[PATCH v3] drm/amdgpu: Check extended configuration space register when system uses large bar

[Christian König]

Am 10.01.24 um 11:13 schrieb Ma Jun:
> Some customer platforms do not enable mmconfig for various reasons,
> such as bios bug, and therefore cannot access the GPU extend configuration
> space through mmio.
>
> When the system enters the d3cold state and resumes, the amdgpu driver
> fails to resume because the extend configuration space registers of
> GPU can't be restored. At this point, Usually we only see some failure
> dmesg log printed by amdgpu driver, it is difficult to find the root
> cause.
>
> Therefor print a warnning message if the system can't access the
> extended configuration space register when using large bar.
>
> Signed-off-by: Ma Jun <Jun.Ma2 at amd.com>

Reviewed-by: Christian König <christian.koenig at amd.com>

> ---
> v2:
> - Check the register at 0x100 but not resize bar register
> - Modify the commit message
> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 4 ++++
>   1 file changed, 4 insertions(+)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> index 4b694696930e..629de7f2908c 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> @@ -1442,6 +1442,10 @@ int amdgpu_device_resize_fb_bar(struct amdgpu_device *adev)
>   	if (amdgpu_sriov_vf(adev))
>   		return 0;
>   
> +	/* PCI_EXT_CAP_ID_VNDR extended capability is located at 0x100 */
> +	if (!pci_find_ext_capability(adev->pdev, PCI_EXT_CAP_ID_VNDR))
> +		DRM_WARN("System can't access extended configuration space,please check!!\n");
> +
>   	/* skip if the bios has already enabled large BAR */
>   	if (adev->gmc.real_vram_size &&
>   	    (pci_resource_len(adev->pdev, 0) >= adev->gmc.real_vram_size))