Messages in this thread | | | Subject | Re: [PATCH v3] staging: android: ion: Add implementation of dma_buf_vmap and dma_buf_vunmap | From | Alexey Skidanov <> | Date | Thu, 1 Feb 2018 08:10:07 +0200 |
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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@intel.com> >> --- > > 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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