Re: [PATCH] staging: media: imx: ic-prp: add FORMAT_TRY frame interval support

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential
issue to consider:
- [Medium] staging: media: imx: ic-prp: inconsistent TRY vs ACTIVE pad
  frame intervals
--

commit ea3f743cedd8910d8654eb2253132f006f78cf9d
Author: Vickram Kapoor <vickramk.207@gmail.com>

staging: media: imx: ic-prp: add FORMAT_TRY frame interval support

This commit adds V4L2_SUBDEV_FORMAT_TRY frame interval support to the i.MX
IC pre-process router subdev by storing and retrieving per-pad intervals in
v4l2_subdev_state and initializing them in a custom init_state callback.

Link: https://lore.kernel.org/all/20260426002659.119625-1-vickramk.207@gmail.com/

> diff --git a/drivers/staging/media/imx/imx-ic-prp.c b/drivers/staging/media/imx/imx-ic-prp.c
> index b2c648149964c..3f1690d22483e 100644
> --- a/drivers/staging/media/imx/imx-ic-prp.c
> +++ b/drivers/staging/media/imx/imx-ic-prp.c
> @@ -87,6 +87,18 @@ __prp_get_fmt(struct prp_priv *priv, struct v4l2_subdev_state *sd_state,
>  		return &priv->format_mbus;
>  }
>  
> +static struct v4l2_fract *
> +__prp_get_frame_interval(struct prp_priv *priv,
> +			 struct v4l2_subdev_state *sd_state,
> +			 unsigned int pad,
> +			 enum v4l2_subdev_format_whence which)
> +{
> +	if (which == V4L2_SUBDEV_FORMAT_TRY)
> +		return v4l2_subdev_state_get_interval(sd_state, pad);
> +
> +	return &priv->frame_interval;
> +}

[ ... ]

> @@ -421,24 +436,50 @@ static int prp_set_frame_interval(struct v4l2_subdev *sd,
>  				  struct v4l2_subdev_frame_interval *fi)
>  {
>  	struct prp_priv *priv = sd_to_priv(sd);
> -
> -	/*
> -	 * FIXME: Implement support for V4L2_SUBDEV_FORMAT_TRY, using the V4L2
> -	 * subdev active state API.
> -	 */
> -	if (fi->which != V4L2_SUBDEV_FORMAT_ACTIVE)
> -		return -EINVAL;
> +	struct v4l2_fract *interval;
> +	int ret = 0;
>  
>  	if (fi->pad >= PRP_NUM_PADS)
>  		return -EINVAL;
>  
>  	mutex_lock(&priv->lock);
> +	interval = __prp_get_frame_interval(priv, sd_state, fi->pad,
> +					    fi->which);
> +	if (!interval) {
> +		ret = -EINVAL;
> +		goto out;
> +	}
>  
>  	/* No limits on valid frame intervals */
>  	if (fi->interval.numerator == 0 || fi->interval.denominator == 0)
> -		fi->interval = priv->frame_interval;
> +		fi->interval = *interval;
>  	else
> -		priv->frame_interval = fi->interval;
> +		*interval = fi->interval;
> +out:
>  	mutex_unlock(&priv->lock);
>  
> -	return 0;
> +	return ret;
> +}

[Severity: Medium]
Should prp_set_frame_interval() keep the source pad frame intervals in sync
with PRP_SINK_PAD for V4L2_SUBDEV_FORMAT_TRY?

The IC pre-process router does not perform frame rate conversion, and
__prp_get_frame_interval() returns the single shared &priv->frame_interval
for all pads when fi->which is V4L2_SUBDEV_FORMAT_ACTIVE.  For
V4L2_SUBDEV_FORMAT_TRY, however, v4l2_subdev_state_get_interval() returns a
separate struct v4l2_fract per pad.  Setting a TRY interval on PRP_SINK_PAD
leaves PRP_SRC_PAD_PRPENC and PRP_SRC_PAD_PRPVF with stale TRY intervals,
and calling VIDIOC_SUBDEV_S_FRAME_INTERVAL on a source pad allows setting an
independent TRY interval that cannot exist in V4L2_SUBDEV_FORMAT_ACTIVE,
unlike prp_set_fmt():

drivers/staging/media/imx/imx-ic-prp.c:prp_set_fmt() {
	...
	case PRP_SRC_PAD_PRPENC:
	case PRP_SRC_PAD_PRPVF:
		/* Output pads mirror input pad */
		sdformat->format = *infmt;
		break;
	...
}

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261107-batch1-m1-prp-try-v1-1-56a08f54791b@tubot.lat?part=1