[Linaro-mm-sig] [PATCH] dma-buf: add support for kernel cpu access

[Sumit Semwal]

On 20 March 2012 04:32, Daniel Vetter <daniel.vetter at ffwll.ch> wrote:
> Big differences to other contenders in the field (like ion) is
> that this also supports highmem, so we have to split up the cpu
> access from the kernel side into a prepare and a kmap step.
>
> Prepare is allowed to fail and should do everything required so that
> the kmap calls can succeed (like swapin/backing storage allocation,
> flushing, ...).
>
> More in-depth explanations will follow in the follow-up documentation
> patch.
>
> Changes in v2:
>
> - Clear up begin_cpu_access confusion noticed by Sumit Semwal.
> - Don't automatically fallback from the _atomic variants to the
>  non-atomic variants. The _atomic callbacks are not allowed to
>  sleep, so we want exporters to make this decision explicit. The
>  function signatures are explicit, so simpler exporters can still
>  use the same function for both.
> - Make the unmap functions optional. Simpler exporters with permanent
>  mappings don't need to do anything at unmap time.
>
> Changes in v3:
>
> - Adjust the WARN_ON checks for the new ->ops functions as suggested
>  by Rob Clark and Sumit Semwal.
> - Rebased on top of latest dma-buf-next git.
>
> Changes in v4:
>
> - Fixup a missing - in a return -EINVAL; statement.
>
> Signed-Off-by: Daniel Vetter <daniel.vetter at ffwll.ch>
Thanks; applied to for-next.
> ---
<snip>
BR,
~Sumit.