APPLIED(E)/cmt: [SRU] [B/E/F/Unstable] [PATCH 0/1] Fix AMD Stoney Ridge screen flickering under 4K resolution

[Khaled Elmously]

This does NOT apply cleanly to Bionic. It's a minior conflict in logging syntax, but I don't know what syntax is preferred or if it's important, so I can't resolve it:

https://pastebin.canonical.com/p/GqjmKvc72N/



Applied to E only.



On 2020-02-20 16:37:02 , Kai-Heng Feng wrote:
> BugLink: https://bugs.launchpad.net/bugs/1864005
> 
> [Impact]
> Screen flickering/tearing when AMD Stoney Ridge outputs to 4K display.
> 
> [Fix]
> Disable IOMMU on Stoney Ridge.
> 
> [Test]
> Connect to 4K screen through DP or HDMI. Heavy flickering/tearing can be
> observed.
> The flickering/tearing is gone once the patch is applied.
> 
> [Regression Potential]
> Low. This fix limits to one specific SoC.
> According to AMD, IOMMU isn't enabled for this SoC under Windows.
> So it's expected behavior.
> 
> Kai-Heng Feng (1):
>   iommu/amd: Disable IOMMU on Stoney Ridge systems
> 
>  drivers/iommu/amd_iommu_init.c | 13 ++++++++++++-
>  1 file changed, 12 insertions(+), 1 deletion(-)
> 
> -- 
> 2.17.1
> 
> 
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