drm/amdgpu: prefer VMIDs idle on the current ring

Prefer to use a VMIDs which are idle on the ring we want to submit to. This
also removes bubbling idle VMIDs up on the LRU, which is actually not
beneficial.
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Christian König <christian.koenig@amd.com>
Acked-by: Chunming Zhou <david1.zhou@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c

@@ -236,21 +236,15 @@ int amdgpu_vm_grab_id(struct amdgpu_vm *vm, struct amdgpu_ring *ring,
 
 	} while (i != ring->idx);
 
-	id = list_first_entry(&adev->vm_manager.ids_lru,
-			      struct amdgpu_vm_id,
-			      list);
-
-	if (!amdgpu_sync_is_idle(&id->active, NULL)) {
-		struct list_head *head = &adev->vm_manager.ids_lru;
-		struct amdgpu_vm_id *tmp;
+	/* Check if we have an idle VMID */
+	list_for_each_entry(id, &adev->vm_manager.ids_lru, list) {
+		if (amdgpu_sync_is_idle(&id->active, ring))
+			break;
 
-		list_for_each_entry_safe(id, tmp, &adev->vm_manager.ids_lru,
-					 list) {
-			if (amdgpu_sync_is_idle(&id->active, NULL)) {
-				list_move(&id->list, head);
-				head = &id->list;
-			}
 	}
+
+	/* If we can't find a idle VMID to use, just wait for the oldest */
+	if (&id->list == &adev->vm_manager.ids_lru) {
 		id = list_first_entry(&adev->vm_manager.ids_lru,
 				      struct amdgpu_vm_id,
 				      list);