Re: [PATCH] docs: dmaengine: clarify ordering rules around cookie completion

[Vinod Koul <vkoul@kernel.org>]

On 09-10-26, 14:05, Frank Li wrote:
> On Fri, Oct 09, 2026 at 11:37:44AM +0200, Vinod Koul wrote:
> > Sashiko pointed in [1] about the cookie completion order. It is good to
> > Document that for ensuring that dma buffer is flushed and no stale data
> > is seeing by consumer, we need to make sure such action is taken before
> > drivers invoke dma cookie completion.
> >
> > [1]: https://lore.kernel.org/r/20260917072507.5BDB61F000FF@smtp.kernel.org
> >
> > Signed-off-by: Vinod Koul <vkoul@kernel.org>
> > ---
> >  Documentation/driver-api/dmaengine/provider.rst | 5 +++++
> >  1 file changed, 5 insertions(+)
> >
> > diff --git a/Documentation/driver-api/dmaengine/provider.rst b/Documentation/driver-api/dmaengine/provider.rst
> > index 2897ade67b39..1bcbce705659 100644
> > --- a/Documentation/driver-api/dmaengine/provider.rst
> > +++ b/Documentation/driver-api/dmaengine/provider.rst
> > @@ -557,6 +557,11 @@ dma_cookie_t
> >  - Not really relevant any more since the introduction of ``virt-dma``
> >    that abstracts it away.
> >
> > +- dmaengine drivers need to ensure buffers are flushed before invoking
> > +  vchan_cookie_complete() or dma_cookie_complete(). This would imply a call
> > +  to unmapping buffers or any such architcure calls to ensure caller seeing
> 
> Sashiko report a typo architcure

Yeah looks like my spell checker didnt caught it, I will apply now with
that fixed

> 
> Reviewed-by: Frank Li <Frank.Li@nxp.com>
> 
> > +  buffers are flushed is done before invoking these calls.
> > +
> >  dma_vec
> >
> >  - A small structure that contains a DMA address and length.
> > --
> > 2.53.0
> >

-- 
~Vinod