[libcamera-devel] [PATCH] libcamera: raspberrypi: Document vc_sm_cma pointer sharing with IPA

[Laurent Pinchart]

Hi Niklas,

Thank you for the patch.

On Mon, Jun 29, 2020 at 06:33:47PM +0200, Niklas Söderlund wrote:
> Sharing a pointer with the IPA is fragile as it will not work with all
> IPC mechanisms. Document that it's a temporary workaround that should be
> reworked.
> 
> Signed-off-by: Niklas Söderlund <niklas.soderlund at ragnatech.se>
> ---
>  src/libcamera/pipeline/raspberrypi/raspberrypi.cpp | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp b/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
> index 9d887b706c3f9670..6d7143162f0645bb 100644
> --- a/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
> +++ b/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
> @@ -1014,6 +1014,10 @@ int PipelineHandlerRPi::configureIPA(Camera *camera)
>  		/*
>  		 * The vcsm allocation will always be in the memory region
>  		 * < 32-bits to allow Videocore to access the memory.
> +		 *
> +		 * \todo Sending a pointer to the IPA is a workaround for
> +		 * vc_sm_cma not yet supporting dmabuf. This is fragile and
> +		 * should be reworked as soon as vc_sm_cma permits.

I'd say s/This is fragile/This will not work with IPA module isolation/
and maybe s/as soon as vc_sm_cma permits/when vc_sma_cma will permit/ as
we don't have to make it sound like it's the end of the world :-)

Reviewed-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>

>  		 */
>  		IPAOperationData op;
>  		op.operation = RPI_IPA_EVENT_LS_TABLE_ALLOCATION;

-- 
Regards,

Laurent Pinchart