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

[Dave Jiang <dave.jiang@intel.com>]

On 10/9/26 2:37 AM, 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>

Reviewed-by: Dave Jiang <dave.jiang@intel.com>

> ---
>  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
> +  buffers are flushed is done before invoking these calls.
> +
>  dma_vec
>  
>  - A small structure that contains a DMA address and length.