Re: [PATCH v3 04/12] media: nxp: imx8-isi: Allow num_sources to be greater than num_sink

[Frank Li]

On Thu, Mar 27, 2025 at 03:02:29PM -0500, Adam Ford wrote:
> On Mon, Feb 10, 2025 at 3:01 PM Frank Li <Frank.Li@xxxxxxx> wrote:
> >
> > Allow num_sources (drvdata: num_channels) to be greater than num_sink
> > (drvdata: num_ports + 1).
> >
> > ISI support stream multiplexing, such as differentiates multiple cameras
> > from a single 2-lane MIPI input, or duplicates input stream into multiple
> > outputs. So num_channels may be greater than num_ports at some platform.
>
> Can you tell me which platforms support this?

iMX8QM.

>  Is this through
> virtual channels, or do you physically connect lanes 1 and 2 to one
> camera and lanes 3 and 4 to another?

Not like that.  for example, camera 0 as input0

channels 0 can covert input0 to RGB format to memory 1
channels 1 can scale down input0 to to memory 2

I think it most likely use for channel0 to preview image, channel1 to save
input to file on storage.

Frank
>
> adam
> >
> > Signed-off-by: Frank Li <Frank.Li@xxxxxxx>
> > ---
> > change from v1 to v3
> > - none
> > ---
> >  drivers/media/platform/nxp/imx8-isi/imx8-isi-crossbar.c | 8 ++++----
> >  1 file changed, 4 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/media/platform/nxp/imx8-isi/imx8-isi-crossbar.c b/drivers/media/platform/nxp/imx8-isi/imx8-isi-crossbar.c
> > index 93a55c97cd173..ba5b2d3617a23 100644
> > --- a/drivers/media/platform/nxp/imx8-isi/imx8-isi-crossbar.c
> > +++ b/drivers/media/platform/nxp/imx8-isi/imx8-isi-crossbar.c
> > @@ -188,11 +188,11 @@ static int mxc_isi_crossbar_init_state(struct v4l2_subdev *sd,
> >          * Create a 1:1 mapping between pixel link inputs and outputs to
> >          * pipelines by default.
> >          */
> > -       routes = kcalloc(xbar->num_sources, sizeof(*routes), GFP_KERNEL);
> > +       routes = kcalloc(xbar->num_sinks - 1, sizeof(*routes), GFP_KERNEL);
> >         if (!routes)
> >                 return -ENOMEM;
> >
> > -       for (i = 0; i < xbar->num_sources; ++i) {
> > +       for (i = 0; i < xbar->num_sinks - 1; ++i) {
> >                 struct v4l2_subdev_route *route = &routes[i];
> >
> >                 route->sink_pad = i;
> > @@ -200,7 +200,7 @@ static int mxc_isi_crossbar_init_state(struct v4l2_subdev *sd,
> >                 route->flags = V4L2_SUBDEV_ROUTE_FL_ACTIVE;
> >         }
> >
> > -       routing.num_routes = xbar->num_sources;
> > +       routing.num_routes = xbar->num_sinks - 1;
> >         routing.routes = routes;
> >
> >         ret = __mxc_isi_crossbar_set_routing(sd, state, &routing);
> > @@ -453,7 +453,7 @@ int mxc_isi_crossbar_init(struct mxc_isi_dev *isi)
> >          * the memory input.
> >          */
> >         xbar->num_sinks = isi->pdata->num_ports + 1;
> > -       xbar->num_sources = isi->pdata->num_ports;
> > +       xbar->num_sources = isi->pdata->num_channels;
> >         num_pads = xbar->num_sinks + xbar->num_sources;
> >
> >         xbar->pads = kcalloc(num_pads, sizeof(*xbar->pads), GFP_KERNEL);
> >
> > --
> > 2.34.1
> >
> >