Re: [PATCH v12 09/17] media: cadence: csi2rx: add get_frame_desc wrapper

[Sakari Ailus]

Hi Rishikesh,

On Wed, May 20, 2026 at 12:14:34PM +0530, Rishikesh Donadkar wrote:
> 
> On 19/05/26 17:26, Sakari Ailus wrote:
> > Hi Rishikesh,
> 
> 
> Hi Sakari,
> 
> Thank you for the review !
> 
> > 
> > On Fri, Mar 13, 2026 at 02:36:53PM +0530, Rishikesh Donadkar wrote:
> > > From: Pratyush Yadav <p.yadav@xxxxxx>
> > > 
> > > J721E wrapper CSI2RX driver needs to get the frame descriptor from the
> > > source to find out info about virtual channel. This driver itself does
> > > not touch the routing or virtual channels in any way. So simply pass the
> > > descriptor through from the source.
> > > 
> > > Signed-off-by: Pratyush Yadav <p.yadav@xxxxxx>
> > > Signed-off-by: Jai Luthra <j-luthra@xxxxxx>
> > > Reviewed-by: Jacopo Mondi <jacopo.mondi@xxxxxxxxxxxxxxxx>
> > > Reviewed-by: Changhuang Liang <changhuang.liang@xxxxxxxxxxxxxxxx>
> > > Reviewed-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
> > > Reviewed-by: Yemike Abhilash Chandra <y-abhilashchandra@xxxxxx>
> > > Reviewed-by: Tomi Valkeinen <tomi.valkeinen@xxxxxxxxxxxxxxxx>
> > > Signed-off-by: Rishikesh Donadkar <r-donadkar@xxxxxx>
> > > ---
> > >   drivers/media/platform/cadence/cdns-csi2rx.c | 24 ++++++++++++++++++++
> > >   1 file changed, 24 insertions(+)
> > > 
> > > diff --git a/drivers/media/platform/cadence/cdns-csi2rx.c b/drivers/media/platform/cadence/cdns-csi2rx.c
> > > index 2b25314ba6ab0..52ca940acd7d0 100644
> > > --- a/drivers/media/platform/cadence/cdns-csi2rx.c
> > > +++ b/drivers/media/platform/cadence/cdns-csi2rx.c
> > > @@ -229,6 +229,21 @@ static const struct csi2rx_fmt *csi2rx_get_fmt_by_code(u32 code)
> > >   	return NULL;
> > >   }
> > > +static int csi2rx_get_frame_desc_from_source(struct csi2rx_priv *csi2rx,
> > > +					     struct v4l2_mbus_frame_desc *fd)
> > > +{
> > > +	struct media_pad *remote_pad;
> > > +
> > > +	remote_pad = media_entity_remote_source_pad_unique(&csi2rx->subdev.entity);
> > > +	if (!remote_pad) {
> > media_entity_remote_source_pad_unique() returns an error code on error,
> > never NULL.
> 
> 
> Will fix the error handling
> 
> 
> > 
> > Could you use you use v4l2_subdev_get_frame_desc_passthrough()
> 
> 
> Yes, v4l2_subdev_get_frame_desc_passthrough() can be directly used as
> .get_frame_desc helper, but will need the
> csi2rx_get_frame_desc_from_source() in ([PATCH 11/17] media: cadence:
> csi2rx: add multistream support) as we used the VCs in the fd to configure
> the IP.
> 
> 
> So, I will drop this patch and add csi2rx_get_frame_desc_from_source() with
> improved error handling in PATCH 11/17

It's fine as-is if you switch to v4l2_subdev_get_frame_desc_passthrough()
later on in the set (but please still fix error handling).

> 
> 
> Rishikesh
> 
> > 
> > > +		dev_err(csi2rx->dev, "No remote pad found for sink\n");
> > > +		return -ENODEV;
> > > +	}
> > > +
> > > +	return v4l2_subdev_call(csi2rx->source_subdev, pad, get_frame_desc,
> > > +				remote_pad->index, fd);
> > > +}
> > > +
> > >   static inline
> > >   struct csi2rx_priv *v4l2_subdev_to_csi2rx(struct v4l2_subdev *subdev)
> > >   {
> > > @@ -611,12 +626,21 @@ int cdns_csi2rx_negotiate_ppc(struct v4l2_subdev *subdev, unsigned int pad,
> > >   }
> > >   EXPORT_SYMBOL_FOR_MODULES(cdns_csi2rx_negotiate_ppc, "j721e-csi2rx");
> > > +static int csi2rx_get_frame_desc(struct v4l2_subdev *subdev, unsigned int pad,
> > > +				 struct v4l2_mbus_frame_desc *fd)
> > > +{
> > > +	struct csi2rx_priv *csi2rx = v4l2_subdev_to_csi2rx(subdev);
> > > +
> > > +	return csi2rx_get_frame_desc_from_source(csi2rx, fd);
> > > +}
> > > +
> > >   static const struct v4l2_subdev_pad_ops csi2rx_pad_ops = {
> > >   	.enum_mbus_code	= csi2rx_enum_mbus_code,
> > >   	.get_fmt	= v4l2_subdev_get_fmt,
> > >   	.set_fmt	= csi2rx_set_fmt,
> > >   	.enable_streams         = csi2rx_enable_streams,
> > >   	.disable_streams        = csi2rx_disable_streams,
> > > +	.get_frame_desc	= csi2rx_get_frame_desc,
> > >   };
> > >   static const struct v4l2_subdev_core_ops csi2rx_core_ops = {

-- 
Regards,

Sakari Ailus