Re: [PATCH v3 26/31] adv748x: csi2: add internal routing configuration

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Hi,

begging your pardon for the noob question below...

On 05/03/19 19:51, Jacopo Mondi wrote:
> From: Niklas Söderlund <niklas.soderlund+renesas@xxxxxxxxxxxx>
> 
> Add support to get and set the internal routing between the adv748x
> CSI-2 transmitters sink pad and its multiplexed source pad. This routing
> includes which stream of the multiplexed pad to use, allowing the user
> to select which CSI-2 virtual channel to use when transmitting the
> stream.
> 
> Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@xxxxxxxxxxxx>
> Reviewed-by: Jacopo Mondi <jacopo+renesas@xxxxxxxxxx>
> ---
>  drivers/media/i2c/adv748x/adv748x-csi2.c | 65 ++++++++++++++++++++++++
>  1 file changed, 65 insertions(+)
> 
> diff --git a/drivers/media/i2c/adv748x/adv748x-csi2.c b/drivers/media/i2c/adv748x/adv748x-csi2.c
> index d8f7cbee86e7..13454af72c6e 100644
> --- a/drivers/media/i2c/adv748x/adv748x-csi2.c
> +++ b/drivers/media/i2c/adv748x/adv748x-csi2.c
> @@ -14,6 +14,8 @@
>  
>  #include "adv748x.h"
>  
> +#define ADV748X_CSI2_ROUTES_MAX 4
> +
>  struct adv748x_csi2_format {
>  	unsigned int code;
>  	unsigned int datatype;
> @@ -253,10 +255,73 @@ static int adv748x_csi2_get_frame_desc(struct v4l2_subdev *sd, unsigned int pad,
>  	return 0;
>  }
>  
> +static int adv748x_csi2_get_routing(struct v4l2_subdev *sd,
> +				    struct v4l2_subdev_krouting *routing)
> +{
> +	struct adv748x_csi2 *tx = adv748x_sd_to_csi2(sd);
> +	struct v4l2_subdev_route *r = routing->routes;
> +	unsigned int vc;
> +
> +	if (routing->num_routes < ADV748X_CSI2_ROUTES_MAX) {
> +		routing->num_routes = ADV748X_CSI2_ROUTES_MAX;
> +		return -ENOSPC;
> +	}
> +
> +	routing->num_routes = ADV748X_CSI2_ROUTES_MAX;
> +
> +	for (vc = 0; vc < ADV748X_CSI2_ROUTES_MAX; vc++) {
> +		r->sink_pad = ADV748X_CSI2_SINK;
> +		r->sink_stream = 0;
> +		r->source_pad = ADV748X_CSI2_SOURCE;
> +		r->source_stream = vc;
> +		r->flags = vc == tx->vc ? V4L2_SUBDEV_ROUTE_FL_ACTIVE : 0;
> +		r++;Begging your pardon for the noob question...

> +	}
> +
> +	return 0;
> +}
> +
> +static int adv748x_csi2_set_routing(struct v4l2_subdev *sd,
> +				    struct v4l2_subdev_krouting *routing)
> +{
> +	struct adv748x_csi2 *tx = adv748x_sd_to_csi2(sd);
> +	struct v4l2_subdev_route *r = routing->routes;
> +	unsigned int i;
> +	int vc = -1;
> +
> +	if (routing->num_routes > ADV748X_CSI2_ROUTES_MAX)
> +		return -ENOSPC;
> +
> +	for (i = 0; i < routing->num_routes; i++) {
> +		if (r->sink_pad != ADV748X_CSI2_SINK ||
> +		    r->sink_stream != 0 ||
> +		    r->source_pad != ADV748X_CSI2_SOURCE ||
> +		    r->source_stream >= ADV748X_CSI2_ROUTES_MAX)
> +			return -EINVAL;
> +
> +		if (r->flags & V4L2_SUBDEV_ROUTE_FL_ACTIVE) {
> +			if (vc != -1)
> +				return -EMLINK;
> +
> +			vc = r->source_stream;
> +		}
> +		r++;
> +	}
> +
> +	if (vc != -1)
> +		tx->vc = vc;
> +
> +	adv748x_csi2_set_virtual_channel(tx, tx->vc);
> +
> +	return 0;
> +}

Not specific to this patch but rather to the set_routing idea as a
whole: can the set_routing ioctl be called while the stream is running?

If it cannot, I find it a limiting factor for nowadays use cases. I also
didn't find where the ioctl is rejected.

If it can, then shouldn't this function call s_stream(stop) through the
sink pad whose route becomes disabled, and a s_stream(start) through the
one that gets enabled?

Thanks,
-- 
Luca



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