[PATCH 1/5] drm/ttm: add a weak BO reference to the resource v2

["Christian König" <ckoenig.leichtzumerken@gmail.com>]

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

Signed-off-by: Christian König <christian.koenig@amd.com>
---
 drivers/gpu/drm/i915/intel_region_ttm.c | 5 +++++
 drivers/gpu/drm/ttm/ttm_bo_util.c       | 7 +++++--
 drivers/gpu/drm/ttm/ttm_resource.c      | 1 +
 include/drm/ttm/ttm_resource.h          | 2 ++
 4 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_region_ttm.c b/drivers/gpu/drm/i915/intel_region_ttm.c
index 27fe0668d094..980b10a7debf 100644
--- a/drivers/gpu/drm/i915/intel_region_ttm.c
+++ b/drivers/gpu/drm/i915/intel_region_ttm.c
@@ -88,6 +88,7 @@ intel_region_ttm_node_reserve(struct intel_memory_region *mem,
 	place.fpfn = offset >> PAGE_SHIFT;
 	place.lpfn = place.fpfn + (size >> PAGE_SHIFT);
 	mock_bo.base.size = size;
+	mock_bo.bdev = &mem->i915->bdev;
 	ret = man->func->alloc(man, &mock_bo, &place, &res);
 	if (ret == -ENOSPC)
 		ret = -ENXIO;
@@ -104,7 +105,11 @@ void intel_region_ttm_node_free(struct intel_memory_region *mem,
 				struct ttm_resource *res)
 {
 	struct ttm_resource_manager *man = mem->region_private;
+	struct ttm_buffer_object mock_bo = {};
 
+	mock_bo.base.size = res->num_pages * PAGE_SIZE;
+	mock_bo.bdev = &mem->i915->bdev;
+	res->bo = &mock_bo;
 	man->func->free(man, res);
 }
 
diff --git a/drivers/gpu/drm/ttm/ttm_bo_util.c b/drivers/gpu/drm/ttm/ttm_bo_util.c
index 2f57f824e6db..a1570aa8ff56 100644
--- a/drivers/gpu/drm/ttm/ttm_bo_util.c
+++ b/drivers/gpu/drm/ttm/ttm_bo_util.c
@@ -239,6 +239,11 @@ 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) {
+		fbo->base.resource->bo = &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);
@@ -507,7 +512,6 @@ 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);
@@ -635,7 +639,6 @@ 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 2431717376e7..7ff6194154fe 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);
 
diff --git a/include/drm/ttm/ttm_resource.h b/include/drm/ttm/ttm_resource.h
index 140b6b9a8bbe..c73b35fb7d42 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 using this resource
  *
  * 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;
 };
 
 /**
-- 
2.25.1