Motivated because I got confused and Christian confirmed why this works. I think this is non-obvious enough that it merits a slightly longer comment. Cc: Christian König <ckoenig.leichtzumerken@xxxxxxxxx> Cc: Christian Koenig <christian.koenig@xxxxxxx> Cc: Huang Rui <ray.huang@xxxxxxx> Cc: Thomas Hellström <thomas.hellstrom@xxxxxxxxxxxxxxx> Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxxx> --- drivers/gpu/drm/ttm/ttm_bo.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c index ca1b098b6a56..51a94fd63bd7 100644 --- a/drivers/gpu/drm/ttm/ttm_bo.c +++ b/drivers/gpu/drm/ttm/ttm_bo.c @@ -682,7 +682,9 @@ int ttm_mem_evict_first(struct ttm_device *bdev, } /* - * Add the last move fence to the BO and reserve a new shared slot. + * Add the last move fence to the BO and reserve a new shared slot. We only use + * a shared slot to avoid unecessary sync and rely on the subsequent bo move to + * either stall or use an exclusive fence respectively set bo->moving. */ static int ttm_bo_add_move_fence(struct ttm_buffer_object *bo, struct ttm_resource_manager *man, -- 2.31.0
