[PATCH 1/2] drm/amdgpu/gmc: add a way to force a particular placement for GART

[Alex Deucher]

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On Thu, Sep 21, 2023 at 5:46 PM Alex Deucher <alexander.deucher at amd.com> wrote:
>
> We normally place GART based on the location of VRAM and the
> available address space around that, but provide an option
> to force a particular location for hardware that needs it.
>
> Signed-off-by: Alex Deucher <alexander.deucher at amd.com>
> ---
>  drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.c | 19 +++++++++++++++----
>  drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.h |  8 ++++++++
>  2 files changed, 23 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.c
> index f74a51a93ebb..d1d98488373b 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.c
> @@ -287,11 +287,22 @@ void amdgpu_gmc_gart_location(struct amdgpu_device *adev, struct amdgpu_gmc *mc)
>                 mc->gart_size = max(size_bf, size_af);
>         }
>
> -       if ((size_bf >= mc->gart_size && size_bf < size_af) ||
> -           (size_af < mc->gart_size))
> -               mc->gart_start = 0;
> -       else
> +       switch (mc->gart_placement) {
> +       case AMDGPU_GART_PLACEMENT_HIGH:
>                 mc->gart_start = max_mc_address - mc->gart_size + 1;
> +               break;
> +       case AMDGPU_GART_PLACEMENT_LOW:
> +               mc->gart_start = 0;
> +               break;
> +       case AMDGPU_GART_PLACEMENT_BEST_FIT:
> +       default:
> +               if ((size_bf >= mc->gart_size && size_bf < size_af) ||
> +                   (size_af < mc->gart_size))
> +                       mc->gart_start = 0;
> +               else
> +                       mc->gart_start = max_mc_address - mc->gart_size + 1;
> +               break;
> +       }
>
>         mc->gart_start &= ~(four_gb - 1);
>         mc->gart_end = mc->gart_start + mc->gart_size - 1;
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.h
> index dd0ede75e5d7..fcef057b9213 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.h
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.h
> @@ -199,6 +199,12 @@ struct amdgpu_mem_partition_info {
>
>  #define INVALID_PFN    -1
>
> +enum amdgpu_gart_placement {
> +       AMDGPU_GART_PLACEMENT_BEST_FIT = 0,
> +       AMDGPU_GART_PLACEMENT_HIGH,
> +       AMDGPU_GART_PLACEMENT_LOW,
> +};
> +
>  struct amdgpu_gmc {
>         /* FB's physical address in MMIO space (for CPU to
>          * map FB). This is different compared to the agp/
> @@ -339,6 +345,8 @@ struct amdgpu_gmc {
>         bool flush_tlb_needs_extra_type_0;
>         bool flush_tlb_needs_extra_type_2;
>         bool flush_pasid_uses_kiq;
> +
> +       enum amdgpu_gart_placement gart_placement;
>  };
>
>  #define amdgpu_gmc_emit_flush_gpu_tlb(r, vmid, addr) (r)->adev->gmc.gmc_funcs->emit_flush_gpu_tlb((r), (vmid), (addr))
> --
> 2.41.0
>