On Tue, May 07, 2019 at 10:13:30AM +0200, Christian König wrote:
> To allow a smooth transition from pinning buffer objects to dynamic
> invalidation we first start to cache the sg_table for an attachment.
>
> Signed-off-by: Christian König <christian.koenig@xxxxxxx>
> ---
> drivers/dma-buf/dma-buf.c | 24 ++++++++++++++++++++++++
> include/linux/dma-buf.h | 14 ++++++++++++++
> 2 files changed, 38 insertions(+)
>
> diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
> index 7c858020d14b..775e13f54083 100644
> --- a/drivers/dma-buf/dma-buf.c
> +++ b/drivers/dma-buf/dma-buf.c
> @@ -573,6 +573,20 @@ struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf,
> list_add(&attach->node, &dmabuf->attachments);
>
> mutex_unlock(&dmabuf->lock);
> +
> + if (!dma_buf_is_dynamic(dmabuf)) {
> + struct sg_table *sgt;
> +
> + sgt = dmabuf->ops->map_dma_buf(attach, DMA_BIDIRECTIONAL);
> + if (!sgt)
> + sgt = ERR_PTR(-ENOMEM);
> + if (IS_ERR(sgt)) {
> + dma_buf_detach(dmabuf, attach);
> + return ERR_CAST(sgt);
> + }
> + attach->sgt = sgt;
> + }
> +
> return attach;
>
> err_attach:
> @@ -595,6 +609,10 @@ void dma_buf_detach(struct dma_buf *dmabuf, struct dma_buf_attachment *attach)
> if (WARN_ON(!dmabuf || !attach))
> return;
>
> + if (attach->sgt)
> + dmabuf->ops->unmap_dma_buf(attach, attach->sgt,
> + DMA_BIDIRECTIONAL);
> +
> mutex_lock(&dmabuf->lock);
> list_del(&attach->node);
> if (dmabuf->ops->detach)
> @@ -630,6 +648,9 @@ struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *attach,
> if (WARN_ON(!attach || !attach->dmabuf))
> return ERR_PTR(-EINVAL);
>
> + if (attach->sgt)
> + return attach->sgt;
> +
> sg_table = attach->dmabuf->ops->map_dma_buf(attach, direction);
> if (!sg_table)
> sg_table = ERR_PTR(-ENOMEM);
> @@ -657,6 +678,9 @@ void dma_buf_unmap_attachment(struct dma_buf_attachment *attach,
> if (WARN_ON(!attach || !attach->dmabuf || !sg_table))
> return;
>
> + if (attach->sgt == sg_table)
> + return;
> +
> attach->dmabuf->ops->unmap_dma_buf(attach, sg_table,
> direction);
> }
> diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h
> index 58725f890b5b..52031fdc75bb 100644
> --- a/include/linux/dma-buf.h
> +++ b/include/linux/dma-buf.h
> @@ -322,6 +322,7 @@ struct dma_buf_attachment {
> struct dma_buf *dmabuf;
> struct device *dev;
> struct list_head node;
> + struct sg_table *sgt;
> void *priv;
> };
>
> @@ -373,6 +374,19 @@ static inline void get_dma_buf(struct dma_buf *dmabuf)
> get_file(dmabuf->file);
> }
>
> +/**
> + * dma_buf_is_dynamic - check if a DMA-buf uses dynamic mappings.
> + * @dmabuf: the DMA-buf to check
> + *
> + * Returns true if a DMA-buf exporter wants to create dynamic sg table mappings
> + * for each attachment. False if only a single static sg table should be used.
> + */
> +static inline bool dma_buf_is_dynamic(struct dma_buf *dmabuf)
> +{
> + /* Always use a static mapping for now */
> + return false;
Hm I still expect that later on we'll want this to be decided by the
attachment: It's only dynamic if both the exporter and the importer
support dynamic dma-buf management, otherwise we need to pin.
But anyway, I feel like we need to go over the entire thing anyway once
more when p2p has landed, on this:
Reviewed-by: Daniel Vetter <daniel.vetter@xxxxxxxx>
> +}
> +
> struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf,
> struct device *dev);
> void dma_buf_detach(struct dma_buf *dmabuf,
> --
> 2.17.1
>
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> dri-devel@xxxxxxxxxxxxxxxxxxxxx
> https://lists.freedesktop.org/mailman/listinfo/dri-devel
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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