To allow a smooth transition from pinning buffer objects to dynamic
invalidation we first start to cache the sg_table for an attachment
unless the driver explicitly says to not do so.
Signed-off-by: Christian König <christian.koenig@xxxxxxx>
---
drivers/dma-buf/dma-buf.c | 24 ++++++++++++++++++++++++
include/linux/dma-buf.h | 11 +++++++++++
2 files changed, 35 insertions(+)
diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
index 13884474d158..0bea5eecf554 100644
--- a/drivers/dma-buf/dma-buf.c
+++ b/drivers/dma-buf/dma-buf.c
@@ -574,6 +574,20 @@ struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf,
list_add(&attach->node, &dmabuf->attachments);
mutex_unlock(&dmabuf->lock);
+
+ if (!dmabuf->ops->no_sgt_cache) {
+ 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:
@@ -596,6 +610,10 @@ 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)
@@ -631,6 +649,9 @@ 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);
@@ -658,6 +679,9 @@ 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..6534a6769e17 100644
--- a/include/linux/dma-buf.h
+++ b/include/linux/dma-buf.h
@@ -51,6 +51,16 @@ struct dma_buf_attachment;
* @vunmap: [optional] unmaps a vmap from the buffer
*/
struct dma_buf_ops {
+ /**
+ * @no_sgt_cache:
+ *
+ * Flag controlling the caching of the sg_table in the DMA-buf helpers.
+ * If not set the sg_table is created during device attaching, if set
+ * the sg_table is created dynamically when dma_buf_map_attachment() is
+ * called.
+ */
+ bool no_sgt_cache;
+
/**
* @attach:
*
@@ -323,6 +333,7 @@ struct dma_buf_attachment {
struct device *dev;
struct list_head node;
void *priv;
+ struct sg_table *sgt;
};
/**
--
2.14.1
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