On Wed, Nov 24, 2021 at 08:44:21PM +0800, Christian König wrote:
> Keep track for which BO a resource was allocated.
> This is necessary to move the LRU handling into the resources.
>
> A bit problematic is i915 since it tries to use the resource
> interface without a BO which is illegal from the conceptional
> point of view.
>
> v2: Document that this is a weak reference and add a workaround for i915
> v3: further document that this is protected by ttm_device::lru_lock and
> clarify the i915 workaround
>
> Signed-off-by: Christian König <christian.koenig@xxxxxxx>
> ---
> drivers/gpu/drm/ttm/ttm_bo_util.c | 7 +++++--
> drivers/gpu/drm/ttm/ttm_resource.c | 9 +++++++++
> include/drm/ttm/ttm_resource.h | 4 ++++
> 3 files changed, 18 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/ttm/ttm_bo_util.c b/drivers/gpu/drm/ttm/ttm_bo_util.c
> index 95de2691ee7c..a2e3a9626198 100644
> --- a/drivers/gpu/drm/ttm/ttm_bo_util.c
> +++ b/drivers/gpu/drm/ttm/ttm_bo_util.c
> @@ -237,6 +237,11 @@ static int ttm_buffer_object_transfer(struct ttm_buffer_object *bo,
> if (bo->type != ttm_bo_type_sg)
> fbo->base.base.resv = &fbo->base.base._resv;
>
> + if (fbo->base.resource) {
> + ttm_resource_set_bo(fbo->base.resource, &fbo->base);
> + bo->resource = NULL;
> + }
> +
> dma_resv_init(&fbo->base.base._resv);
> fbo->base.base.dev = NULL;
> ret = dma_resv_trylock(&fbo->base.base._resv);
> @@ -512,7 +517,6 @@ static int ttm_bo_move_to_ghost(struct ttm_buffer_object *bo,
> ghost_obj->ttm = NULL;
> else
> bo->ttm = NULL;
> - bo->resource = NULL;
>
> dma_resv_unlock(&ghost_obj->base._resv);
> ttm_bo_put(ghost_obj);
> @@ -637,7 +641,6 @@ int ttm_bo_pipeline_gutting(struct ttm_buffer_object *bo)
> dma_resv_unlock(&ghost->base._resv);
> ttm_bo_put(ghost);
> bo->ttm = ttm;
> - bo->resource = NULL;
> ttm_bo_assign_mem(bo, sys_res);
> return 0;
>
> diff --git a/drivers/gpu/drm/ttm/ttm_resource.c b/drivers/gpu/drm/ttm/ttm_resource.c
> index 41e7bf195168..7fdd58b53c61 100644
> --- a/drivers/gpu/drm/ttm/ttm_resource.c
> +++ b/drivers/gpu/drm/ttm/ttm_resource.c
> @@ -41,6 +41,7 @@ void ttm_resource_init(struct ttm_buffer_object *bo,
> res->bus.offset = 0;
> res->bus.is_iomem = false;
> res->bus.caching = ttm_cached;
> + res->bo = bo;
> }
> EXPORT_SYMBOL(ttm_resource_init);
>
> @@ -122,6 +123,14 @@ bool ttm_resource_compat(struct ttm_resource *res,
> }
> EXPORT_SYMBOL(ttm_resource_compat);
>
> +void ttm_resource_set_bo(struct ttm_resource *res,
How about rename it as ttm_resource_set_bo_with_lru_locked?
It's just a minor suggestion.
Acked-by: Huang Rui <ray.huang@xxxxxxx>
> + struct ttm_buffer_object *bo)
> +{
> + spin_lock(&bo->bdev->lru_lock);
> + res->bo = bo;
> + spin_unlock(&bo->bdev->lru_lock);
> +}
> +
> /**
> * ttm_resource_manager_init
> *
> diff --git a/include/drm/ttm/ttm_resource.h b/include/drm/ttm/ttm_resource.h
> index 6bf37383002b..69eea9d6399b 100644
> --- a/include/drm/ttm/ttm_resource.h
> +++ b/include/drm/ttm/ttm_resource.h
> @@ -161,6 +161,7 @@ struct ttm_bus_placement {
> * @mem_type: Resource type of the allocation.
> * @placement: Placement flags.
> * @bus: Placement on io bus accessible to the CPU
> + * @bo: weak reference to the BO, protected by ttm_device::lru_lock
> *
> * Structure indicating the placement and space resources used by a
> * buffer object.
> @@ -171,6 +172,7 @@ struct ttm_resource {
> uint32_t mem_type;
> uint32_t placement;
> struct ttm_bus_placement bus;
> + struct ttm_buffer_object *bo;
> };
>
> /**
> @@ -271,6 +273,8 @@ int ttm_resource_alloc(struct ttm_buffer_object *bo,
> void ttm_resource_free(struct ttm_buffer_object *bo, struct ttm_resource **res);
> bool ttm_resource_compat(struct ttm_resource *res,
> struct ttm_placement *placement);
> +void ttm_resource_set_bo(struct ttm_resource *res,
> + struct ttm_buffer_object *bo);
>
> void ttm_resource_manager_init(struct ttm_resource_manager *man,
> struct ttm_device *bdev,
> --
> 2.25.1
>
