I had strange horizontal flickering after upgrading to Ubuntu 24.10. The
intel_iommu=igfx_off option solved this for me.
❰peter❙~❱✔≻ cat /proc/cmdline
BOOT_IMAGE=/vmlinuz-6.11.0-9-generic root=/dev/mapper/vgubuntu-root ro
intel_iommu=igfx_off quiet splash
crashkernel=2G-4G:320M,4G-32G:512M,32G-64G:1024M,64G-128G:2048M,128G-:4096M
vt.handoff=7
❰peter❙~❱✔≻ uname -a
Linux peter-laptop 6.11.0-9-generic #9-Ubuntu SMP PREEMPT_DYNAMIC Mon Oct 14
13:19:59 UTC 2024 x86_64 x86_64 x86_64 GNU/Linux
❰peter❙~❱✔≻ lspci -nnk | grep -A3 VGA
00:02.0 VGA compatible controller [0300]: Intel Corporation Alder Lake-UP3 GT2
[Iris Xe Graphics] [8086:46a8] (rev 0c)
Subsystem: Dell Device [1028:0b0b]
Kernel driver in use: i915
Kernel modules: i915, xe
BIOS Information
Vendor: Dell Inc.
Version: 1.26.0
Release Date: 08/14/2024
System Information
Manufacturer: Dell Inc.
Product Name: Latitude 7430
Processor Information
Socket Designation: U3E1
Type: Central Processor
Family: Core i7
Manufacturer: Intel(R) Corporation
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You received this bug notification because you are a member of Kernel
Packages, which is subscribed to linux-hwe-6.8 in Ubuntu.
https://bugs.launchpad.net/bugs/2062951
Title:
Random flickering with Intel i915 (Gen9 GPUs in 6th-8th gen CPUs) on
Linux 6.8
Status in Linux:
New
Status in linux package in Ubuntu:
Fix Released
Status in linux-hwe-6.8 package in Ubuntu:
Invalid
Status in linux source package in Jammy:
Invalid
Status in linux-hwe-6.8 source package in Jammy:
Fix Released
Status in linux source package in Noble:
Fix Released
Status in linux-hwe-6.8 source package in Noble:
Invalid
Status in linux source package in Oracular:
Fix Released
Status in linux-hwe-6.8 source package in Oracular:
Invalid
Bug description:
SRU Justification
[Impact]
The flickering predominantly occurs when the mouse cursor is in the bottom
quarter of the screen and stops when the cursor leaves this area.
Extensive testing across various kernel versions revealed that the issue
became apparent from kernel version 6.8.0 onward, correlating with the
mentioned configuration changes, CONFIG_INTEL_IOMMU_DEFAULT_ON and
CONFIG_INTEL_IOMMU_SCALABLE_MODE_DEFAULT_ON.
The problem persists in the latest drm tip.
[Fix]
As an immediate workaround, adding 'intel_iommu=igfx_off' to the kernel
command line has been found to effectively eliminate the flickering issue.
This patch proposes the same behavior as 'intel_iommu=igfx_off' and apply the
rule to all Intel SKL GPU IDs.
[Test]
1. Boot up to desktop with 6.8.0-x kernels
2. Moving cursor around the desktop
3. There should be no flicker while cursor is moving
[Where problems could occur]
For virtualized environments using hardware-assisted virtualization for
graphics (such as VFIO or mediated pass-through), disabling IOMMU for graphics
could either disable these features or reduce their security and efficiency.
Usually, users pass the 'intel_iommu=on' by themselves when they are using
related features. So, the impact of this change is minimal.
===========
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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