[PATCH 2/2] drm/amdgpu: Advise if unable to resize BAR

[Alex Deucher]

On Thu, May 21, 2020 at 4:45 PM Alan Swanson <reiver at improbability.net> wrote:
>
> Even with the "Above 4G decoding" (or similar) BIOS option enabled,
> many BIOS do not assign the PCI root bus a 64-bit address space.
>
> If available, "MMIOH Base" and "MMIO High Size" (or similar) BIOS
> options should allow mapping to the desired address spaces.
>
> Signed-off-by: Alan Swanson <reiver at improbability.net>
> ---
> Useful to know why bar resizing isn't happening.

This will spam a lot of people and probably cause confusion.  I'd
prefer to drop this one.

Alex


>
>  drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> index 2f0e8da7b..39a7f7212 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> @@ -919,8 +919,10 @@ int amdgpu_device_resize_fb_bar(struct amdgpu_device *adev)
>         }
>
>         /* Trying to resize is pointless without a root hub window above 4GB */
> -       if (!res)
> +       if (!res) {
> +               DRM_INFO("Unable to resize BAR as PCI bus address space below 4GB.");
>                 return 0;
> +       }
>
>         /* Disable memory decoding while we change the BAR addresses and size */
>         pci_read_config_word(adev->pdev, PCI_COMMAND, &cmd);
> --
> 2.26.2
>
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