| Message ID | 1337690078-5277-1-git-send-email-airlied@gmail.com |
|---|---|
| State | Accepted |
| Commit | b25b086d23eb852bf3cfdeb60409b4967ebb3c0c |
| Headers | show |
On Tue, 22 May 2012 13:34:38 +0100, Dave Airlie <airlied@gmail.com> wrote: > From: Dave Airlie <airlied@redhat.com> Inline comment for one sentence that made no sense. > Signed-off-by: Dave Airlie <airlied@redhat.com> > --- > 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 This interface should be used carefully. Sparingly would also be appropriate, though in less regular usage than carefully. > + 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
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,