Re: [PATCH v7 20/27] v4l: subdev: add V4L2_SUBDEV_ROUTE_FL_SOURCE

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Tomi,

Thank you for the patch.

On Mon, May 24, 2021 at 01:44:01PM +0300, Tomi Valkeinen wrote:
> Add route flag to indicate that the route is a source route. This means
> that the route does not lead anywhere, and the sink_pad and sink_stream
> should not be used.

I don't like this much. It's not a route if it doesn't lead anywhere, so
this flag seems like a hack. If we need a way to discover streams on a
source, I'd rather have an explicit operation to do so. Can't the get
frame descriptor operation be used for this ?

If the need is to find out that we're reaching the end of a pipeline
while going through links and routes, I'd rather have a pad flag to
indicate that the pad is an endpoint.

> A sensor which provides multiple streams should implement get_routing
> and use the flag to mark the routes as sources.
> 
> Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
> ---
>  include/uapi/linux/v4l2-subdev.h | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/include/uapi/linux/v4l2-subdev.h b/include/uapi/linux/v4l2-subdev.h
> index 45c01799e2cd..f20491e1f53f 100644
> --- a/include/uapi/linux/v4l2-subdev.h
> +++ b/include/uapi/linux/v4l2-subdev.h
> @@ -200,6 +200,13 @@ struct v4l2_subdev_capability {
>   */
>  #define V4L2_SUBDEV_ROUTE_FL_IMMUTABLE		BIT(1)
>  
> +/**
> + * Is the route a source endpoint? A source endpoint route doesn't come
> + * from "anywhere", and the sink_pad and sink_stream fields are unused.
> + * Set by the driver.
> + */
> +#define V4L2_SUBDEV_ROUTE_FL_SOURCE		BIT(2)
> +
>  /**
>   * struct v4l2_subdev_route - A route inside a subdev
>   *

-- 
Regards,

Laurent Pinchart