Re: [PATCH v6 05/11] amdgpu/ttm: use amdgpu_gtt_mgr_alloc_entries

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

On 1/26/26 14:35, Pierre-Eric Pelloux-Prayer wrote:
> Use amdgpu_gtt_mgr_alloc_entries for each entity instead
> of reserving a fixed number of pages.
> 
> Signed-off-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@amd.com>
> ---
>  drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c | 66 ++++++++++++++++---------
>  drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h |  1 +
>  2 files changed, 43 insertions(+), 24 deletions(-)
> 
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> index 8b38b5ed9a9c..d23d3046919b 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> @@ -2012,37 +2012,47 @@ static void amdgpu_ttm_free_mmio_remap_bo(struct amdgpu_device *adev)
>  	adev->rmmio_remap.bo = NULL;
>  }
>  
> -static int amdgpu_ttm_buffer_entity_init(struct amdgpu_ttm_buffer_entity *entity,
> +static int amdgpu_ttm_buffer_entity_init(struct amdgpu_gtt_mgr *mgr,
> +					 struct amdgpu_ttm_buffer_entity *entity,
>  					 enum drm_sched_priority prio,
>  					 struct drm_gpu_scheduler **scheds,
>  					 int num_schedulers,
> -					 int starting_gart_window,
>  					 u32 num_gart_windows)
>  {
> -	int i, r;
> +	int i, r, num_pages;
>  
>  	r = drm_sched_entity_init(&entity->base, prio, scheds, num_schedulers, NULL);
>  	if (r)
>  		return r;
>  
> -
>  	mutex_init(&entity->lock);
>  
>  	if (ARRAY_SIZE(entity->gart_window_offs) < num_gart_windows)
> -		return starting_gart_window;
> +		return -EINVAL;
> +	if (num_gart_windows == 0)
> +		return 0;
> +
> +	num_pages = num_gart_windows * AMDGPU_GTT_MAX_TRANSFER_SIZE;
> +	r = amdgpu_gtt_mgr_alloc_entries(mgr, &entity->node, num_pages,
> +					 DRM_MM_INSERT_BEST);
> +	if (r) {
> +		drm_sched_entity_destroy(&entity->base);
> +		return r;
> +	}
>  
>  	for (i = 0; i < num_gart_windows; i++) {
>  		entity->gart_window_offs[i] =
> -			(u64)starting_gart_window * AMDGPU_GTT_MAX_TRANSFER_SIZE *
> -				AMDGPU_GPU_PAGE_SIZE;
> -		starting_gart_window++;
> +			(entity->node.start + (u64)i * AMDGPU_GTT_MAX_TRANSFER_SIZE) *
> +			AMDGPU_GPU_PAGE_SIZE;

If I'm not completely mistaken the GTT manager works with PAGE_SIZE and not AMDGPU_GPU_PAGE_SIZE.

Background is that we can only map CPU pages (4k-64k) into the GTT/GART and not GPU pages (which are always 4k).

It would probably be the cleanest to have a helper for that in amdgpu_gtt_mgr.c (or a header).

Apart from that patch looks good to me,
Christian.

>  	}
>  
> -	return starting_gart_window;
> +	return 0;
>  }
>  
> -static void amdgpu_ttm_buffer_entity_fini(struct amdgpu_ttm_buffer_entity *entity)
> +static void amdgpu_ttm_buffer_entity_fini(struct amdgpu_gtt_mgr *mgr,
> +					  struct amdgpu_ttm_buffer_entity *entity)
>  {
> +	amdgpu_gtt_mgr_free_entries(mgr, &entity->node);
>  	drm_sched_entity_destroy(&entity->base);
>  }
>  
> @@ -2343,36 +2353,42 @@ void amdgpu_ttm_set_buffer_funcs_status(struct amdgpu_device *adev, bool enable)
>  
>  		ring = adev->mman.buffer_funcs_ring;
>  		sched = &ring->sched;
> -		r = amdgpu_ttm_buffer_entity_init(&adev->mman.default_entity,
> -						  DRM_SCHED_PRIORITY_KERNEL, &sched, 1,
> -						  0, 0);
> +		r = amdgpu_ttm_buffer_entity_init(&adev->mman.gtt_mgr,
> +						  &adev->mman.default_entity,
> +						  DRM_SCHED_PRIORITY_KERNEL,
> +						  &sched, 1, 0);
>  		if (r < 0) {
>  			dev_err(adev->dev,
>  				"Failed setting up TTM entity (%d)\n", r);
>  			return;
>  		}
>  
> -		r = amdgpu_ttm_buffer_entity_init(&adev->mman.clear_entity,
> -						  DRM_SCHED_PRIORITY_NORMAL, &sched, 1,
> -						  r, 1);
> +		r = amdgpu_ttm_buffer_entity_init(&adev->mman.gtt_mgr,
> +						  &adev->mman.clear_entity,
> +						  DRM_SCHED_PRIORITY_NORMAL,
> +						  &sched, 1, 1);
>  		if (r < 0) {
>  			dev_err(adev->dev,
>  				"Failed setting up TTM BO clear entity (%d)\n", r);
>  			goto error_free_default_entity;
>  		}
>  
> -		r = amdgpu_ttm_buffer_entity_init(&adev->mman.move_entity,
> -						  DRM_SCHED_PRIORITY_NORMAL, &sched, 1,
> -						  r, 2);
> +		r = amdgpu_ttm_buffer_entity_init(&adev->mman.gtt_mgr,
> +						  &adev->mman.move_entity,
> +						  DRM_SCHED_PRIORITY_NORMAL,
> +						  &sched, 1, 2);
>  		if (r < 0) {
>  			dev_err(adev->dev,
>  				"Failed setting up TTM BO move entity (%d)\n", r);
>  			goto error_free_clear_entity;
>  		}
>  	} else {
> -		amdgpu_ttm_buffer_entity_fini(&adev->mman.default_entity);
> -		amdgpu_ttm_buffer_entity_fini(&adev->mman.clear_entity);
> -		amdgpu_ttm_buffer_entity_fini(&adev->mman.move_entity);
> +		amdgpu_ttm_buffer_entity_fini(&adev->mman.gtt_mgr,
> +					      &adev->mman.default_entity);
> +		amdgpu_ttm_buffer_entity_fini(&adev->mman.gtt_mgr,
> +					      &adev->mman.clear_entity);
> +		amdgpu_ttm_buffer_entity_fini(&adev->mman.gtt_mgr,
> +					      &adev->mman.move_entity);
>  		/* Drop all the old fences since re-creating the scheduler entities
>  		 * will allocate new contexts.
>  		 */
> @@ -2390,9 +2406,11 @@ void amdgpu_ttm_set_buffer_funcs_status(struct amdgpu_device *adev, bool enable)
>  	return;
>  
>  error_free_clear_entity:
> -	amdgpu_ttm_buffer_entity_fini(&adev->mman.clear_entity);
> +	amdgpu_ttm_buffer_entity_fini(&adev->mman.gtt_mgr,
> +				      &adev->mman.clear_entity);
>  error_free_default_entity:
> -	amdgpu_ttm_buffer_entity_fini(&adev->mman.default_entity);
> +	amdgpu_ttm_buffer_entity_fini(&adev->mman.gtt_mgr,
> +				      &adev->mman.default_entity);
>  }
>  
>  static int amdgpu_ttm_prepare_job(struct amdgpu_device *adev,
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h
> index 871388b86503..5419344d60fb 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h
> @@ -56,6 +56,7 @@ struct amdgpu_gtt_mgr {
>  struct amdgpu_ttm_buffer_entity {
>  	struct drm_sched_entity base;
>  	struct mutex		lock;
> +	struct drm_mm_node	node;
>  	u64			gart_window_offs[2];
>  };
>