[PATCH] drm/amd: Check if ASPM is enabled from PCIe subsystem

[Alex Deucher]

On Wed, Feb 16, 2022 at 10:46 PM Mario Limonciello
<mario.limonciello at amd.com> wrote:
>
> commit 0064b0ce85bb ("drm/amd/pm: enable ASPM by default") enabled ASPM
> by default but a variety of hardware configurations it turns out that this
> caused a regression.
>
> * PPC64LE hardware does not support ASPM at a hardware level.
>   CONFIG_PCIEASPM is often disabled on these architectures.
> * Some dGPUs on ALD platforms don't work with ASPM enabled and PCIe
>   subsystem disables it
>
> Check with the PCIe subsystem to see that ASPM has been enabled
> or not.
>
> Fixes: 0064b0ce85bb ("drm/amd/pm: enable ASPM by default")
> Link: https://wiki.raptorcs.com/w/images/a/ad/P9_PHB_version1.0_27July2018_pub.pdf
> Link: https://gitlab.freedesktop.org/drm/amd/-/issues/1723
> Link: https://gitlab.freedesktop.org/drm/amd/-/issues/1739
> Link: https://gitlab.freedesktop.org/drm/amd/-/issues/1885
> Link: https://gitlab.freedesktop.org/drm/amd/-/issues/1907
> Tested-by: koba.ko at canonical.com
> Signed-off-by: Mario Limonciello <mario.limonciello at amd.com>

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

> ---
>  drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
> index 5acd0473ed01..d2548fab51c5 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
> @@ -2008,6 +2008,9 @@ static int amdgpu_pci_probe(struct pci_dev *pdev,
>                         return -ENODEV;
>         }
>
> +       if (amdgpu_aspm == -1 && !pcie_aspm_enabled(pdev))
> +               amdgpu_aspm = 0;
> +
>         if (amdgpu_virtual_display ||
>             amdgpu_device_asic_has_dc_support(flags & AMD_ASIC_MASK))
>                 supports_atomic = true;
> --
> 2.25.1
>