[PATCH 01/11] drm/ttm: add ttm_bo_pin()/ttm_bo_unpin() v2

[Huang Rui]

On Tue, Sep 22, 2020 at 09:31:58PM +0800, Christian König wrote:
> As an alternative to the placement flag add a
> pin count to the ttm buffer object.
> 
> v2: add dma_resv_assert_help() calls
> 
> Signed-off-by: Christian König <christian.koenig at amd.com>

Series look good for me as well.

Reviewed-by: Huang Rui <ray.huang at amd.com>

Only one comment:

We can modify the TOPDOWN offset as 21 since the NO_EVICT is removed.

 #define TTM_PL_FLAG_UNCACHED    (1 << 17)
 #define TTM_PL_FLAG_WC          (1 << 18)
 #define TTM_PL_FLAG_CONTIGUOUS  (1 << 19)
-#define TTM_PL_FLAG_NO_EVICT    (1 << 21)
 #define TTM_PL_FLAG_TOPDOWN     (1 << 22)

Thanks,
Ray

> ---
>  drivers/gpu/drm/ttm/ttm_bo.c      |  9 ++++++---
>  drivers/gpu/drm/ttm/ttm_bo_util.c |  2 +-
>  include/drm/ttm/ttm_bo_api.h      | 26 ++++++++++++++++++++++++++
>  3 files changed, 33 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
> index 70b3bee27850..b82b49d43942 100644
> --- a/drivers/gpu/drm/ttm/ttm_bo.c
> +++ b/drivers/gpu/drm/ttm/ttm_bo.c
> @@ -115,7 +115,7 @@ static void ttm_bo_add_mem_to_lru(struct ttm_buffer_object *bo,
>  	struct ttm_bo_device *bdev = bo->bdev;
>  	struct ttm_resource_manager *man;
>  
> -	if (!list_empty(&bo->lru))
> +	if (!list_empty(&bo->lru) || bo->pin_count)
>  		return;
>  
>  	if (mem->placement & TTM_PL_FLAG_NO_EVICT)
> @@ -165,7 +165,8 @@ void ttm_bo_move_to_lru_tail(struct ttm_buffer_object *bo,
>  	ttm_bo_del_from_lru(bo);
>  	ttm_bo_add_mem_to_lru(bo, &bo->mem);
>  
> -	if (bulk && !(bo->mem.placement & TTM_PL_FLAG_NO_EVICT)) {
> +	if (bulk && !(bo->mem.placement & TTM_PL_FLAG_NO_EVICT) &&
> +	    !bo->pin_count) {
>  		switch (bo->mem.mem_type) {
>  		case TTM_PL_TT:
>  			ttm_bo_bulk_move_set_pos(&bulk->tt[bo->priority], bo);
> @@ -544,8 +545,9 @@ static void ttm_bo_release(struct kref *kref)
>  		 * shrinkers, now that they are queued for
>  		 * destruction.
>  		 */
> -		if (bo->mem.placement & TTM_PL_FLAG_NO_EVICT) {
> +		if (bo->mem.placement & TTM_PL_FLAG_NO_EVICT || bo->pin_count) {
>  			bo->mem.placement &= ~TTM_PL_FLAG_NO_EVICT;
> +			bo->pin_count = 0;
>  			ttm_bo_del_from_lru(bo);
>  			ttm_bo_add_mem_to_lru(bo, &bo->mem);
>  		}
> @@ -1172,6 +1174,7 @@ int ttm_bo_init_reserved(struct ttm_bo_device *bdev,
>  	bo->moving = NULL;
>  	bo->mem.placement = TTM_PL_FLAG_CACHED;
>  	bo->acc_size = acc_size;
> +	bo->pin_count = 0;
>  	bo->sg = sg;
>  	if (resv) {
>  		bo->base.resv = resv;
> diff --git a/drivers/gpu/drm/ttm/ttm_bo_util.c b/drivers/gpu/drm/ttm/ttm_bo_util.c
> index fb2a25f8408f..1968df9743fc 100644
> --- a/drivers/gpu/drm/ttm/ttm_bo_util.c
> +++ b/drivers/gpu/drm/ttm/ttm_bo_util.c
> @@ -352,7 +352,6 @@ static int ttm_buffer_object_transfer(struct ttm_buffer_object *bo,
>  		return -ENOMEM;
>  
>  	fbo->base = *bo;
> -	fbo->base.mem.placement |= TTM_PL_FLAG_NO_EVICT;
>  
>  	ttm_bo_get(bo);
>  	fbo->bo = bo;
> @@ -372,6 +371,7 @@ static int ttm_buffer_object_transfer(struct ttm_buffer_object *bo,
>  	kref_init(&fbo->base.kref);
>  	fbo->base.destroy = &ttm_transfered_destroy;
>  	fbo->base.acc_size = 0;
> +	fbo->base.pin_count = 1;
>  	if (bo->type != ttm_bo_type_sg)
>  		fbo->base.base.resv = &fbo->base.base._resv;
>  
> diff --git a/include/drm/ttm/ttm_bo_api.h b/include/drm/ttm/ttm_bo_api.h
> index 0f7cd21d6d74..33aca60870e2 100644
> --- a/include/drm/ttm/ttm_bo_api.h
> +++ b/include/drm/ttm/ttm_bo_api.h
> @@ -157,6 +157,7 @@ struct ttm_buffer_object {
>  
>  	struct dma_fence *moving;
>  	unsigned priority;
> +	unsigned pin_count;
>  
>  	/**
>  	 * Special members that are protected by the reserve lock
> @@ -606,6 +607,31 @@ static inline bool ttm_bo_uses_embedded_gem_object(struct ttm_buffer_object *bo)
>  	return bo->base.dev != NULL;
>  }
>  
> +/**
> + * ttm_bo_pin - Pin the buffer object.
> + * @bo: The buffer object to pin
> + *
> + * Make sure the buffer is not evicted any more during memory pressure.
> + */
> +static inline void ttm_bo_pin(struct ttm_buffer_object *bo)
> +{
> +	dma_resv_assert_held(bo->base.resv);
> +	++bo->pin_count;
> +}
> +
> +/**
> + * ttm_bo_unpin - Unpin the buffer object.
> + * @bo: The buffer object to unpin
> + *
> + * Allows the buffer object to be evicted again during memory pressure.
> + */
> +static inline void ttm_bo_unpin(struct ttm_buffer_object *bo)
> +{
> +	dma_resv_assert_held(bo->base.resv);
> +	WARN_ON_ONCE(!bo->pin_count);
> +	--bo->pin_count;
> +}
> +
>  int ttm_mem_evict_first(struct ttm_bo_device *bdev,
>  			struct ttm_resource_manager *man,
>  			const struct ttm_place *place,
> -- 
> 2.17.1
>