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

[Thorsten Leemhuis]

Top-posting for once, to make this easy accessible to everyone.

Nothing happened here for two weeks now afaics. Was the discussion moved
elsewhere or did it fall through the cracks?

Ciao, Thorsten (wearing his 'the Linux kernel's regression tracker' hat)

P.S.: As the Linux kernel's regression tracker I'm getting a lot of
reports on my table. I can only look briefly into most of them and lack
knowledge about most of the areas they concern. I thus unfortunately
will sometimes get things wrong or miss something important. I hope
that's not the case here; if you think it is, don't hesitate to tell me
in a public reply, it's in everyone's interest to set the public record
straight.

On 30.01.22 01:25, Jim Turner wrote:
> 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
> f1688bd69ec4.)
> 
> Would anything else be helpful?