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 <[email protected]> Cc: Christian Koenig <[email protected]> Cc: Huang Rui <[email protected]> Cc: Thomas Hellström <[email protected]> Signed-off-by: Daniel Vetter <[email protected]> --- 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
