Re: [PATCH v1 12/20] drm/amdgpu: use TTM_FENCES_MAX_SLOT_COUNT

["Christian König" <christian.koenig@amd.com>]

On 11/4/25 09:35, Pierre-Eric Pelloux-Prayer wrote:
> Use TTM_FENCES_MAX_SLOT_COUNT as an upperbound of how many fences
> ttm might need to deal with moves/evictions.
> 
> Signed-off-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@amd.com>
> ---
>  drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c                  | 5 ++---
>  drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c                 | 2 +-
>  drivers/gpu/drm/amd/amdgpu/amdgpu_vkms.c                | 2 +-
>  drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c                  | 3 ++-
>  drivers/gpu/drm/amd/amdkfd/kfd_svm.c                    | 2 +-
>  drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_plane.c | 2 +-
>  drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_wb.c    | 2 +-
>  7 files changed, 9 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
> index ecdfe6cb36cc..b232ed28872b 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
> @@ -916,9 +916,8 @@ static int amdgpu_cs_parser_bos(struct amdgpu_cs_parser *p,
>  			goto out_free_user_pages;
>  
>  		amdgpu_bo_list_for_each_entry(e, p->bo_list) {
> -			/* One fence for TTM and one for each CS job */
>  			r = drm_exec_prepare_obj(&p->exec, &e->bo->tbo.base,
> -						 1 + p->gang_size);
> +						 TTM_FENCES_MAX_SLOT_COUNT + p->gang_size);
>  			drm_exec_retry_on_contention(&p->exec);
>  			if (unlikely(r))
>  				goto out_free_user_pages;
> @@ -928,7 +927,7 @@ static int amdgpu_cs_parser_bos(struct amdgpu_cs_parser *p,
>  
>  		if (p->uf_bo) {
>  			r = drm_exec_prepare_obj(&p->exec, &p->uf_bo->tbo.base,
> -						 1 + p->gang_size);
> +						 TTM_FENCES_MAX_SLOT_COUNT + p->gang_size);
>  			drm_exec_retry_on_contention(&p->exec);
>  			if (unlikely(r))
>  				goto out_free_user_pages;
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
> index ce073e894584..f773b06dd135 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
> @@ -353,7 +353,7 @@ static void amdgpu_gem_object_close(struct drm_gem_object *obj,
>  
>  	drm_exec_init(&exec, DRM_EXEC_IGNORE_DUPLICATES, 0);
>  	drm_exec_until_all_locked(&exec) {
> -		r = drm_exec_prepare_obj(&exec, &bo->tbo.base, 1);
> +		r = drm_exec_prepare_obj(&exec, &bo->tbo.base, TTM_FENCES_MAX_SLOT_COUNT);
>  		drm_exec_retry_on_contention(&exec);
>  		if (unlikely(r))
>  			goto out_unlock;
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vkms.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vkms.c
> index 79bad9cbe2ab..d9bb16186e1f 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vkms.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vkms.c
> @@ -326,7 +326,7 @@ static int amdgpu_vkms_prepare_fb(struct drm_plane *plane,
>  		return r;
>  	}
>  
> -	r = dma_resv_reserve_fences(rbo->tbo.base.resv, 1);
> +	r = dma_resv_reserve_fences(rbo->tbo.base.resv, TTM_FENCES_MAX_SLOT_COUNT);
>  	if (r) {
>  		dev_err(adev->dev, "allocating fence slot failed (%d)\n", r);

While at it please also drop this error message. It is absolutely not helpful at all.

>  		goto error_unlock;
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
> index 2f8e83f840a8..bc11e212f08c 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
> @@ -2630,7 +2630,8 @@ int amdgpu_vm_init(struct amdgpu_device *adev, struct amdgpu_vm *vm,
>  	}
>  
>  	amdgpu_vm_bo_base_init(&vm->root, vm, root_bo);
> -	r = dma_resv_reserve_fences(root_bo->tbo.base.resv, 1);
> +	r = dma_resv_reserve_fences(root_bo->tbo.base.resv,
> +				    TTM_FENCES_MAX_SLOT_COUNT);
>  	if (r)
>  		goto error_free_root;
>  
> diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_svm.c b/drivers/gpu/drm/amd/amdkfd/kfd_svm.c
> index ffb7b36e577c..ea8dd17e2852 100644
> --- a/drivers/gpu/drm/amd/amdkfd/kfd_svm.c
> +++ b/drivers/gpu/drm/amd/amdkfd/kfd_svm.c
> @@ -627,7 +627,7 @@ svm_range_vram_node_new(struct kfd_node *node, struct svm_range *prange,
>  		}
>  	}
>  
> -	r = dma_resv_reserve_fences(bo->tbo.base.resv, 1);
> +	r = dma_resv_reserve_fences(bo->tbo.base.resv, TTM_FENCES_MAX_SLOT_COUNT);
>  	if (r) {
>  		pr_debug("failed %d to reserve bo\n", r);

Same here.

>  		amdgpu_bo_unreserve(bo);
> diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_plane.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_plane.c
> index 56cb866ac6f8..1f2a5dcfa3e5 100644
> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_plane.c
> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_plane.c
> @@ -952,7 +952,7 @@ static int amdgpu_dm_plane_helper_prepare_fb(struct drm_plane *plane,
>  		return r;
>  	}
>  
> -	r = dma_resv_reserve_fences(rbo->tbo.base.resv, 1);
> +	r = dma_resv_reserve_fences(rbo->tbo.base.resv, TTM_FENCES_MAX_SLOT_COUNT);
>  	if (r) {
>  		drm_err(adev_to_drm(adev), "reserving fence slot failed (%d)\n", r);

And here.

>  		goto error_unlock;
> diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_wb.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_wb.c
> index d9527c05fc87..60b57d213bdd 100644
> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_wb.c
> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_wb.c
> @@ -106,7 +106,7 @@ static int amdgpu_dm_wb_prepare_job(struct drm_writeback_connector *wb_connector
>  		return r;
>  	}
>  
> -	r = dma_resv_reserve_fences(rbo->tbo.base.resv, 1);
> +	r = dma_resv_reserve_fences(rbo->tbo.base.resv, TTM_FENCES_MAX_SLOT_COUNT);
>  	if (r) {
>  		drm_err(adev_to_drm(adev), "reserving fence slot failed (%d)\n", r);

And here.

Regards,
Christian.

>  		goto error_unlock;