Re: [PATCH] drm/amdgpu: Disable runtime PM for externally attached dGPUs

On Wed, Aug 12, 2026 at 4:45 AM Yang Wang <[email protected]> wrote:
>
> pci_is_thunderbolt_attached() requires an upstream PCI bridge with
> is_thunderbolt set from an Intel Thunderbolt VSEC. This does not cover
> the affected ASM4242 USB4 PCI hierarchy:
>
>   00:02.2
>     \- 0f:00.0 [1b21:2421]
>        +- 10:01.0 [1b21:2423] -> 45:00.0 -> 46:00.0
>        |  -> 47:00.0 -> 48:00.0 -> 49:00.0 [1002:7590]
>        \- 10:03.0 -> 76:00.0 [1b21:2425] USB4 Host Router
>
> The host router is outside the GPU upstream bridge chain, leaving no
> ancestor with is_thunderbolt set. PCI core propagates DEVICE_REMOVABLE
> below the external-facing PCIe tunnel. Disable Runtime PM when either
> pci_is_thunderbolt_attached() or dev_is_removable() is true.
>

I could see BOCO being an issue, but shouldn't BACO work?  That should
be self contained to the driver.

Alex

> Signed-off-by: Yang Wang <[email protected]>
> ---
>  drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 7 +++++++
>  1 file changed, 7 insertions(+)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> index 8ebe24d59ab6..a4b4f9645c84 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> @@ -609,6 +609,13 @@ void amdgpu_device_detect_runtime_pm_mode(struct amdgpu_device *adev)
>         int bamaco_support;
>
>         adev->pm.rpm_mode = AMDGPU_RUNPM_NONE;
> +       if (pci_is_thunderbolt_attached(adev->pdev) ||
> +           dev_is_removable(&adev->pdev->dev)) {
> +               dev_info(adev->dev,
> +                        "Runtime PM disabled for externally attached device\n");
> +               return;
> +       }
> +
>         bamaco_support = amdgpu_device_supports_baco(adev);
>
>         switch (amdgpu_runtime_pm) {
> --
> 2.54.0
>