APPLIED[N]: [PATCH 0/1][SRU][N][O] Random flickering with Intel i915 (Gen9 GPUs) on Linux 6.8 (Ubuntu 24.04)

[Stefan Bader]

On 12.08.24 08:28, AceLan Kao wrote:
> From: "Chia-Lin Kao (AceLan)" <acelan.kao at canonical.com>
> 
> BugLink: https://bugs.launchpad.net/bugs/2062951
> 
> [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.
> 
> Chia-Lin Kao (AceLan) (1):
>    UBUNTU: SAUCE: iommu/intel: disable DMAR for SKL integrated gfx
> 
>   drivers/iommu/intel/iommu.c | 27 +++++++++++++++++++++++++++
>   1 file changed, 27 insertions(+)
> 

Applied to noble:linux/master-next. Thanks.

-Stefan

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