Re: [PATCH 03/12] drm/ttm: add a weak BO reference to the resource v3

On 11/24/21 13:44, 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.

s/conceptional/conceptual/ ?

Can't find the i915 workaround below? Was this the mock bo that was used in the selftest code, perhaps that was replaced with allowing resource->bo to be NULL. In that case the commit message should be updated.

/Thomas.

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@amd.com

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,

• 	 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,