[BUG] "Pre-boot DMA Protection" makes AMDGPU stop working

[Kai-Heng Feng]

Hi,

A more detailed bug report can be found at [1].

I have a AMD Renoir system that can't enter graphical session because there are many IOMMU splat.

Alex suggested to disable "Pre-boot DMA Protection", I can confirm once it's disabled, AMDGPU starts working with IOMMU enabled.
So raise the issue here because I have no knowledge on how to reset the IOMMU.

[1] https://gitlab.freedesktop.org/drm/amd/-/issues/1204

Kai-Heng