[PATCH 1/3] drm/amd: Fix detection of _PR3 on the PCIe root port

[Deucher, Alexander]

[Public]

> -----Original Message-----
> From: Limonciello, Mario <Mario.Limonciello at amd.com>
> Sent: Tuesday, September 26, 2023 7:00 PM
> To: amd-gfx at lists.freedesktop.org; Sebastian Reichel <sre at kernel.org>;
> Deucher, Alexander <Alexander.Deucher at amd.com>
> Cc: linux-pm at vger.kernel.org; linux-kernel at vger.kernel.org; Ma, Jun
> <Jun.Ma2 at amd.com>; Limonciello, Mario <Mario.Limonciello at amd.com>
> Subject: [PATCH 1/3] drm/amd: Fix detection of _PR3 on the PCIe root port
>
> On some systems with Navi3x dGPU will attempt to use BACO for runtime PM
> but fails to resume properly.  This is because on these systems the root port
> goes into D3cold which is incompatible with BACO.
>
> This happens because in this case dGPU is connected to a bridge between root
> port which causes BOCO detection logic to fail.  Fix the intent of the logic by
> looking at root port, not the immediate upstream bridge for _PR3.
>
> Cc: stable at vger.kernel.org
> Suggested-by: Jun Ma <Jun.Ma2 at amd.com>
> Tested-by: David Perry <David.Perry at amd.com>
> Fixes: b10c1c5b3a4e ("drm/amdgpu: add check for ACPI power resources")
> Signed-off-by: Mario Limonciello <mario.limonciello at amd.com>

Series is:
Reviewed-by: Alex Deucher <alexander.deucher at amd.com>

> ---
>  drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> index e4627d92e1d0..bad2b5577e96 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> @@ -2238,7 +2238,7 @@ static int amdgpu_device_ip_early_init(struct
> amdgpu_device *adev)
>               adev->flags |= AMD_IS_PX;
>
>       if (!(adev->flags & AMD_IS_APU)) {
> -             parent = pci_upstream_bridge(adev->pdev);
> +             parent = pcie_find_root_port(adev->pdev);
>               adev->has_pr3 = parent ? pci_pr3_present(parent) : false;
>       }
>
> --
> 2.34.1