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

AMD General

Reviewed-by: Candice Li <[email protected]>


Thanks,
Candice

-----Original Message-----
From: Wang, Yang(Kevin) <[email protected]>
Sent: Wednesday, August 12, 2026 4:09 PM
To: [email protected]
Cc: Deucher, Alexander <[email protected]>; Zhang, Hawking <[email protected]>; Feng, Kenneth <[email protected]>; Li, Candice <[email protected]>
Subject: [PATCH] drm/amdgpu: Disable runtime PM for externally attached dGPUs

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.

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