[Linaro-mm-sig] [RFC] dma-shared-buf: Add buffer sharing framework

[Clark, Rob]

On Thu, Sep 8, 2011 at 10:55 AM, Daniel Vetter <daniel at ffwll.ch> wrote:
> On Thu, Sep 08, 2011 at 08:45:43PM +0530, Sumit Semwal wrote:
>> On 8 September 2011 19:48, Clark, Rob <rob at ti.com> wrote:
>> > actually, all I think we needed was to add 'struct device *'  to
>> > get_scatterlist (and maybe doesn't hurt for put)..  I'm not entirely
>> > sure why we need create/attach_device?  The create fxn especially
>> > seems wrong.. what if you are the 2nd device to import the buffer?
>> >
>> Ah... I guess I misunderstood your 'it seems like a sane approach' to mean
>> you agree with the 2-step process suggested by Daniel :) - my bad!
>
> On re-reading Rob's response I think there's a misunderstanding. I don't
> want a create function in the dma_buf_ops. The create would be a generic
> dma_buf subsystem function that (like in the patch) allocates the struct
> and properly registers the fd and what not else. The attach_device would
> then be the only new function in dma_buf_ops.
>
> The confusion probably stems from my other proposal to hide these function
> pointers behind small inline helpers for the in-kernel api.

I guess/assume that what you are trying to get to is a way to
differentiate between "I am done DMA'ing to the buffer now, but will
likely use it again (ie. feel free to cache the mapping)", and "I am
done forever w/ the buffer (don't bother caching)"?

BR,
-R

> -Daniel
> --
> Daniel Vetter
> Mail: daniel at ffwll.ch
> Mobile: +41 (0)79 365 57 48
>