Re: [PATCH v2 38/55] media: rkisp1: isp: Disallow multiple active sources

[paul.elder@ideasonboard.com]

Hi Laurent,

On Fri, Jul 01, 2022 at 02:06:56AM +0300, Laurent Pinchart wrote:
> The ISP supports multiple source subdevs, but can only capture from a
> single one at a time. The source is selected through link setup. The
> driver finds the active source in its .s_stream() handler using the
> media_entity_remote_pad() function. This fails to reject invalid
> configurations with multiple active sources. Fix it by using the
> media_entity_remote_source_pad() helper instead, and inline
> rkisp1_isp_get_source() in rkisp1_isp_s_stream() as the function is
> small and has a single caller.
> 
> Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

Reviewed-by: Paul Elder <paul.elder@ideasonboard.com>

> ---
>  .../platform/rockchip/rkisp1/rkisp1-isp.c     | 30 ++++++++-----------
>  1 file changed, 13 insertions(+), 17 deletions(-)
> 
> diff --git a/drivers/media/platform/rockchip/rkisp1/rkisp1-isp.c b/drivers/media/platform/rockchip/rkisp1/rkisp1-isp.c
> index 37623b73b1d9..d7e2802d11f5 100644
> --- a/drivers/media/platform/rockchip/rkisp1/rkisp1-isp.c
> +++ b/drivers/media/platform/rockchip/rkisp1/rkisp1-isp.c
> @@ -58,20 +58,6 @@
>   * Helpers
>   */
>  
> -static struct v4l2_subdev *rkisp1_isp_get_source(struct v4l2_subdev *sd)
> -{
> -	struct media_pad *local, *remote;
> -	struct media_entity *sensor_me;
> -
> -	local = &sd->entity.pads[RKISP1_ISP_PAD_SINK_VIDEO];
> -	remote = media_pad_remote_pad_first(local);
> -	if (!remote)
> -		return NULL;
> -
> -	sensor_me = remote->entity;
> -	return media_entity_to_v4l2_subdev(sensor_me);
> -}
> -
>  static struct v4l2_mbus_framefmt *
>  rkisp1_isp_get_pad_fmt(struct rkisp1_isp *isp,
>  		       struct v4l2_subdev_state *sd_state,
> @@ -743,6 +729,8 @@ static int rkisp1_isp_s_stream(struct v4l2_subdev *sd, int enable)
>  	struct rkisp1_isp *isp = to_rkisp1_isp(sd);
>  	struct rkisp1_device *rkisp1 = isp->rkisp1;
>  	const struct rkisp1_sensor_async *asd;
> +	struct media_pad *source_pad;
> +	struct media_pad *sink_pad;
>  	int ret;
>  
>  	if (!enable) {
> @@ -754,10 +742,18 @@ static int rkisp1_isp_s_stream(struct v4l2_subdev *sd, int enable)
>  		return 0;
>  	}
>  
> -	rkisp1->source = rkisp1_isp_get_source(sd);
> +	sink_pad = &isp->pads[RKISP1_ISP_PAD_SINK_VIDEO];
> +	source_pad = media_pad_remote_pad_unique(sink_pad);
> +	if (IS_ERR(source_pad)) {
> +		dev_dbg(rkisp1->dev, "Failed to get source for ISP: %ld\n",
> +			PTR_ERR(source_pad));
> +		return -EPIPE;
> +	}
> +
> +	rkisp1->source = media_entity_to_v4l2_subdev(source_pad->entity);
>  	if (!rkisp1->source) {
> -		dev_warn(rkisp1->dev, "No link between isp and source\n");
> -		return -ENODEV;
> +		/* This should really not happen, so is not worth a message. */
> +		return -EPIPE;
>  	}
>  
>  	asd = container_of(rkisp1->source->asd, struct rkisp1_sensor_async,