On Wed, May 19, 2021 at 04:24:09PM +0800, Daniel Vetter wrote: > 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> Acked-by: Huang Rui <ray.huang@xxxxxxx> > --- > 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 >
