Re: [PATCH v4 5/9] media: rcar-vin: Parse parallel input on Gen3

[jacopo mondi <jacopo@jmondi.org>]

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Hi Niklas,
   I might have another question before sending v5.

On Fri, May 25, 2018 at 12:29:44AM +0200, Niklas Söderlund wrote:
> Hi Jacopo,
>
> Thanks for your work.
>
> I really like what you did with this patch in v4.
>
> On 2018-05-25 00:02:15 +0200, Jacopo Mondi wrote:
> > The rcar-vin driver so far had a mutually exclusive code path for
> > handling parallel and CSI-2 video input subdevices, with only the CSI-2
> > use case supporting media-controller. As we add support for parallel
> > inputs to Gen3 media-controller compliant code path now parse both port@0
> > and port@1, handling the media-controller use case in the parallel
> > bound/unbind notifier operations.
> >
> > Signed-off-by: Jacopo Mondi <jacopo+renesas@jmondi.org>
> >
> > ---
> > v3 -> v4:
> > - Change the mc/parallel initialization order. Initialize mc first, then
> >   parallel
> > - As a consequence no need to delay parallel notifiers registration, the
> >   media controller is set up already when parallel input got parsed,
> >   this greatly simplify the group notifier complete callback.
> > ---
> >  drivers/media/platform/rcar-vin/rcar-core.c | 56 ++++++++++++++++++-----------
> >  1 file changed, 35 insertions(+), 21 deletions(-)
> >
> > diff --git a/drivers/media/platform/rcar-vin/rcar-core.c b/drivers/media/platform/rcar-vin/rcar-core.c
> > index a799684..29619c2 100644
> > --- a/drivers/media/platform/rcar-vin/rcar-core.c
> > +++ b/drivers/media/platform/rcar-vin/rcar-core.c
> > @@ -399,6 +399,11 @@ static int rvin_parallel_subdevice_attach(struct rvin_dev *vin,
> >  	ret = rvin_find_pad(subdev, MEDIA_PAD_FL_SINK);
> >  	vin->parallel->sink_pad = ret < 0 ? 0 : ret;
> >
> > +	if (vin->info->use_mc) {
> > +		vin->parallel->subdev = subdev;
> > +		return 0;
> > +	}
> > +
> >  	/* Find compatible subdevices mbus format */
> >  	vin->mbus_code = 0;
> >  	code.index = 0;
> > @@ -460,10 +465,12 @@ static int rvin_parallel_subdevice_attach(struct rvin_dev *vin,
> >  static void rvin_parallel_subdevice_detach(struct rvin_dev *vin)
> >  {
> >  	rvin_v4l2_unregister(vin);
> > -	v4l2_ctrl_handler_free(&vin->ctrl_handler);
> > -
> > -	vin->vdev.ctrl_handler = NULL;
> >  	vin->parallel->subdev = NULL;
> > +
> > +	if (!vin->info->use_mc) {
> > +		v4l2_ctrl_handler_free(&vin->ctrl_handler);
> > +		vin->vdev.ctrl_handler = NULL;
> > +	}
> >  }
> >
> >  static int rvin_parallel_notify_complete(struct v4l2_async_notifier *notifier)
> > @@ -552,18 +559,18 @@ static int rvin_parallel_parse_v4l2(struct device *dev,
> >  	return 0;
> >  }
> >
> > -static int rvin_parallel_graph_init(struct rvin_dev *vin)
> > +static int rvin_parallel_init(struct rvin_dev *vin)
> >  {
> >  	int ret;
> >
> > -	ret = v4l2_async_notifier_parse_fwnode_endpoints(
> > -		vin->dev, &vin->notifier,
> > -		sizeof(struct rvin_parallel_entity), rvin_parallel_parse_v4l2);
> > +	ret = v4l2_async_notifier_parse_fwnode_endpoints_by_port(
> > +		vin->dev, &vin->notifier, sizeof(struct rvin_parallel_entity),
> > +		0, rvin_parallel_parse_v4l2);
> >  	if (ret)
> >  		return ret;
> >
> >  	if (!vin->parallel)
> > -		return -ENODEV;
> > +		return -ENOTCONN;
>
> I think you still should return -ENODEV here if !vin->info->use_mc to
> preserve Gen2 which runs without media controller behavior. How about:
>
>     return vin->info->use_mc ? -ENOTCONN : -ENODEV;
>
> >
> >  	vin_dbg(vin, "Found parallel subdevice %pOF\n",
> >  		to_of_node(vin->parallel->asd.match.fwnode));
> > @@ -784,14 +791,8 @@ static int rvin_mc_init(struct rvin_dev *vin)
> >  {
> >  	int ret;
> >
> > -	vin->pad.flags = MEDIA_PAD_FL_SINK;
> > -	ret = media_entity_pads_init(&vin->vdev.entity, 1, &vin->pad);
> > -	if (ret)
> > -		return ret;
> > -
> > -	ret = rvin_group_get(vin);
> > -	if (ret)
> > -		return ret;
> > +	if (!vin->info->use_mc)
> > +		return 0;
> >
> >  	ret = rvin_mc_parse_of_graph(vin);
> >  	if (ret)
> > @@ -1074,11 +1075,24 @@ static int rcar_vin_probe(struct platform_device *pdev)
> >  		return ret;
> >
> >  	platform_set_drvdata(pdev, vin);
> > -	if (vin->info->use_mc)
> > -		ret = rvin_mc_init(vin);
> > -	else
> > -		ret = rvin_parallel_graph_init(vin);
> > -	if (ret < 0)
> > +
> > +	if (vin->info->use_mc) {
> > +		vin->pad.flags = MEDIA_PAD_FL_SINK;
> > +		ret = media_entity_pads_init(&vin->vdev.entity, 1, &vin->pad);
> > +		if (ret)
> > +			return ret;
> > +
> > +		ret = rvin_group_get(vin);
> > +		if (ret)
> > +			return ret;
> > +	}
>
> I don't see why you need to move the media pad creation out of
> rvin_mc_init(). With the reorder of the rvin_mc_init()
> rvin_parallel_init() I would keep this in rvin_mc_init().
>
> > +
> > +	ret = rvin_mc_init(vin);
> > +	if (ret)
> > +		return ret;
> > +
> > +	ret = rvin_parallel_init(vin);
> > +	if (ret < 0 && ret != -ENOTCONN)
> >  		goto error;
> >
> >  	pm_suspend_ignore_children(&pdev->dev, true);

I've been looking at the error path handling now that the code looks
like this in the forthcoming v5:

	if (vin->info->use_mc) {
		ret = rvin_mc_init(vin);
		if (ret)
			goto error_dma_unregister;
	}

	ret = rvin_parallel_init(vin);
	if (ret)
		goto error_group_unregister;


        ...


error_group_unreg:
	if (vin->info->use_mc) {
		mutex_lock(&vin->group->lock);
		if (&vin->v4l2_dev == vin->group->notifier.v4l2_dev) {
			v4l2_async_notifier_unregister(&vin->group->notifier);
			v4l2_async_notifier_cleanup(&vin->group->notifier);
		}
		mutex_unlock(&vin->group->lock);
		rvin_group_put(vin);
	}

error_dma_unreg:
	rvin_dma_unregister(vin);

	return ret;

Question is, do you think the group notifier should be unregistered
and cleaned up if the parallel input initialization of the VIN
instance whose v4l2_dev is used to register the group notifier fails?

I feel like it should, as the VIN instance whose v4l2_dev is used is
always the last probing one, so there should be no issues with other
VINs registering after it and finding themselves without a valid
notifier.

I felt like it was better anticipating this to you instead of adding
this part out of the blue in v5.

Also, I think in both parallel input and mc notifier registration, the
notifier should be cleaned up to release the parsed async subdevices
memory allocated by
v4l2_async_notifier_parse_fwnode_endpoints_by_port() if the
sub-sequent v4l2_async_notifier_register() fails.

That would be:

@@ -781,18 +782,29 @@ static int rvin_mc_parse_of_graph(struct rvin_dev *vin)
                                           &vin->group->notifier);
        if (ret < 0) {
                vin_err(vin, "Notifier registration failed\n");
-               return ret;
+               goto error_clean_up_notifier;
        }

        return 0;
+
+error_clean_up_notifier:
+       v4l2_async_notifier_cleanup(&vin->group->notifier);
+
+       return ret;
 }

in both mc and parallel initialization functions.

With your ack I can send two patches on top of the currently merged VIN
version, and rebase my series on top eventually.

Sorry for the long email.

Thanks
   j


> > --
> > 2.7.4
> >
>
> --
> Regards,
> Niklas Söderlund

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