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SubjectRe: [PATCH v2] iommu/amd: Disable IOMMU on Stoney Ridge systems
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Hi Joerg,

> On Dec 3, 2019, at 01:00, Christoph Hellwig <hch@infradead.org> wrote:
>
> On Fri, Nov 29, 2019 at 10:21:54PM +0800, Kai-Heng Feng wrote:
>> Serious screen flickering when Stoney Ridge outputs to a 4K monitor.
>>
>> According to Alex Deucher, IOMMU isn't enabled on Windows, so let's do
>> the same here to avoid screen flickering on 4K monitor.
>
> Disabling the IOMMU entirely seem pretty severe. Isn't it enough to
> identity map the GPU device?

Ok, there's set_device_exclusion_range() to exclude the device from IOMMU.
However I don't know how to generate range_start and range_length, which are read from ACPI.

Can you please give me some advice here?

Kai-Henge

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