6.8.0-28 and Mainline 6.8.7.
Kernels 6.6, 6.5, 6.1 and older did not have that issue.

Hardware is: Dell XPS 9350, Vendor Intel, Driver i915, Skylake GT2 [HD Graphics 520]
Software: Ubuntu 23.10, KDE Plasma 5.27.10 / Mate 1.26

Attaching kernel log for 6.8.0-28

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