On 01/31/2018 03:00 PM, Greg KH wrote:
On Wed, Jan 31, 2018 at 02:03:42PM +0200, Alexey Skidanov wrote:
Any driver may access shared buffers, created by ion, using dma_buf_vmap and
dma_buf_vunmap dma-buf API that maps/unmaps previosuly allocated buffers into
the kernel virtual address space. The implementation of these API is missing in
the current ion implementation.
Signed-off-by: Alexey Skidanov <alexey.skidanov@xxxxxxxxx>
---
No review from any other Intel developers? :(
Will add.
Anyway, what in-tree driver needs access to these functions?
I'm not sure that there are the in-tree drivers using these functions
and ion as buffer exporter because they are not implemented in ion :)
But there are some in-tree drivers using these APIs (gpu drivers) with
other buffer exporters.
And are you sure that you don't need to do any "real" logic in the
vmap/vunmap calls? That feels like there would be some reference
counting problems here.
dma_buf_start_cpu_access is called before the call to dma_buf_vmap. It
actually increments the reference count. dma_buf_end_cpu_access is
called after the dma_buf_vunmap. It actually decrements the reference
count.>>
diff --git a/drivers/staging/android/ion/ion.c b/drivers/staging/android/ion/ion.c
index f480885..4f1dc7f 100644
--- a/drivers/staging/android/ion/ion.c
+++ b/drivers/staging/android/ion/ion.c
@@ -327,6 +327,17 @@ static void ion_dma_buf_kunmap(struct dma_buf *dmabuf, unsigned long offset,
{
}
+static void *ion_dma_buf_vmap(struct dma_buf *dmabuf)
+{
+ struct ion_buffer *buffer = dmabuf->priv;
+
+ return buffer->vaddr;
Just call ion_dma_buf_kmap(dmabuf, 0)?
Sure.
Again, please get this reviewed by someone else in Intel first. Don't
ignore the resources you have, to do so would be foolish :)
Sure. Will do.
thanks,
greg k-h
Thanks,
Alexey
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