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From: Laurent Pinchart <laurent.pinchart-ryLnwIuWjnjg/C1BVhZhaw@public.gmane.org>
To: Sakari Ailus <sakari.ailus-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
Cc: linux-media-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	niklas.soderlund-1zkq55x86MTxsAP9Fp7wbw@public.gmane.org,
	robh-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org,
	hverkuil-qWit8jRvyhVmR6Xm/wNWPw@public.gmane.org,
	devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: Re: [PATCH v5 4/5] v4l: fwnode: Support generic parsing of graph endpoints in a device
Date: Tue, 29 Aug 2017 17:02:54 +0300	[thread overview]
Message-ID: <2739432.dQ1BSg1MPy@avalon> (raw)
In-Reply-To: <20170829110313.19538-5-sakari.ailus-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>

Hi Sakari,

Thank you for the patch.

On Tuesday, 29 August 2017 14:03:12 EEST Sakari Ailus wrote:
> The current practice is that drivers iterate over their endpoints and
> parse each endpoint separately. This is very similar in a number of
> drivers, implement a generic function for the job. Driver specific matters
> can be taken into account in the driver specific callback.
> 
> Convert the omap3isp as an example.
> 
> Signed-off-by: Sakari Ailus <sakari.ailus-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
> ---
>  drivers/media/platform/omap3isp/isp.c | 115 ++++++++++-------------------
>  drivers/media/platform/omap3isp/isp.h |   5 +-
>  drivers/media/v4l2-core/v4l2-async.c  |  16 +++++
>  drivers/media/v4l2-core/v4l2-fwnode.c | 132
> ++++++++++++++++++++++++++++++++++ include/media/v4l2-async.h            | 
> 20 +++++-
>  include/media/v4l2-fwnode.h           |  39 ++++++++++
>  6 files changed, 242 insertions(+), 85 deletions(-)
> 
> diff --git a/drivers/media/platform/omap3isp/isp.c
> b/drivers/media/platform/omap3isp/isp.c index 1a428fe9f070..a546cf774d40
> 100644
> --- a/drivers/media/platform/omap3isp/isp.c
> +++ b/drivers/media/platform/omap3isp/isp.c
> @@ -2001,6 +2001,7 @@ static int isp_remove(struct platform_device *pdev)
>  	__omap3isp_put(isp, false);
> 
>  	media_entity_enum_cleanup(&isp->crashed);
> +	v4l2_async_notifier_release(&isp->notifier);
> 
>  	return 0;
>  }
> @@ -2011,44 +2012,41 @@ enum isp_of_phy {
>  	ISP_OF_PHY_CSIPHY2,
>  };
> 
> -static int isp_fwnode_parse(struct device *dev, struct fwnode_handle
> *fwnode, -			    struct isp_async_subdev *isd)
> +static int isp_fwnode_parse(struct device *dev,
> +			    struct v4l2_fwnode_endpoint *vep,
> +			    struct v4l2_async_subdev *asd)
>  {
> +	struct isp_async_subdev *isd =
> +		container_of(asd, struct isp_async_subdev, asd);
>  	struct isp_bus_cfg *buscfg = &isd->bus;
> -	struct v4l2_fwnode_endpoint vep;
> -	unsigned int i;
> -	int ret;
>  	bool csi1 = false;
> -
> -	ret = v4l2_fwnode_endpoint_parse(fwnode, &vep);
> -	if (ret)
> -		return ret;
> +	unsigned int i;
> 
>  	dev_dbg(dev, "parsing endpoint %pOF, interface %u\n",
> -		to_of_node(fwnode), vep.base.port);
> +		to_of_node(vep->base.local_fwnode), vep->base.port);
> 
> -	switch (vep.base.port) {
> +	switch (vep->base.port) {
>  	case ISP_OF_PHY_PARALLEL:
>  		buscfg->interface = ISP_INTERFACE_PARALLEL;
>  		buscfg->bus.parallel.data_lane_shift =
> -			vep.bus.parallel.data_shift;
> +			vep->bus.parallel.data_shift;
>  		buscfg->bus.parallel.clk_pol =
> -			!!(vep.bus.parallel.flags
> +			!!(vep->bus.parallel.flags
>  			   & V4L2_MBUS_PCLK_SAMPLE_FALLING);
>  		buscfg->bus.parallel.hs_pol =
> -			!!(vep.bus.parallel.flags & V4L2_MBUS_VSYNC_ACTIVE_LOW);
> +			!!(vep->bus.parallel.flags & V4L2_MBUS_VSYNC_ACTIVE_LOW);
>  		buscfg->bus.parallel.vs_pol =
> -			!!(vep.bus.parallel.flags & V4L2_MBUS_HSYNC_ACTIVE_LOW);
> +			!!(vep->bus.parallel.flags & V4L2_MBUS_HSYNC_ACTIVE_LOW);
>  		buscfg->bus.parallel.fld_pol =
> -			!!(vep.bus.parallel.flags & V4L2_MBUS_FIELD_EVEN_LOW);
> +			!!(vep->bus.parallel.flags & V4L2_MBUS_FIELD_EVEN_LOW);
>  		buscfg->bus.parallel.data_pol =
> -			!!(vep.bus.parallel.flags & V4L2_MBUS_DATA_ACTIVE_LOW);
> -		buscfg->bus.parallel.bt656 = vep.bus_type == V4L2_MBUS_BT656;
> +			!!(vep->bus.parallel.flags & V4L2_MBUS_DATA_ACTIVE_LOW);
> +		buscfg->bus.parallel.bt656 = vep->bus_type == V4L2_MBUS_BT656;
>  		break;
> 
>  	case ISP_OF_PHY_CSIPHY1:
>  	case ISP_OF_PHY_CSIPHY2:
> -		switch (vep.bus_type) {
> +		switch (vep->bus_type) {
>  		case V4L2_MBUS_CCP2:
>  		case V4L2_MBUS_CSI1:
>  			dev_dbg(dev, "CSI-1/CCP-2 configuration\n");
> @@ -2060,11 +2058,11 @@ static int isp_fwnode_parse(struct device *dev,
> struct fwnode_handle *fwnode, break;
>  		default:
>  			dev_err(dev, "unsupported bus type %u\n",
> -				vep.bus_type);
> +				vep->bus_type);
>  			return -EINVAL;
>  		}
> 
> -		switch (vep.base.port) {
> +		switch (vep->base.port) {
>  		case ISP_OF_PHY_CSIPHY1:
>  			if (csi1)
>  				buscfg->interface = ISP_INTERFACE_CCP2B_PHY1;
> @@ -2080,47 +2078,47 @@ static int isp_fwnode_parse(struct device *dev,
> struct fwnode_handle *fwnode, }
>  		if (csi1) {
>  			buscfg->bus.ccp2.lanecfg.clk.pos =
> -				vep.bus.mipi_csi1.clock_lane;
> +				vep->bus.mipi_csi1.clock_lane;
>  			buscfg->bus.ccp2.lanecfg.clk.pol =
> -				vep.bus.mipi_csi1.lane_polarity[0];
> +				vep->bus.mipi_csi1.lane_polarity[0];
>  			dev_dbg(dev, "clock lane polarity %u, pos %u\n",
>  				buscfg->bus.ccp2.lanecfg.clk.pol,
>  				buscfg->bus.ccp2.lanecfg.clk.pos);
> 
>  			buscfg->bus.ccp2.lanecfg.data[0].pos =
> -				vep.bus.mipi_csi1.data_lane;
> +				vep->bus.mipi_csi1.data_lane;
>  			buscfg->bus.ccp2.lanecfg.data[0].pol =
> -				vep.bus.mipi_csi1.lane_polarity[1];
> +				vep->bus.mipi_csi1.lane_polarity[1];
> 
>  			dev_dbg(dev, "data lane polarity %u, pos %u\n",
>  				buscfg->bus.ccp2.lanecfg.data[0].pol,
>  				buscfg->bus.ccp2.lanecfg.data[0].pos);
> 
>  			buscfg->bus.ccp2.strobe_clk_pol =
> -				vep.bus.mipi_csi1.clock_inv;
> -			buscfg->bus.ccp2.phy_layer = vep.bus.mipi_csi1.strobe;
> +				vep->bus.mipi_csi1.clock_inv;
> +			buscfg->bus.ccp2.phy_layer = vep->bus.mipi_csi1.strobe;
>  			buscfg->bus.ccp2.ccp2_mode =
> -				vep.bus_type == V4L2_MBUS_CCP2;
> +				vep->bus_type == V4L2_MBUS_CCP2;
>  			buscfg->bus.ccp2.vp_clk_pol = 1;
> 
>  			buscfg->bus.ccp2.crc = 1;
>  		} else {
>  			buscfg->bus.csi2.lanecfg.clk.pos =
> -				vep.bus.mipi_csi2.clock_lane;
> +				vep->bus.mipi_csi2.clock_lane;
>  			buscfg->bus.csi2.lanecfg.clk.pol =
> -				vep.bus.mipi_csi2.lane_polarities[0];
> +				vep->bus.mipi_csi2.lane_polarities[0];
>  			dev_dbg(dev, "clock lane polarity %u, pos %u\n",
>  				buscfg->bus.csi2.lanecfg.clk.pol,
>  				buscfg->bus.csi2.lanecfg.clk.pos);
> 
>  			buscfg->bus.csi2.num_data_lanes =
> -				vep.bus.mipi_csi2.num_data_lanes;
> +				vep->bus.mipi_csi2.num_data_lanes;
> 
>  			for (i = 0; i < buscfg->bus.csi2.num_data_lanes; i++) {
>  				buscfg->bus.csi2.lanecfg.data[i].pos =
> -					vep.bus.mipi_csi2.data_lanes[i];
> +					vep->bus.mipi_csi2.data_lanes[i];
>  				buscfg->bus.csi2.lanecfg.data[i].pol =
> -					vep.bus.mipi_csi2.lane_polarities[i + 1];
> +					vep->bus.mipi_csi2.lane_polarities[i + 1];
>  				dev_dbg(dev,
>  					"data lane %u polarity %u, pos %u\n", i,
>  					buscfg->bus.csi2.lanecfg.data[i].pol,
> @@ -2137,57 +2135,13 @@ static int isp_fwnode_parse(struct device *dev,
> struct fwnode_handle *fwnode,
> 
>  	default:
>  		dev_warn(dev, "%pOF: invalid interface %u\n",
> -			 to_of_node(fwnode), vep.base.port);
> +			 to_of_node(vep->base.local_fwnode), vep->base.port);
>  		return -EINVAL;
>  	}
> 
>  	return 0;
>  }
> 
> -static int isp_fwnodes_parse(struct device *dev,
> -			     struct v4l2_async_notifier *notifier)
> -{
> -	struct fwnode_handle *fwnode = NULL;
> -
> -	notifier->subdevs = devm_kcalloc(
> -		dev, ISP_MAX_SUBDEVS, sizeof(*notifier->subdevs), GFP_KERNEL);
> -	if (!notifier->subdevs)
> -		return -ENOMEM;
> -
> -	while (notifier->num_subdevs < ISP_MAX_SUBDEVS &&
> -	       (fwnode = fwnode_graph_get_next_endpoint(
> -			of_fwnode_handle(dev->of_node), fwnode))) {
> -		struct isp_async_subdev *isd;
> -
> -		isd = devm_kzalloc(dev, sizeof(*isd), GFP_KERNEL);
> -		if (!isd)
> -			goto error;
> -
> -		if (isp_fwnode_parse(dev, fwnode, isd)) {
> -			devm_kfree(dev, isd);
> -			continue;
> -		}
> -
> -		notifier->subdevs[notifier->num_subdevs] = &isd->asd;
> -
> -		isd->asd.match.fwnode.fwnode =
> -			fwnode_graph_get_remote_port_parent(fwnode);
> -		if (!isd->asd.match.fwnode.fwnode) {
> -			dev_warn(dev, "bad remote port parent\n");
> -			goto error;
> -		}
> -
> -		isd->asd.match_type = V4L2_ASYNC_MATCH_FWNODE;
> -		notifier->num_subdevs++;
> -	}
> -
> -	return notifier->num_subdevs;
> -
> -error:
> -	fwnode_handle_put(fwnode);
> -	return -EINVAL;
> -}
> -
>  static int isp_subdev_notifier_complete(struct v4l2_async_notifier *async)
>  {
>  	struct isp_device *isp = container_of(async, struct isp_device,
> @@ -2256,7 +2210,9 @@ static int isp_probe(struct platform_device *pdev)
>  	if (ret)
>  		return ret;
> 
> -	ret = isp_fwnodes_parse(&pdev->dev, &isp->notifier);
> +	ret = v4l2_async_notifier_parse_fwnode_endpoints(
> +		&pdev->dev, &isp->notifier, sizeof(struct isp_async_subdev),
> +		isp_fwnode_parse);
>  	if (ret < 0)
>  		return ret;
> 
> @@ -2407,6 +2363,7 @@ static int isp_probe(struct platform_device *pdev)
>  	__omap3isp_put(isp, false);
>  error:
>  	mutex_destroy(&isp->isp_mutex);
> +	v4l2_async_notifier_release(&isp->notifier);
> 
>  	return ret;
>  }
> diff --git a/drivers/media/platform/omap3isp/isp.h
> b/drivers/media/platform/omap3isp/isp.h index e528df6efc09..8b9043db94b3
> 100644
> --- a/drivers/media/platform/omap3isp/isp.h
> +++ b/drivers/media/platform/omap3isp/isp.h
> @@ -220,14 +220,11 @@ struct isp_device {
> 
>  	unsigned int sbl_resources;
>  	unsigned int subclk_resources;
> -
> -#define ISP_MAX_SUBDEVS		8
> -	struct v4l2_subdev *subdevs[ISP_MAX_SUBDEVS];
>  };
> 
>  struct isp_async_subdev {
> -	struct isp_bus_cfg bus;
>  	struct v4l2_async_subdev asd;
> +	struct isp_bus_cfg bus;
>  };
> 
>  #define v4l2_subdev_to_bus_cfg(sd) \
> diff --git a/drivers/media/v4l2-core/v4l2-async.c
> b/drivers/media/v4l2-core/v4l2-async.c index 851f128eba22..c490acf5ae82
> 100644
> --- a/drivers/media/v4l2-core/v4l2-async.c
> +++ b/drivers/media/v4l2-core/v4l2-async.c
> @@ -22,6 +22,7 @@
> 
>  #include <media/v4l2-async.h>
>  #include <media/v4l2-device.h>
> +#include <media/v4l2-fwnode.h>
>  #include <media/v4l2-subdev.h>
> 
>  static bool match_i2c(struct v4l2_subdev *sd, struct v4l2_async_subdev
> *asd) @@ -278,6 +279,21 @@ void v4l2_async_notifier_unregister(struct
> v4l2_async_notifier *notifier) }
>  EXPORT_SYMBOL(v4l2_async_notifier_unregister);
> 
> +void v4l2_async_notifier_release(struct v4l2_async_notifier *notifier)
> +{
> +	unsigned int i;
> +
> +	if (!notifier->max_subdevs)
> +		return;
> +
> +	for (i = 0; i < notifier->num_subdevs; i++)
> +		kfree(notifier->subdevs[i]);
> +
> +	kvfree(notifier->subdevs);
> +	notifier->max_subdevs = 0;
> +}
> +EXPORT_SYMBOL_GPL(v4l2_async_notifier_release);
> +
>  int v4l2_async_register_subdev(struct v4l2_subdev *sd)
>  {
>  	struct v4l2_async_notifier *notifier;
> diff --git a/drivers/media/v4l2-core/v4l2-fwnode.c
> b/drivers/media/v4l2-core/v4l2-fwnode.c index 706f9e7b90f1..39a587c6992a
> 100644
> --- a/drivers/media/v4l2-core/v4l2-fwnode.c
> +++ b/drivers/media/v4l2-core/v4l2-fwnode.c
> @@ -19,6 +19,7 @@
>   */
>  #include <linux/acpi.h>
>  #include <linux/kernel.h>
> +#include <linux/mm.h>
>  #include <linux/module.h>
>  #include <linux/of.h>
>  #include <linux/property.h>
> @@ -26,6 +27,7 @@
>  #include <linux/string.h>
>  #include <linux/types.h>
> 
> +#include <media/v4l2-async.h>
>  #include <media/v4l2-fwnode.h>
> 
>  enum v4l2_fwnode_bus_type {
> @@ -313,6 +315,136 @@ void v4l2_fwnode_put_link(struct v4l2_fwnode_link
> *link) }
>  EXPORT_SYMBOL_GPL(v4l2_fwnode_put_link);
> 
> +static int notifier_realloc(struct v4l2_async_notifier *notifier,
> +			    unsigned int max_subdevs)

I'd prefix static functions with v4l2_async_ to avoid namespace clashes.

> +{
> +	struct v4l2_async_subdev **subdevs;
> +	unsigned int i;
> +
> +	if (max_subdevs <= notifier->max_subdevs)
> +		return 0;
> +
> +	subdevs = kvmalloc_array(
> +		max_subdevs, sizeof(*notifier->subdevs),
> +		GFP_KERNEL | __GFP_ZERO);

Should it be mentioned in the documentation that the address of the subdevs 
array will change during parsing and should not be stored by drivers ? It 
might be overkill.

> +	if (!subdevs)
> +		return -ENOMEM;
> +
> +	if (notifier->subdevs) {
> +		for (i = 0; i < notifier->num_subdevs; i++)
> +			subdevs[i] = notifier->subdevs[i];

To answer your previous question, yes, I would find

	memcpy(subdevs, notifier->subdevs, sizeof(*subdevs) * num_subdevs);

easier to read :-)

> +		kvfree(notifier->subdevs);
> +	}
> +
> +	notifier->subdevs = subdevs;
> +	notifier->max_subdevs = max_subdevs;
> +
> +	return 0;
> +}
> +
> +static int parse_endpoint(
> +	struct device *dev, struct v4l2_async_notifier *notifier,
> +	struct fwnode_handle *endpoint, unsigned int asd_struct_size,
> +	int (*parse_single)(struct device *dev,
> +			    struct v4l2_fwnode_endpoint *vep,
> +			    struct v4l2_async_subdev *asd))
> +{
> +	struct v4l2_async_subdev *asd;
> +	struct v4l2_fwnode_endpoint *vep;
> +	int ret = 0;
> +
> +	asd = kzalloc(asd_struct_size, GFP_KERNEL);
> +	if (!asd)
> +		return -ENOMEM;
> +
> +	asd->match.fwnode.fwnode =
> +		fwnode_graph_get_remote_port_parent(endpoint);
> +	if (!asd->match.fwnode.fwnode) {
> +		dev_warn(dev, "bad remote port parent\n");
> +		ret = -EINVAL;
> +		goto out_err;
> +	}
> +
> +	/* Ignore endpoints the parsing of which failed. */

You don't ignore them anymore, the comment should be updated.

> +	vep = v4l2_fwnode_endpoint_alloc_parse(endpoint);
> +	if (IS_ERR(vep)) {
> +		ret = PTR_ERR(vep);
> +		dev_warn(dev, "unable to parse V4L2 fwnode endpoint (%d)\n",
> +			 ret);
> +		goto out_err;
> +	}
> +
> +	ret = parse_single(dev, vep, asd);
> +	v4l2_fwnode_endpoint_free(vep);
> +	if (ret) {
> +		dev_warn(dev, "driver could not parse endpoint (%d)\n", ret);
> +		goto out_err;
> +	}
> +
> +	asd->match_type = V4L2_ASYNC_MATCH_FWNODE;
> +	notifier->subdevs[notifier->num_subdevs] = asd;
> +	notifier->num_subdevs++;
> +
> +	return 0;
> +
> +out_err:
> +	fwnode_handle_put(asd->match.fwnode.fwnode);
> +	kfree(asd);
> +
> +	return ret;
> +}
> +
> +int v4l2_async_notifier_parse_fwnode_endpoints(
> +	struct device *dev, struct v4l2_async_notifier *notifier,
> +	size_t asd_struct_size,
> +	int (*parse_single)(struct device *dev,
> +			    struct v4l2_fwnode_endpoint *vep,
> +			    struct v4l2_async_subdev *asd))
> +{
> +	struct fwnode_handle *fwnode = NULL;
> +	unsigned int max_subdevs = notifier->max_subdevs;
> +	int ret;
> +
> +	if (asd_struct_size < sizeof(struct v4l2_async_subdev) ||
> +	    notifier->v4l2_dev)
> +		return -EINVAL;
> +
> +	for (fwnode = NULL; (fwnode = fwnode_graph_get_next_endpoint(
> +				     dev_fwnode(dev), fwnode)); )
> +		if (fwnode_device_is_available(
> +			    fwnode_graph_get_port_parent(fwnode)))
> +			max_subdevs++;
> +
> +	/* No subdevs to add? Return here. */
> +	if (max_subdevs == notifier->max_subdevs)
> +		return 0;
> +
> +	ret = notifier_realloc(notifier, max_subdevs);
> +	if (ret)
> +		return ret;
> +
> +	for (fwnode = NULL; (fwnode = fwnode_graph_get_next_endpoint(
> +				     dev_fwnode(dev), fwnode)); ) {
> +		if (!fwnode_device_is_available(
> +			    fwnode_graph_get_port_parent(fwnode)))
> +			continue;
> +
> +		if (WARN_ON(notifier->num_subdevs >= notifier->max_subdevs))
> +			break;
> +
> +		ret = parse_endpoint(dev, notifier, fwnode, asd_struct_size,
> +				     parse_single);
> +		if (ret < 0)
> +			break;
> +	}
> +
> +	fwnode_handle_put(fwnode);
> +
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(v4l2_async_notifier_parse_fwnode_endpoints);
> +
>  MODULE_LICENSE("GPL");
>  MODULE_AUTHOR("Sakari Ailus <sakari.ailus-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>");
>  MODULE_AUTHOR("Sylwester Nawrocki <s.nawrocki-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org>");
> diff --git a/include/media/v4l2-async.h b/include/media/v4l2-async.h
> index c69d8c8a66d0..4a44ab47ab04 100644
> --- a/include/media/v4l2-async.h
> +++ b/include/media/v4l2-async.h
> @@ -18,7 +18,6 @@ struct device;
>  struct device_node;
>  struct v4l2_device;
>  struct v4l2_subdev;
> -struct v4l2_async_notifier;
> 
>  /* A random max subdevice number, used to allocate an array on stack */
>  #define V4L2_MAX_SUBDEVS 128U
> @@ -78,7 +77,8 @@ struct v4l2_async_subdev {
>  /**
>   * struct v4l2_async_notifier - v4l2_device notifier data
>   *
> - * @num_subdevs: number of subdevices
> + * @num_subdevs: number of subdevices used in subdevs array
> + * @max_subdevs: number of subdevices allocated in subdevs array
>   * @subdevs:	array of pointers to subdevice descriptors
>   * @v4l2_dev:	pointer to struct v4l2_device
>   * @waiting:	list of struct v4l2_async_subdev, waiting for their drivers
> @@ -90,6 +90,7 @@ struct v4l2_async_subdev {
>   */
>  struct v4l2_async_notifier {
>  	unsigned int num_subdevs;
> +	unsigned int max_subdevs;
>  	struct v4l2_async_subdev **subdevs;
>  	struct v4l2_device *v4l2_dev;
>  	struct list_head waiting;
> @@ -121,6 +122,21 @@ int v4l2_async_notifier_register(struct v4l2_device
> *v4l2_dev, void v4l2_async_notifier_unregister(struct v4l2_async_notifier
> *notifier);
> 
>  /**
> + * v4l2_async_notifier_release - release notifier resources
> + * @notifier: pointer to &struct v4l2_async_notifier

That's quite obvious given the type of the argument. It would be much more 
useful to tell which notifier pointer this function expects (although in this 
case it should be obvious too): "(pointer to )?the notifier whose resources 
will be released".

> + *
> + * Release memory resources related to a notifier, including the async
> + * sub-devices allocated for the purposes of the notifier. The user is
> + * responsible for releasing the notifier's resources after calling
> + * @v4l2_async_notifier_parse_fwnode_endpoints.
> + *
> + * There is no harm from calling v4l2_async_notifier_release in other
> + * cases as long as its memory has been zeroed after it has been
> + * allocated.

Zeroing the memory is pretty much a requirement, as 
v4l2_async_notifier_parse_fwnode_endpoints() won't operate correctly if memory 
contains random data anyway. Maybe we should introduce 
v4l2_async_notifier_init() and make v4l2_async_notifier_release() mandatory, 
but that's out of scope for this patch.

> + */
> +void v4l2_async_notifier_release(struct v4l2_async_notifier *notifier);
> +
> +/**
>   * v4l2_async_register_subdev - registers a sub-device to the asynchronous
>   * 	subdevice framework
>   *
> diff --git a/include/media/v4l2-fwnode.h b/include/media/v4l2-fwnode.h
> index 68eb22ba571b..46521e8c8872 100644
> --- a/include/media/v4l2-fwnode.h
> +++ b/include/media/v4l2-fwnode.h
> @@ -25,6 +25,8 @@
>  #include <media/v4l2-mediabus.h>
> 
>  struct fwnode_handle;
> +struct v4l2_async_notifier;
> +struct v4l2_async_subdev;
> 
>  #define V4L2_FWNODE_CSI2_MAX_DATA_LANES	4
> 
> @@ -201,4 +203,41 @@ int v4l2_fwnode_parse_link(struct fwnode_handle
> *fwnode, */
>  void v4l2_fwnode_put_link(struct v4l2_fwnode_link *link);
> 
> +/**
> + * v4l2_async_notifier_parse_fwnode_endpoints - Parse V4L2 fwnode endpoints
> in a
> + *						device node
> + * @dev: @struct device pointer

Similarly to my previous comment (and my comments to v3), you should tell 
which device the function expects.

> + * @notifier: pointer to &struct v4l2_async_notifier
> + * @asd_struct_size: size of the driver's async sub-device struct,
> including
> + *		     sizeof(struct v4l2_async_subdev). The &struct
> + *		     v4l2_async_subdev shall be the first member of
> + *		     the driver's async sub-device struct, i.e. both
> + *		     begin at the same memory address.

Should this be documented in the kerneldoc of the v4l2_async_subdev structure 
?

> + * @parse_single: driver's callback function called on each V4L2 fwnode
> endpoint
> + *
> + * Allocate async sub-device array and sub-devices for each fwnode
> endpoint,
> + * parse the related fwnode endpoints and finally call driver's callback
> + * function to that V4L2 fwnode endpoint.

I'd document this from the notifier point of view.

"Parse the fwnode endpoints of the @dev device and populate the async sub-
devices array of the notifier. The @parse_endpoint callback function is called 
for each endpoint with the corresponding async sub-device pointer to let the 
caller initialize the driver-specific part of the async sub-device structure."

> + * The function may not be called on a registered notifier.

You should mention that the function may be called multiple times on an 
unregistered notifier.

"The function can be called multiple times to populate the same notifier from 
endpoints of different @dev devices before registering the notifier. It can't 
be called anymore once the notifier has been registered."

> + *
> + * Once the user has called this function, the resources released by it
> need to
> + * be released by callin v4l2_async_notifier_release after the notifier has
> been
> + * unregistered and the sub-devices are no longer in use.

"Any notifier populated using this function must be released with a call to 
v4l2_async_notifier_release() after it has been unregistered and the async 
sub-devices are no longer in use."

> + *
> + * A driver supporting fwnode (currently Devicetree and ACPI) should call
> this
> + * function as part of its probe function before it registers the notifier.
> + *
> + * Return: %0 on success, including when no async sub-devices are found
> + *	   %-ENOMEM if memory allocation failed
> + *	   %-EINVAL if graph or endpoint parsing failed
> + *	   Other error codes as returned by @parse_single
> + */
> +int v4l2_async_notifier_parse_fwnode_endpoints(
> +	struct device *dev, struct v4l2_async_notifier *notifier,
> +	size_t asd_struct_size,
> +	int (*parse_single)(struct device *dev,
> +			    struct v4l2_fwnode_endpoint *vep,
> +			    struct v4l2_async_subdev *asd));
> +
>  #endif /* _V4L2_FWNODE_H */


-- 
Regards,

Laurent Pinchart

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WARNING: multiple messages have this Message-ID
From: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
To: Sakari Ailus <sakari.ailus@linux.intel.com>
Cc: linux-media@vger.kernel.org, niklas.soderlund@ragnatech.se,
	robh@kernel.org, hverkuil@xs4all.nl, devicetree@vger.kernel.org
Subject: Re: [PATCH v5 4/5] v4l: fwnode: Support generic parsing of graph endpoints in a device
Date: Tue, 29 Aug 2017 17:02:54 +0300	[thread overview]
Message-ID: <2739432.dQ1BSg1MPy@avalon> (raw)
In-Reply-To: <20170829110313.19538-5-sakari.ailus@linux.intel.com>

Hi Sakari,

Thank you for the patch.

On Tuesday, 29 August 2017 14:03:12 EEST Sakari Ailus wrote:
> The current practice is that drivers iterate over their endpoints and
> parse each endpoint separately. This is very similar in a number of
> drivers, implement a generic function for the job. Driver specific matters
> can be taken into account in the driver specific callback.
> 
> Convert the omap3isp as an example.
> 
> Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
> ---
>  drivers/media/platform/omap3isp/isp.c | 115 ++++++++++-------------------
>  drivers/media/platform/omap3isp/isp.h |   5 +-
>  drivers/media/v4l2-core/v4l2-async.c  |  16 +++++
>  drivers/media/v4l2-core/v4l2-fwnode.c | 132
> ++++++++++++++++++++++++++++++++++ include/media/v4l2-async.h            | 
> 20 +++++-
>  include/media/v4l2-fwnode.h           |  39 ++++++++++
>  6 files changed, 242 insertions(+), 85 deletions(-)
> 
> diff --git a/drivers/media/platform/omap3isp/isp.c
> b/drivers/media/platform/omap3isp/isp.c index 1a428fe9f070..a546cf774d40
> 100644
> --- a/drivers/media/platform/omap3isp/isp.c
> +++ b/drivers/media/platform/omap3isp/isp.c
> @@ -2001,6 +2001,7 @@ static int isp_remove(struct platform_device *pdev)
>  	__omap3isp_put(isp, false);
> 
>  	media_entity_enum_cleanup(&isp->crashed);
> +	v4l2_async_notifier_release(&isp->notifier);
> 
>  	return 0;
>  }
> @@ -2011,44 +2012,41 @@ enum isp_of_phy {
>  	ISP_OF_PHY_CSIPHY2,
>  };
> 
> -static int isp_fwnode_parse(struct device *dev, struct fwnode_handle
> *fwnode, -			    struct isp_async_subdev *isd)
> +static int isp_fwnode_parse(struct device *dev,
> +			    struct v4l2_fwnode_endpoint *vep,
> +			    struct v4l2_async_subdev *asd)
>  {
> +	struct isp_async_subdev *isd =
> +		container_of(asd, struct isp_async_subdev, asd);
>  	struct isp_bus_cfg *buscfg = &isd->bus;
> -	struct v4l2_fwnode_endpoint vep;
> -	unsigned int i;
> -	int ret;
>  	bool csi1 = false;
> -
> -	ret = v4l2_fwnode_endpoint_parse(fwnode, &vep);
> -	if (ret)
> -		return ret;
> +	unsigned int i;
> 
>  	dev_dbg(dev, "parsing endpoint %pOF, interface %u\n",
> -		to_of_node(fwnode), vep.base.port);
> +		to_of_node(vep->base.local_fwnode), vep->base.port);
> 
> -	switch (vep.base.port) {
> +	switch (vep->base.port) {
>  	case ISP_OF_PHY_PARALLEL:
>  		buscfg->interface = ISP_INTERFACE_PARALLEL;
>  		buscfg->bus.parallel.data_lane_shift =
> -			vep.bus.parallel.data_shift;
> +			vep->bus.parallel.data_shift;
>  		buscfg->bus.parallel.clk_pol =
> -			!!(vep.bus.parallel.flags
> +			!!(vep->bus.parallel.flags
>  			   & V4L2_MBUS_PCLK_SAMPLE_FALLING);
>  		buscfg->bus.parallel.hs_pol =
> -			!!(vep.bus.parallel.flags & V4L2_MBUS_VSYNC_ACTIVE_LOW);
> +			!!(vep->bus.parallel.flags & V4L2_MBUS_VSYNC_ACTIVE_LOW);
>  		buscfg->bus.parallel.vs_pol =
> -			!!(vep.bus.parallel.flags & V4L2_MBUS_HSYNC_ACTIVE_LOW);
> +			!!(vep->bus.parallel.flags & V4L2_MBUS_HSYNC_ACTIVE_LOW);
>  		buscfg->bus.parallel.fld_pol =
> -			!!(vep.bus.parallel.flags & V4L2_MBUS_FIELD_EVEN_LOW);
> +			!!(vep->bus.parallel.flags & V4L2_MBUS_FIELD_EVEN_LOW);
>  		buscfg->bus.parallel.data_pol =
> -			!!(vep.bus.parallel.flags & V4L2_MBUS_DATA_ACTIVE_LOW);
> -		buscfg->bus.parallel.bt656 = vep.bus_type == V4L2_MBUS_BT656;
> +			!!(vep->bus.parallel.flags & V4L2_MBUS_DATA_ACTIVE_LOW);
> +		buscfg->bus.parallel.bt656 = vep->bus_type == V4L2_MBUS_BT656;
>  		break;
> 
>  	case ISP_OF_PHY_CSIPHY1:
>  	case ISP_OF_PHY_CSIPHY2:
> -		switch (vep.bus_type) {
> +		switch (vep->bus_type) {
>  		case V4L2_MBUS_CCP2:
>  		case V4L2_MBUS_CSI1:
>  			dev_dbg(dev, "CSI-1/CCP-2 configuration\n");
> @@ -2060,11 +2058,11 @@ static int isp_fwnode_parse(struct device *dev,
> struct fwnode_handle *fwnode, break;
>  		default:
>  			dev_err(dev, "unsupported bus type %u\n",
> -				vep.bus_type);
> +				vep->bus_type);
>  			return -EINVAL;
>  		}
> 
> -		switch (vep.base.port) {
> +		switch (vep->base.port) {
>  		case ISP_OF_PHY_CSIPHY1:
>  			if (csi1)
>  				buscfg->interface = ISP_INTERFACE_CCP2B_PHY1;
> @@ -2080,47 +2078,47 @@ static int isp_fwnode_parse(struct device *dev,
> struct fwnode_handle *fwnode, }
>  		if (csi1) {
>  			buscfg->bus.ccp2.lanecfg.clk.pos =
> -				vep.bus.mipi_csi1.clock_lane;
> +				vep->bus.mipi_csi1.clock_lane;
>  			buscfg->bus.ccp2.lanecfg.clk.pol =
> -				vep.bus.mipi_csi1.lane_polarity[0];
> +				vep->bus.mipi_csi1.lane_polarity[0];
>  			dev_dbg(dev, "clock lane polarity %u, pos %u\n",
>  				buscfg->bus.ccp2.lanecfg.clk.pol,
>  				buscfg->bus.ccp2.lanecfg.clk.pos);
> 
>  			buscfg->bus.ccp2.lanecfg.data[0].pos =
> -				vep.bus.mipi_csi1.data_lane;
> +				vep->bus.mipi_csi1.data_lane;
>  			buscfg->bus.ccp2.lanecfg.data[0].pol =
> -				vep.bus.mipi_csi1.lane_polarity[1];
> +				vep->bus.mipi_csi1.lane_polarity[1];
> 
>  			dev_dbg(dev, "data lane polarity %u, pos %u\n",
>  				buscfg->bus.ccp2.lanecfg.data[0].pol,
>  				buscfg->bus.ccp2.lanecfg.data[0].pos);
> 
>  			buscfg->bus.ccp2.strobe_clk_pol =
> -				vep.bus.mipi_csi1.clock_inv;
> -			buscfg->bus.ccp2.phy_layer = vep.bus.mipi_csi1.strobe;
> +				vep->bus.mipi_csi1.clock_inv;
> +			buscfg->bus.ccp2.phy_layer = vep->bus.mipi_csi1.strobe;
>  			buscfg->bus.ccp2.ccp2_mode =
> -				vep.bus_type == V4L2_MBUS_CCP2;
> +				vep->bus_type == V4L2_MBUS_CCP2;
>  			buscfg->bus.ccp2.vp_clk_pol = 1;
> 
>  			buscfg->bus.ccp2.crc = 1;
>  		} else {
>  			buscfg->bus.csi2.lanecfg.clk.pos =
> -				vep.bus.mipi_csi2.clock_lane;
> +				vep->bus.mipi_csi2.clock_lane;
>  			buscfg->bus.csi2.lanecfg.clk.pol =
> -				vep.bus.mipi_csi2.lane_polarities[0];
> +				vep->bus.mipi_csi2.lane_polarities[0];
>  			dev_dbg(dev, "clock lane polarity %u, pos %u\n",
>  				buscfg->bus.csi2.lanecfg.clk.pol,
>  				buscfg->bus.csi2.lanecfg.clk.pos);
> 
>  			buscfg->bus.csi2.num_data_lanes =
> -				vep.bus.mipi_csi2.num_data_lanes;
> +				vep->bus.mipi_csi2.num_data_lanes;
> 
>  			for (i = 0; i < buscfg->bus.csi2.num_data_lanes; i++) {
>  				buscfg->bus.csi2.lanecfg.data[i].pos =
> -					vep.bus.mipi_csi2.data_lanes[i];
> +					vep->bus.mipi_csi2.data_lanes[i];
>  				buscfg->bus.csi2.lanecfg.data[i].pol =
> -					vep.bus.mipi_csi2.lane_polarities[i + 1];
> +					vep->bus.mipi_csi2.lane_polarities[i + 1];
>  				dev_dbg(dev,
>  					"data lane %u polarity %u, pos %u\n", i,
>  					buscfg->bus.csi2.lanecfg.data[i].pol,
> @@ -2137,57 +2135,13 @@ static int isp_fwnode_parse(struct device *dev,
> struct fwnode_handle *fwnode,
> 
>  	default:
>  		dev_warn(dev, "%pOF: invalid interface %u\n",
> -			 to_of_node(fwnode), vep.base.port);
> +			 to_of_node(vep->base.local_fwnode), vep->base.port);
>  		return -EINVAL;
>  	}
> 
>  	return 0;
>  }
> 
> -static int isp_fwnodes_parse(struct device *dev,
> -			     struct v4l2_async_notifier *notifier)
> -{
> -	struct fwnode_handle *fwnode = NULL;
> -
> -	notifier->subdevs = devm_kcalloc(
> -		dev, ISP_MAX_SUBDEVS, sizeof(*notifier->subdevs), GFP_KERNEL);
> -	if (!notifier->subdevs)
> -		return -ENOMEM;
> -
> -	while (notifier->num_subdevs < ISP_MAX_SUBDEVS &&
> -	       (fwnode = fwnode_graph_get_next_endpoint(
> -			of_fwnode_handle(dev->of_node), fwnode))) {
> -		struct isp_async_subdev *isd;
> -
> -		isd = devm_kzalloc(dev, sizeof(*isd), GFP_KERNEL);
> -		if (!isd)
> -			goto error;
> -
> -		if (isp_fwnode_parse(dev, fwnode, isd)) {
> -			devm_kfree(dev, isd);
> -			continue;
> -		}
> -
> -		notifier->subdevs[notifier->num_subdevs] = &isd->asd;
> -
> -		isd->asd.match.fwnode.fwnode =
> -			fwnode_graph_get_remote_port_parent(fwnode);
> -		if (!isd->asd.match.fwnode.fwnode) {
> -			dev_warn(dev, "bad remote port parent\n");
> -			goto error;
> -		}
> -
> -		isd->asd.match_type = V4L2_ASYNC_MATCH_FWNODE;
> -		notifier->num_subdevs++;
> -	}
> -
> -	return notifier->num_subdevs;
> -
> -error:
> -	fwnode_handle_put(fwnode);
> -	return -EINVAL;
> -}
> -
>  static int isp_subdev_notifier_complete(struct v4l2_async_notifier *async)
>  {
>  	struct isp_device *isp = container_of(async, struct isp_device,
> @@ -2256,7 +2210,9 @@ static int isp_probe(struct platform_device *pdev)
>  	if (ret)
>  		return ret;
> 
> -	ret = isp_fwnodes_parse(&pdev->dev, &isp->notifier);
> +	ret = v4l2_async_notifier_parse_fwnode_endpoints(
> +		&pdev->dev, &isp->notifier, sizeof(struct isp_async_subdev),
> +		isp_fwnode_parse);
>  	if (ret < 0)
>  		return ret;
> 
> @@ -2407,6 +2363,7 @@ static int isp_probe(struct platform_device *pdev)
>  	__omap3isp_put(isp, false);
>  error:
>  	mutex_destroy(&isp->isp_mutex);
> +	v4l2_async_notifier_release(&isp->notifier);
> 
>  	return ret;
>  }
> diff --git a/drivers/media/platform/omap3isp/isp.h
> b/drivers/media/platform/omap3isp/isp.h index e528df6efc09..8b9043db94b3
> 100644
> --- a/drivers/media/platform/omap3isp/isp.h
> +++ b/drivers/media/platform/omap3isp/isp.h
> @@ -220,14 +220,11 @@ struct isp_device {
> 
>  	unsigned int sbl_resources;
>  	unsigned int subclk_resources;
> -
> -#define ISP_MAX_SUBDEVS		8
> -	struct v4l2_subdev *subdevs[ISP_MAX_SUBDEVS];
>  };
> 
>  struct isp_async_subdev {
> -	struct isp_bus_cfg bus;
>  	struct v4l2_async_subdev asd;
> +	struct isp_bus_cfg bus;
>  };
> 
>  #define v4l2_subdev_to_bus_cfg(sd) \
> diff --git a/drivers/media/v4l2-core/v4l2-async.c
> b/drivers/media/v4l2-core/v4l2-async.c index 851f128eba22..c490acf5ae82
> 100644
> --- a/drivers/media/v4l2-core/v4l2-async.c
> +++ b/drivers/media/v4l2-core/v4l2-async.c
> @@ -22,6 +22,7 @@
> 
>  #include <media/v4l2-async.h>
>  #include <media/v4l2-device.h>
> +#include <media/v4l2-fwnode.h>
>  #include <media/v4l2-subdev.h>
> 
>  static bool match_i2c(struct v4l2_subdev *sd, struct v4l2_async_subdev
> *asd) @@ -278,6 +279,21 @@ void v4l2_async_notifier_unregister(struct
> v4l2_async_notifier *notifier) }
>  EXPORT_SYMBOL(v4l2_async_notifier_unregister);
> 
> +void v4l2_async_notifier_release(struct v4l2_async_notifier *notifier)
> +{
> +	unsigned int i;
> +
> +	if (!notifier->max_subdevs)
> +		return;
> +
> +	for (i = 0; i < notifier->num_subdevs; i++)
> +		kfree(notifier->subdevs[i]);
> +
> +	kvfree(notifier->subdevs);
> +	notifier->max_subdevs = 0;
> +}
> +EXPORT_SYMBOL_GPL(v4l2_async_notifier_release);
> +
>  int v4l2_async_register_subdev(struct v4l2_subdev *sd)
>  {
>  	struct v4l2_async_notifier *notifier;
> diff --git a/drivers/media/v4l2-core/v4l2-fwnode.c
> b/drivers/media/v4l2-core/v4l2-fwnode.c index 706f9e7b90f1..39a587c6992a
> 100644
> --- a/drivers/media/v4l2-core/v4l2-fwnode.c
> +++ b/drivers/media/v4l2-core/v4l2-fwnode.c
> @@ -19,6 +19,7 @@
>   */
>  #include <linux/acpi.h>
>  #include <linux/kernel.h>
> +#include <linux/mm.h>
>  #include <linux/module.h>
>  #include <linux/of.h>
>  #include <linux/property.h>
> @@ -26,6 +27,7 @@
>  #include <linux/string.h>
>  #include <linux/types.h>
> 
> +#include <media/v4l2-async.h>
>  #include <media/v4l2-fwnode.h>
> 
>  enum v4l2_fwnode_bus_type {
> @@ -313,6 +315,136 @@ void v4l2_fwnode_put_link(struct v4l2_fwnode_link
> *link) }
>  EXPORT_SYMBOL_GPL(v4l2_fwnode_put_link);
> 
> +static int notifier_realloc(struct v4l2_async_notifier *notifier,
> +			    unsigned int max_subdevs)

I'd prefix static functions with v4l2_async_ to avoid namespace clashes.

> +{
> +	struct v4l2_async_subdev **subdevs;
> +	unsigned int i;
> +
> +	if (max_subdevs <= notifier->max_subdevs)
> +		return 0;
> +
> +	subdevs = kvmalloc_array(
> +		max_subdevs, sizeof(*notifier->subdevs),
> +		GFP_KERNEL | __GFP_ZERO);

Should it be mentioned in the documentation that the address of the subdevs 
array will change during parsing and should not be stored by drivers ? It 
might be overkill.

> +	if (!subdevs)
> +		return -ENOMEM;
> +
> +	if (notifier->subdevs) {
> +		for (i = 0; i < notifier->num_subdevs; i++)
> +			subdevs[i] = notifier->subdevs[i];

To answer your previous question, yes, I would find

	memcpy(subdevs, notifier->subdevs, sizeof(*subdevs) * num_subdevs);

easier to read :-)

> +		kvfree(notifier->subdevs);
> +	}
> +
> +	notifier->subdevs = subdevs;
> +	notifier->max_subdevs = max_subdevs;
> +
> +	return 0;
> +}
> +
> +static int parse_endpoint(
> +	struct device *dev, struct v4l2_async_notifier *notifier,
> +	struct fwnode_handle *endpoint, unsigned int asd_struct_size,
> +	int (*parse_single)(struct device *dev,
> +			    struct v4l2_fwnode_endpoint *vep,
> +			    struct v4l2_async_subdev *asd))
> +{
> +	struct v4l2_async_subdev *asd;
> +	struct v4l2_fwnode_endpoint *vep;
> +	int ret = 0;
> +
> +	asd = kzalloc(asd_struct_size, GFP_KERNEL);
> +	if (!asd)
> +		return -ENOMEM;
> +
> +	asd->match.fwnode.fwnode =
> +		fwnode_graph_get_remote_port_parent(endpoint);
> +	if (!asd->match.fwnode.fwnode) {
> +		dev_warn(dev, "bad remote port parent\n");
> +		ret = -EINVAL;
> +		goto out_err;
> +	}
> +
> +	/* Ignore endpoints the parsing of which failed. */

You don't ignore them anymore, the comment should be updated.

> +	vep = v4l2_fwnode_endpoint_alloc_parse(endpoint);
> +	if (IS_ERR(vep)) {
> +		ret = PTR_ERR(vep);
> +		dev_warn(dev, "unable to parse V4L2 fwnode endpoint (%d)\n",
> +			 ret);
> +		goto out_err;
> +	}
> +
> +	ret = parse_single(dev, vep, asd);
> +	v4l2_fwnode_endpoint_free(vep);
> +	if (ret) {
> +		dev_warn(dev, "driver could not parse endpoint (%d)\n", ret);
> +		goto out_err;
> +	}
> +
> +	asd->match_type = V4L2_ASYNC_MATCH_FWNODE;
> +	notifier->subdevs[notifier->num_subdevs] = asd;
> +	notifier->num_subdevs++;
> +
> +	return 0;
> +
> +out_err:
> +	fwnode_handle_put(asd->match.fwnode.fwnode);
> +	kfree(asd);
> +
> +	return ret;
> +}
> +
> +int v4l2_async_notifier_parse_fwnode_endpoints(
> +	struct device *dev, struct v4l2_async_notifier *notifier,
> +	size_t asd_struct_size,
> +	int (*parse_single)(struct device *dev,
> +			    struct v4l2_fwnode_endpoint *vep,
> +			    struct v4l2_async_subdev *asd))
> +{
> +	struct fwnode_handle *fwnode = NULL;
> +	unsigned int max_subdevs = notifier->max_subdevs;
> +	int ret;
> +
> +	if (asd_struct_size < sizeof(struct v4l2_async_subdev) ||
> +	    notifier->v4l2_dev)
> +		return -EINVAL;
> +
> +	for (fwnode = NULL; (fwnode = fwnode_graph_get_next_endpoint(
> +				     dev_fwnode(dev), fwnode)); )
> +		if (fwnode_device_is_available(
> +			    fwnode_graph_get_port_parent(fwnode)))
> +			max_subdevs++;
> +
> +	/* No subdevs to add? Return here. */
> +	if (max_subdevs == notifier->max_subdevs)
> +		return 0;
> +
> +	ret = notifier_realloc(notifier, max_subdevs);
> +	if (ret)
> +		return ret;
> +
> +	for (fwnode = NULL; (fwnode = fwnode_graph_get_next_endpoint(
> +				     dev_fwnode(dev), fwnode)); ) {
> +		if (!fwnode_device_is_available(
> +			    fwnode_graph_get_port_parent(fwnode)))
> +			continue;
> +
> +		if (WARN_ON(notifier->num_subdevs >= notifier->max_subdevs))
> +			break;
> +
> +		ret = parse_endpoint(dev, notifier, fwnode, asd_struct_size,
> +				     parse_single);
> +		if (ret < 0)
> +			break;
> +	}
> +
> +	fwnode_handle_put(fwnode);
> +
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(v4l2_async_notifier_parse_fwnode_endpoints);
> +
>  MODULE_LICENSE("GPL");
>  MODULE_AUTHOR("Sakari Ailus <sakari.ailus@linux.intel.com>");
>  MODULE_AUTHOR("Sylwester Nawrocki <s.nawrocki@samsung.com>");
> diff --git a/include/media/v4l2-async.h b/include/media/v4l2-async.h
> index c69d8c8a66d0..4a44ab47ab04 100644
> --- a/include/media/v4l2-async.h
> +++ b/include/media/v4l2-async.h
> @@ -18,7 +18,6 @@ struct device;
>  struct device_node;
>  struct v4l2_device;
>  struct v4l2_subdev;
> -struct v4l2_async_notifier;
> 
>  /* A random max subdevice number, used to allocate an array on stack */
>  #define V4L2_MAX_SUBDEVS 128U
> @@ -78,7 +77,8 @@ struct v4l2_async_subdev {
>  /**
>   * struct v4l2_async_notifier - v4l2_device notifier data
>   *
> - * @num_subdevs: number of subdevices
> + * @num_subdevs: number of subdevices used in subdevs array
> + * @max_subdevs: number of subdevices allocated in subdevs array
>   * @subdevs:	array of pointers to subdevice descriptors
>   * @v4l2_dev:	pointer to struct v4l2_device
>   * @waiting:	list of struct v4l2_async_subdev, waiting for their drivers
> @@ -90,6 +90,7 @@ struct v4l2_async_subdev {
>   */
>  struct v4l2_async_notifier {
>  	unsigned int num_subdevs;
> +	unsigned int max_subdevs;
>  	struct v4l2_async_subdev **subdevs;
>  	struct v4l2_device *v4l2_dev;
>  	struct list_head waiting;
> @@ -121,6 +122,21 @@ int v4l2_async_notifier_register(struct v4l2_device
> *v4l2_dev, void v4l2_async_notifier_unregister(struct v4l2_async_notifier
> *notifier);
> 
>  /**
> + * v4l2_async_notifier_release - release notifier resources
> + * @notifier: pointer to &struct v4l2_async_notifier

That's quite obvious given the type of the argument. It would be much more 
useful to tell which notifier pointer this function expects (although in this 
case it should be obvious too): "(pointer to )?the notifier whose resources 
will be released".

> + *
> + * Release memory resources related to a notifier, including the async
> + * sub-devices allocated for the purposes of the notifier. The user is
> + * responsible for releasing the notifier's resources after calling
> + * @v4l2_async_notifier_parse_fwnode_endpoints.
> + *
> + * There is no harm from calling v4l2_async_notifier_release in other
> + * cases as long as its memory has been zeroed after it has been
> + * allocated.

Zeroing the memory is pretty much a requirement, as 
v4l2_async_notifier_parse_fwnode_endpoints() won't operate correctly if memory 
contains random data anyway. Maybe we should introduce 
v4l2_async_notifier_init() and make v4l2_async_notifier_release() mandatory, 
but that's out of scope for this patch.

> + */
> +void v4l2_async_notifier_release(struct v4l2_async_notifier *notifier);
> +
> +/**
>   * v4l2_async_register_subdev - registers a sub-device to the asynchronous
>   * 	subdevice framework
>   *
> diff --git a/include/media/v4l2-fwnode.h b/include/media/v4l2-fwnode.h
> index 68eb22ba571b..46521e8c8872 100644
> --- a/include/media/v4l2-fwnode.h
> +++ b/include/media/v4l2-fwnode.h
> @@ -25,6 +25,8 @@
>  #include <media/v4l2-mediabus.h>
> 
>  struct fwnode_handle;
> +struct v4l2_async_notifier;
> +struct v4l2_async_subdev;
> 
>  #define V4L2_FWNODE_CSI2_MAX_DATA_LANES	4
> 
> @@ -201,4 +203,41 @@ int v4l2_fwnode_parse_link(struct fwnode_handle
> *fwnode, */
>  void v4l2_fwnode_put_link(struct v4l2_fwnode_link *link);
> 
> +/**
> + * v4l2_async_notifier_parse_fwnode_endpoints - Parse V4L2 fwnode endpoints
> in a
> + *						device node
> + * @dev: @struct device pointer

Similarly to my previous comment (and my comments to v3), you should tell 
which device the function expects.

> + * @notifier: pointer to &struct v4l2_async_notifier
> + * @asd_struct_size: size of the driver's async sub-device struct,
> including
> + *		     sizeof(struct v4l2_async_subdev). The &struct
> + *		     v4l2_async_subdev shall be the first member of
> + *		     the driver's async sub-device struct, i.e. both
> + *		     begin at the same memory address.

Should this be documented in the kerneldoc of the v4l2_async_subdev structure 
?

> + * @parse_single: driver's callback function called on each V4L2 fwnode
> endpoint
> + *
> + * Allocate async sub-device array and sub-devices for each fwnode
> endpoint,
> + * parse the related fwnode endpoints and finally call driver's callback
> + * function to that V4L2 fwnode endpoint.

I'd document this from the notifier point of view.

"Parse the fwnode endpoints of the @dev device and populate the async sub-
devices array of the notifier. The @parse_endpoint callback function is called 
for each endpoint with the corresponding async sub-device pointer to let the 
caller initialize the driver-specific part of the async sub-device structure."

> + * The function may not be called on a registered notifier.

You should mention that the function may be called multiple times on an 
unregistered notifier.

"The function can be called multiple times to populate the same notifier from 
endpoints of different @dev devices before registering the notifier. It can't 
be called anymore once the notifier has been registered."

> + *
> + * Once the user has called this function, the resources released by it
> need to
> + * be released by callin v4l2_async_notifier_release after the notifier has
> been
> + * unregistered and the sub-devices are no longer in use.

"Any notifier populated using this function must be released with a call to 
v4l2_async_notifier_release() after it has been unregistered and the async 
sub-devices are no longer in use."

> + *
> + * A driver supporting fwnode (currently Devicetree and ACPI) should call
> this
> + * function as part of its probe function before it registers the notifier.
> + *
> + * Return: %0 on success, including when no async sub-devices are found
> + *	   %-ENOMEM if memory allocation failed
> + *	   %-EINVAL if graph or endpoint parsing failed
> + *	   Other error codes as returned by @parse_single
> + */
> +int v4l2_async_notifier_parse_fwnode_endpoints(
> +	struct device *dev, struct v4l2_async_notifier *notifier,
> +	size_t asd_struct_size,
> +	int (*parse_single)(struct device *dev,
> +			    struct v4l2_fwnode_endpoint *vep,
> +			    struct v4l2_async_subdev *asd));
> +
>  #endif /* _V4L2_FWNODE_H */


-- 
Regards,

Laurent Pinchart

  parent reply	other threads:[~2017-08-29 14:02 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-08-29 11:03 [PATCH v5 0/5] Unified fwnode endpoint parser Sakari Ailus
2017-08-29 11:03 ` Sakari Ailus
     [not found] ` <20170829110313.19538-1-sakari.ailus-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
2017-08-29 11:03   ` [PATCH v5 1/5] v4l: fwnode: Move KernelDoc documentation to the header Sakari Ailus
2017-08-29 11:03     ` Sakari Ailus
     [not found]     ` <20170829110313.19538-2-sakari.ailus-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
2017-08-29 12:50       ` Niklas Söderlund
2017-08-29 12:50         ` Niklas Söderlund
2017-08-29 13:15     ` Laurent Pinchart
2017-08-29 13:20       ` Sakari Ailus
2017-08-29 13:20         ` Sakari Ailus
2017-08-29 13:22         ` Sakari Ailus
2017-08-29 11:03   ` [PATCH v5 2/5] v4l: async: Add V4L2 async documentation to the documentation build Sakari Ailus
2017-08-29 11:03     ` Sakari Ailus
2017-08-29 12:52     ` Niklas Söderlund
2017-08-29 11:03   ` [PATCH v5 4/5] v4l: fwnode: Support generic parsing of graph endpoints in a device Sakari Ailus
2017-08-29 11:03     ` Sakari Ailus
     [not found]     ` <20170829110313.19538-5-sakari.ailus-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
2017-08-29 14:02       ` Laurent Pinchart [this message]
2017-08-29 14:02         ` Laurent Pinchart
2017-08-29 14:31         ` Sakari Ailus
2017-08-29 14:31           ` Sakari Ailus
     [not found]           ` <20170829143121.6sjdx3lgcoxm6mva-S+BSfZ9RZZmRSg0ZkenSGLdO1Tsj/99ntUK59QYPAWc@public.gmane.org>
2017-09-01  8:55             ` Laurent Pinchart
2017-09-01  8:55               ` Laurent Pinchart
2017-09-01  9:04               ` Sakari Ailus
2017-08-29 11:03 ` [PATCH v5 3/5] docs-rst: v4l: Include Qualcomm CAMSS in documentation build Sakari Ailus
     [not found]   ` <20170829110313.19538-4-sakari.ailus-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
2017-08-29 13:32     ` Laurent Pinchart
2017-08-29 13:32       ` Laurent Pinchart
2017-08-29 11:03 ` [PATCH v5 5/5] v4l: fwnode: Support generic parsing of graph endpoints in a single port Sakari Ailus
2017-08-29 12:57   ` Niklas Söderlund

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