[PATCH 1/2] drm/amdgpu: resize VRAM BAR for CPU access on gfx10

[Alex Deucher]

On Thu, May 21, 2020 at 4:48 PM Alan Swanson <reiver at improbability.net> wrote:
>
> Try to resize BAR0 to let CPU access all of VRAM on Navi. Syncs
> code with previous gfx generations from commit d6895ad39f3b39
> ("drm/amdgpu: resize VRAM BAR for CPU access v6").
>
> Signed-off-by: Alan Swanson <reiver at improbability.net>

Tested and applied.  Thanks!

Alex

> ---
> Unfortunately cannot test this with my RX5700 on my AMD X470
> motherboard as its BIOS "Above 4G decoding" option does not
> remap the PCI root bus. Trying "pci=nocrs" also unsuccessful.
> However, I assume it's just absent due to missed commit
> overlap during gfx10 bring up and should work.
>
>  drivers/gpu/drm/amd/amdgpu/gmc_v10_0.c | 14 ++++++++++----
>  1 file changed, 10 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/gmc_v10_0.c b/drivers/gpu/drm/amd/amdgpu/gmc_v10_0.c
> index edaa50d85..ba2b7ac0c 100644
> --- a/drivers/gpu/drm/amd/amdgpu/gmc_v10_0.c
> +++ b/drivers/gpu/drm/amd/amdgpu/gmc_v10_0.c
> @@ -686,17 +686,23 @@ static void gmc_v10_0_vram_gtt_location(struct amdgpu_device *adev,
>   */
>  static int gmc_v10_0_mc_init(struct amdgpu_device *adev)
>  {
> -       /* Could aper size report 0 ? */
> -       adev->gmc.aper_base = pci_resource_start(adev->pdev, 0);
> -       adev->gmc.aper_size = pci_resource_len(adev->pdev, 0);
> +       int r;
>
>         /* size in MB on si */
>         adev->gmc.mc_vram_size =
>                 adev->nbio.funcs->get_memsize(adev) * 1024ULL * 1024ULL;
>         adev->gmc.real_vram_size = adev->gmc.mc_vram_size;
> -       adev->gmc.visible_vram_size = adev->gmc.aper_size;
> +
> +       if (!(adev->flags & AMD_IS_APU)) {
> +               r = amdgpu_device_resize_fb_bar(adev);
> +               if (r)
> +                       return r;
> +       }
> +       adev->gmc.aper_base = pci_resource_start(adev->pdev, 0);
> +       adev->gmc.aper_size = pci_resource_len(adev->pdev, 0);
>
>         /* In case the PCI BAR is larger than the actual amount of vram */
> +       adev->gmc.visible_vram_size = adev->gmc.aper_size;
>         if (adev->gmc.visible_vram_size > adev->gmc.real_vram_size)
>                 adev->gmc.visible_vram_size = adev->gmc.real_vram_size;
>
> --
> 2.26.2
>
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