From: Dave Airlie <airlied@xxxxxxxxxx>
Signed-off-by: Dave Airlie <airlied@xxxxxxxxxx>
---
Documentation/dma-buf-sharing.txt | 11 +++++++++++
1 files changed, 11 insertions(+), 0 deletions(-)
diff --git a/Documentation/dma-buf-sharing.txt b/Documentation/dma-buf-sharing.txt
index 3bbd5c5..98e9fa0 100644
--- a/Documentation/dma-buf-sharing.txt
+++ b/Documentation/dma-buf-sharing.txt
@@ -300,6 +300,17 @@ Access to a dma_buf from the kernel context involves three steps:
Note that these calls need to always succeed. The exporter needs to complete
any preparations that might fail in begin_cpu_access.
+ For some circumstances the overhead of kmap can be too high, a vmap interface
+ is introduced. This interface shouldn't be used very carefully, as vmalloc
+ space is a limited resources on many architectures.
+
+ Interfaces:
+ void *dma_buf_vmap(struct dma_buf *dmabuf)
+ void dma_buf_vunmap(struct dma_buf *dmabuf, void *vaddr)
+
+ This call can fail if there is no vmap support in the exporter, or if it
+ runs out of vmalloc space. Fallback to kmap should be implemented.
+
3. Finish access
When the importer is done accessing the range specified in begin_cpu_access,
--
1.7.6
_______________________________________________
dri-devel mailing list
dri-devel@xxxxxxxxxxxxxxxxxxxxx
http://lists.freedesktop.org/mailman/listinfo/dri-devel
