[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