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

[Lazar, Lijo]

On 2/17/2022 9:16 AM, Mario Limonciello 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>
> ---
>   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;
> +

Doesn't this disable aspm for all devices even though only one of the 
bridges doesn't have support?

Thanks,
Lijo

>   	if (amdgpu_virtual_display ||
>   	    amdgpu_device_asic_has_dc_support(flags & AMD_ASIC_MASK))
>   		supports_atomic = true;
>