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yaml --- r: 308066 b: refs/heads/master c: b25b086 h: refs/heads/master v: v3
git-mirror · May 25, 2012 · e992a28 · e992a28
1 parent 2b8e101
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diff --git a/[refs] b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 12c4727e1d5370270a7df781d2ba0a76e05c1137
+refs/heads/master: b25b086d23eb852bf3cfdeb60409b4967ebb3c0c
diff --git a/trunk/Documentation/dma-buf-sharing.txt b/trunk/Documentation/dma-buf-sharing.txt
@@ -293,6 +293,17 @@ 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 cases the overhead of kmap can be too high, a vmap interface
+   is introduced. This interface should 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)
+
+   The vmap 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,