[PATCH 1/2] drm/amdgpu: remove pointless ttm_eu usage from vkms

[Alex Deucher]

On Tue, Apr 19, 2022 at 10:19 AM Christian König
<ckoenig.leichtzumerken at gmail.com> wrote:
>
> We just need to reserve the BO here, no need for using ttm_eu.

Can you include a more detailed description as to why it's not
necessary?  Most of this code was copied from radeon originally.  Does
radeon need a similar cleanup?

Alex

>
> Signed-off-by: Christian König <christian.koenig at amd.com>
> ---
>  drivers/gpu/drm/amd/amdgpu/amdgpu_vkms.c | 32 +++++++++++++-----------
>  1 file changed, 17 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vkms.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vkms.c
> index 5224d9a39737..576849e95296 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vkms.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vkms.c
> @@ -302,9 +302,6 @@ static int amdgpu_vkms_prepare_fb(struct drm_plane *plane,
>         struct drm_gem_object *obj;
>         struct amdgpu_device *adev;
>         struct amdgpu_bo *rbo;
> -       struct list_head list;
> -       struct ttm_validate_buffer tv;
> -       struct ww_acquire_ctx ticket;
>         uint32_t domain;
>         int r;
>
> @@ -316,18 +313,19 @@ static int amdgpu_vkms_prepare_fb(struct drm_plane *plane,
>         obj = new_state->fb->obj[0];
>         rbo = gem_to_amdgpu_bo(obj);
>         adev = amdgpu_ttm_adev(rbo->tbo.bdev);
> -       INIT_LIST_HEAD(&list);
>
> -       tv.bo = &rbo->tbo;
> -       tv.num_shared = 1;
> -       list_add(&tv.head, &list);
> -
> -       r = ttm_eu_reserve_buffers(&ticket, &list, false, NULL);
> +       r = amdgpu_bo_reserve(rbo, true);
>         if (r) {
>                 dev_err(adev->dev, "fail to reserve bo (%d)\n", r);
>                 return r;
>         }
>
> +       r = dma_resv_reserve_fences(rbo->tbo.base.resv, 1);
> +       if (r) {
> +               dev_err(adev->dev, "allocating fence slot failed (%d)\n", r);
> +               goto error_unlock;
> +       }
> +
>         if (plane->type != DRM_PLANE_TYPE_CURSOR)
>                 domain = amdgpu_display_supported_domains(adev, rbo->flags);
>         else
> @@ -337,25 +335,29 @@ static int amdgpu_vkms_prepare_fb(struct drm_plane *plane,
>         if (unlikely(r != 0)) {
>                 if (r != -ERESTARTSYS)
>                         DRM_ERROR("Failed to pin framebuffer with error %d\n", r);
> -               ttm_eu_backoff_reservation(&ticket, &list);
> -               return r;
> +               goto error_unlock;
>         }
>
>         r = amdgpu_ttm_alloc_gart(&rbo->tbo);
>         if (unlikely(r != 0)) {
> -               amdgpu_bo_unpin(rbo);
> -               ttm_eu_backoff_reservation(&ticket, &list);
>                 DRM_ERROR("%p bind failed\n", rbo);
> -               return r;
> +               goto error_unpin;
>         }
>
> -       ttm_eu_backoff_reservation(&ticket, &list);
> +       amdgpu_bo_unreserve(rbo);
>
>         afb->address = amdgpu_bo_gpu_offset(rbo);
>
>         amdgpu_bo_ref(rbo);
>
>         return 0;
> +
> +error_unpin:
> +       amdgpu_bo_unpin(rbo);
> +
> +error_unlock:
> +       amdgpu_bo_unreserve(rbo);
> +       return r;
>  }
>
>  static void amdgpu_vkms_cleanup_fb(struct drm_plane *plane,
> --
> 2.25.1
>