[REGRESSION] Too-low frequency limit for AMD GPU PCI-passed-through to Windows VM

Jim Turner linuxkernel.foss at dmarc-none.turner.link
Sun Jan 30 00:25:07 UTC 2022

Hi Lijo,

> Specifically, I was looking for any events happening at these two
> places because of the patch-
> https://elixir.bootlin.com/linux/v5.16/source/drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c#L411
> https://elixir.bootlin.com/linux/v5.16/source/drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c#L653

I searched the logs generated with all drm debug messages enabled
(drm.debug=0x1ff) for "device_class", "ATCS", "atcs", "ATIF", and
"atif", for both f1688bd69ec4 and f9b7f3703ff9. Other than the few lines
mentioning ATIF from my previous email, there weren't any matches.

Since "device_class" didn't appear in the logs, we know that
`amdgpu_atif_handler` was not called for either version.

I also patched f9b7f3703ff9 to add the line

  DRM_DEBUG_DRIVER("Entered amdgpu_acpi_pcie_performance_request");

at the top (below the variable declarations) of
`amdgpu_acpi_pcie_performance_request`, and then tested again with all
drm debug messages enabled (0x1ff). That debug message didn't show up.

So, `amdgpu_acpi_pcie_performance_request` was not called either, at
least with f9b7f3703ff9. (I didn't try adding this patch to

Would anything else be helpful?


More information about the amd-gfx mailing list