Re: [PATCH v7 24/27] v4l: subdev: use streams in v4l2_subdev_link_validate()

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Tomi,

Thank you for the patch.

On Fri, May 28, 2021 at 02:34:55PM +0300, Tomi Valkeinen wrote:
> On 24/05/2021 13:44, Tomi Valkeinen wrote:
> > Update v4l2_subdev_link_validate() to use routing and streams for
> > validation.
> > 
> > Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
> > ---
> >   drivers/media/v4l2-core/v4l2-subdev.c | 184 +++++++++++++++++++++++---
> >   1 file changed, 166 insertions(+), 18 deletions(-)
> > 
> > diff --git a/drivers/media/v4l2-core/v4l2-subdev.c b/drivers/media/v4l2-core/v4l2-subdev.c
> > index da6ea9b14631..b30b456d8d99 100644
> > --- a/drivers/media/v4l2-core/v4l2-subdev.c
> > +++ b/drivers/media/v4l2-core/v4l2-subdev.c
> > @@ -16,6 +16,7 @@
> >   #include <linux/videodev2.h>
> >   #include <linux/export.h>
> >   #include <linux/version.h>
> > +#include <linux/sort.h>
> >   
> >   #include <media/v4l2-ctrls.h>
> >   #include <media/v4l2-device.h>
> > @@ -894,6 +895,7 @@ EXPORT_SYMBOL_GPL(v4l2_subdev_link_validate_default);
> >   
> >   static int
> >   v4l2_subdev_link_validate_get_format(struct media_pad *pad,
> > +				     u32 stream,
> >   				     struct v4l2_subdev_format *fmt)
> >   {
> >   	if (is_media_entity_v4l2_subdev(pad->entity)) {
> > @@ -902,6 +904,7 @@ v4l2_subdev_link_validate_get_format(struct media_pad *pad,
> >   
> >   		fmt->which = V4L2_SUBDEV_FORMAT_ACTIVE;
> >   		fmt->pad = pad->index;
> > +		fmt->stream = stream;
> >   		return v4l2_subdev_call(sd, pad, get_fmt, NULL, fmt);
> >   	}
> >   
> > @@ -1012,31 +1015,176 @@ bool v4l2_subdev_has_route(struct v4l2_subdev_krouting *routing,
> >   }
> >   EXPORT_SYMBOL_GPL(v4l2_subdev_has_route);
> >   
> > +static int cmp_u32(const void *a, const void *b)
> > +{
> > +	u32 a32 = *(u32 *)a;
> > +	u32 b32 = *(u32 *)b;
> > +
> > +	return a32 > b32 ? 1 : (a32 < b32 ? -1 : 0);
> > +}
> > +
> >   int v4l2_subdev_link_validate(struct media_link *link)
> >   {
> > -	struct v4l2_subdev *sink;
> > -	struct v4l2_subdev_format sink_fmt, source_fmt;
> > -	int rval;
> > +	int ret;
> > +	unsigned int i;
> >   

No need for a blank line, and I'd move i and ret (in that order) after
the variables below.

> > -	rval = v4l2_subdev_link_validate_get_format(
> > -		link->source, &source_fmt);
> > -	if (rval < 0)
> > -		return 0;
> > +	struct v4l2_subdev *source_subdev =
> > +		media_entity_to_v4l2_subdev(link->source->entity);
> > +	struct v4l2_subdev *sink_subdev =
> > +		media_entity_to_v4l2_subdev(link->sink->entity);
> > +	struct device *dev = sink_subdev->entity.graph_obj.mdev->dev;
> >   

No need for a blank line here either.

> > -	rval = v4l2_subdev_link_validate_get_format(
> > -		link->sink, &sink_fmt);
> > -	if (rval < 0)
> > -		return 0;
> > +	struct v4l2_subdev_krouting routing;
> >   

Same.

> > -	sink = media_entity_to_v4l2_subdev(link->sink->entity);
> > +	static const u32 default_streams[] = { 0 };

I'd move this one at the top.

> >   
> > -	rval = v4l2_subdev_call(sink, pad, link_validate, link,
> > -				&source_fmt, &sink_fmt);
> > -	if (rval != -ENOIOCTLCMD)
> > -		return rval;
> > +	u32 num_source_streams = 0;
> > +	const u32 *source_streams;
> > +	u32 num_sink_streams = 0;
> > +	const u32 *sink_streams;
> > +
> > +	dev_dbg(dev, "validating link \"%s\":%u -> \"%s\":%u\n",
> > +		link->source->entity->name, link->source->index,
> > +		link->sink->entity->name, link->sink->index);
> > +
> > +	/* Get source streams */
> > +
> > +	memset(&routing, 0, sizeof(routing));
> > +
> > +	ret = v4l2_subdev_get_routing(source_subdev, NULL, &routing);
> > +
> > +	if (ret && ret != -ENOIOCTLCMD)
> > +		return ret;
> > +
> > +	if (ret == -ENOIOCTLCMD) {
> > +		num_source_streams = 1;
> > +		source_streams = default_streams;
> > +	} else {
> > +		u32 *streams;
> > +
> > +		streams = kmalloc_array(routing.num_routes, sizeof(u32),
> > +					GFP_KERNEL);
> > +
> > +		for (i = 0; i < routing.num_routes; ++i) {
> > +			struct v4l2_subdev_route *route = &routing.routes[i];
> > +
> > +			if (!(route->flags & V4L2_SUBDEV_ROUTE_FL_ACTIVE))
> > +				continue;
> > +
> > +			if (route->source_pad == link->source->index)
> > +				streams[num_source_streams++] =
> > +					route->source_stream;
> > +		}
> > +
> > +		sort(streams, num_source_streams, sizeof(u32), &cmp_u32, NULL);
> > +
> > +		source_streams = streams;
> > +
> > +		v4l2_subdev_free_routing(&routing);
> > +	}

Could this be moved to a separate function ? The code below is very
similar.

> > +
> > +	/* Get sink streams */
> > +
> > +	memset(&routing, 0, sizeof(routing));
> > +
> > +	ret = v4l2_subdev_get_routing(sink_subdev, NULL, &routing);
> > +
> > +	if (ret && ret != -ENOIOCTLCMD)
> > +		return ret;
> > +
> > +	if (ret == -ENOIOCTLCMD) {
> > +		num_sink_streams = 1;
> > +		sink_streams = default_streams;
> > +	} else {
> > +		u32 *streams;
> >   
> > -	return v4l2_subdev_link_validate_default(
> > -		sink, link, &source_fmt, &sink_fmt);
> > +		streams = kmalloc_array(routing.num_routes, sizeof(u32),
> > +					GFP_KERNEL);
> > +
> > +		for (i = 0; i < routing.num_routes; ++i) {
> > +			struct v4l2_subdev_route *route = &routing.routes[i];
> > +
> > +			if (!(route->flags & V4L2_SUBDEV_ROUTE_FL_ACTIVE))
> > +				continue;
> > +
> > +			if (route->sink_pad == link->sink->index)
> > +				streams[num_sink_streams++] =
> > +					route->sink_stream;
> > +		}
> > +
> > +		sort(streams, num_sink_streams, sizeof(u32), &cmp_u32, NULL);

Are you aware that there can be duplicate in the streams array, as a
given stream on a sink pad can be routed to multiple source pads ? I
think that will fail the sink and source streams match test below.

> > +
> > +		sink_streams = streams;
> > +
> > +		v4l2_subdev_free_routing(&routing);
> > +	}
> > +
> > +	if (num_source_streams != num_sink_streams) {
> > +		dev_err(dev,
> > +			"Sink and source stream count mismatch: %d vs %d\n",
> > +			num_source_streams, num_sink_streams);
> > +		return -EINVAL;
> > +	}
> > +
> > +	/* Validate source and sink stream formats */
> > +
> > +	for (i = 0; i < num_source_streams; ++i) {
> > +		struct v4l2_subdev_format sink_fmt, source_fmt;
> > +		u32 stream;
> > +		int ret;
> > +
> > +		if (source_streams[i] != sink_streams[i]) {
> > +			dev_err(dev, "Sink and source streams do not match\n");
> > +			return -EINVAL;
> > +		}

What if the source subdev as a route enabled that produces a stream, and
the sink subdev has not corresponding enabled route ? Isn't this a valid
configuration ? For instance, when a CSI-2 sensor produces image data
and embedded data in two streams with different CSI-2 DT, the embedded
data doesn't have to be captured, it could be dropped in the CSI-2
receiver.

> > +
> > +		stream = source_streams[i];
> > +
> > +		dev_dbg(dev, "validating stream \"%s\":%u:%u -> \"%s\":%u:%u\n",
> > +			link->source->entity->name, link->source->index, stream,
> > +			link->sink->entity->name, link->sink->index, stream);
> > +
> > +		ret = v4l2_subdev_link_validate_get_format(link->source, stream,
> > +							   &source_fmt);
> > +		if (ret < 0) {
> > +			dev_err(dev, "Failed to get format for \"%s\":%u:%u\n",
> > +				link->source->entity->name, link->source->index,
> > +				stream);
> > +			return ret;
> > +		}
> > +
> > +		ret = v4l2_subdev_link_validate_get_format(link->sink, stream,
> > +							   &sink_fmt);
> > +		if (ret < 0) {
> > +			dev_err(dev, "Failed to get format for \"%s\":%u:%u\n",
> > +				link->sink->entity->name, link->sink->index,
> > +				stream);
> > +			return ret;
> > +		}
> > +
> > +		/* TODO: add stream number to link_validate() */
> > +		ret = v4l2_subdev_call(sink_subdev, pad, link_validate, link,
> > +				       &source_fmt, &sink_fmt);
> > +		if (!ret)
> > +			continue;
> > +
> > +		if (ret != -ENOIOCTLCMD)
> > +			return ret;
> > +
> > +		ret = v4l2_subdev_link_validate_default(sink_subdev, link,
> > +							&source_fmt, &sink_fmt);
> > +
> > +		if (ret)
> > +			return ret;
> > +	}
> > +
> > +	if (source_streams != default_streams)
> > +		kfree(source_streams);
> > +
> > +	if (sink_streams != default_streams)
> > +		kfree(sink_streams);
> > +
> > +	return 0;
> >   }
> >   EXPORT_SYMBOL_GPL(v4l2_subdev_link_validate);
> >   
> 
> I noticed two issues with this patch:
> 
> - It leaks memory on error cases.
> 
> - The previous behavior silently ignored failures to get format from 
> subdevs, and returned 0. This one fails.
> 
> I'll fix those.

-- 
Regards,

Laurent Pinchart