I'm experiencing this severely on some systems with this hardware on the
6.8.0-45 kernel on Ubuntu 24.04:
00:02.0 VGA compatible controller [0300]: Intel Corporation CoffeeLake-S GT2
[UHD Graphics 630] [8086:3e92]
DeviceName: Onboard - Video
Subsystem: Dell CoffeeLake-S GT2 [UHD Graphics 630] [1028:085b]
Kernel driver in use: i915
intel_iommu=igfx does appear to work as a workaround.
--
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:
Confirmed
Status in linux source package in Noble:
Fix Committed
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
To manage notifications about this bug go to:
https://bugs.launchpad.net/linux/+bug/2062951/+subscriptions
--
Mailing list: https://launchpad.net/~kernel-packages
Post to : kernel-packages@lists.launchpad.net
Unsubscribe : https://launchpad.net/~kernel-packages
More help : https://help.launchpad.net/ListHelp
