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From 24f3f95fdf7b3a7c38fb5cc2e3a0e5c6dcafd989 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Christian=20K=C3=B6nig?= <christian.koenig@amd.com>
Date: Tue, 3 Jul 2018 16:42:26 +0200
Subject: [PATCH 1997/2940] dma-buf: start caching of sg_table objects v2
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
To allow a smooth transition from pinning buffer objects to dynamic
invalidation we first start to cache the sg_table for an attachment.
v2: keep closer to the DRM implementation
Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
---
drivers/dma-buf/dma-buf.c | 27 +++++++++++++++++++++++++--
include/linux/dma-buf.h | 13 +++++++++++++
2 files changed, 38 insertions(+), 2 deletions(-)
diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
index 13884474d158..63f12c3125f2 100644
--- a/drivers/dma-buf/dma-buf.c
+++ b/drivers/dma-buf/dma-buf.c
@@ -574,6 +574,7 @@ struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf,
list_add(&attach->node, &dmabuf->attachments);
mutex_unlock(&dmabuf->lock);
+
return attach;
err_attach:
@@ -596,6 +597,9 @@ 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, attach->dir);
+
mutex_lock(&dmabuf->lock);
list_del(&attach->node);
if (dmabuf->ops->detach)
@@ -631,10 +635,27 @@ 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) {
+ /*
+ * Two mappings with different directions for the same
+ * attachment are not allowed.
+ */
+ if (attach->dir != direction &&
+ attach->dir != DMA_BIDIRECTIONAL)
+ return ERR_PTR(-EBUSY);
+
+ return attach->sgt;
+ }
+
sg_table = attach->dmabuf->ops->map_dma_buf(attach, direction);
if (!sg_table)
sg_table = ERR_PTR(-ENOMEM);
+ if (!IS_ERR(sg_table) && attach->dmabuf->ops->cache_sgt_mapping) {
+ attach->sgt = sg_table;
+ attach->dir = direction;
+ }
+
return sg_table;
}
EXPORT_SYMBOL_GPL(dma_buf_map_attachment);
@@ -658,8 +679,10 @@ void dma_buf_unmap_attachment(struct dma_buf_attachment *attach,
if (WARN_ON(!attach || !attach->dmabuf || !sg_table))
return;
- attach->dmabuf->ops->unmap_dma_buf(attach, sg_table,
- direction);
+ if (attach->sgt == sg_table)
+ return;
+
+ attach->dmabuf->ops->unmap_dma_buf(attach, sg_table, direction);
}
EXPORT_SYMBOL_GPL(dma_buf_unmap_attachment);
diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h
index 58725f890b5b..45b9767e67ec 100644
--- a/include/linux/dma-buf.h
+++ b/include/linux/dma-buf.h
@@ -51,6 +51,15 @@ struct dma_buf_attachment;
* @vunmap: [optional] unmaps a vmap from the buffer
*/
struct dma_buf_ops {
+ /**
+ * @cache_sgt_mapping:
+ *
+ * If true the framework will cache the first mapping made for each
+ * attachment. This avoids creating mappings for attachments multiple
+ * times.
+ */
+ bool cache_sgt_mapping;
+
/**
* @attach:
*
@@ -307,6 +316,8 @@ struct dma_buf {
* @dmabuf: buffer for this attachment.
* @dev: device attached to the buffer.
* @node: list of dma_buf_attachment.
+ * @sgt: cached mapping.
+ * @dir: direction of cached mapping.
* @priv: exporter specific attachment data.
*
* This structure holds the attachment information between the dma_buf buffer
@@ -322,6 +333,8 @@ struct dma_buf_attachment {
struct dma_buf *dmabuf;
struct device *dev;
struct list_head node;
+ struct sg_table *sgt;
+ enum dma_data_direction dir;
void *priv;
};
--
2.17.1
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