| Message ID | 20210519082409.672016-1-daniel.vetter@ffwll.ch (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | drm/ttm: Explain why ttm_bo_add_move_fence uses a shared slot | expand |
Am 19.05.21 um 10:24 schrieb Daniel Vetter: > 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@gmail.com> > Cc: Christian Koenig <christian.koenig@amd.com> > Cc: Huang Rui <ray.huang@amd.com> > Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com> > Signed-off-by: Daniel Vetter <daniel.vetter@intel.com> Reviewed-by: Christian König <christian.koenig@amd.com> > --- > 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,
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@gmail.com> > Cc: Christian Koenig <christian.koenig@amd.com> > Cc: Huang Rui <ray.huang@amd.com> > Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com> > Signed-off-by: Daniel Vetter <daniel.vetter@intel.com> Acked-by: Huang Rui <ray.huang@amd.com> > --- > 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 >
On Wed, May 19, 2021 at 12:43:49PM +0200, Christian König wrote: > Am 19.05.21 um 10:24 schrieb Daniel Vetter: > > 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@gmail.com> > > Cc: Christian Koenig <christian.koenig@amd.com> > > Cc: Huang Rui <ray.huang@amd.com> > > Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com> > > Signed-off-by: Daniel Vetter <daniel.vetter@intel.com> > > Reviewed-by: Christian König <christian.koenig@amd.com> Applied to drm-misc-next, thanks for reviewing. -Daniel > > > --- > > 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, >
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,
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@gmail.com> Cc: Christian Koenig <christian.koenig@amd.com> Cc: Huang Rui <ray.huang@amd.com> Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com> Signed-off-by: Daniel Vetter <daniel.vetter@intel.com> --- drivers/gpu/drm/ttm/ttm_bo.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)