[PATCH 0/2] Unified fwnode endpoint parser

[PATCH 0/2] Unified fwnode endpoint parser

[Sakari Ailus]

Hi folks,

We have a large influx of new, unmerged, drivers that are now parsing
fwnode endpoints and each one of them is doing this a little bit
differently. The needs are still exactly the same for the graph data
structure is device independent. This is still a non-trivial task and the
majority of the driver implementations are buggy, just buggy in different
ways.

Facilitate parsing endpoints by adding a convenience function for parsing
the endpoints, and make the omap3isp driver use it as an example.

The parser succeeds an essential bugfix in the set.

Sakari Ailus (2):
  v4l: fwnode: link_frequency is an optional property
  v4l: fwnode: Support generic parsing of graph endpoints in V4L2

 drivers/media/platform/omap3isp/isp.c |  91 +++++++------------------
 drivers/media/platform/omap3isp/isp.h |   3 -
 drivers/media/v4l2-core/v4l2-fwnode.c | 124 ++++++++++++++++++++++++++++++----
 include/media/v4l2-async.h            |   4 +-
 include/media/v4l2-fwnode.h           |   9 +++
 5 files changed, 147 insertions(+), 84 deletions(-)

-- 
2.1.4

[PATCH 1/2] v4l: fwnode: link_frequency is an optional property

[Sakari Ailus]

v4l2_fwnode_endpoint_alloc_parse() is intended as a replacement for
v4l2_fwnode_endpoint_parse(). It parses the "link-frequency" property and
if the property isn't found, it returns an error. However,
"link-frequency" is an optional property and if it does not exist is not
an error. Instead, the number of link frequencies is simply zero in that
case.

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
---
 drivers/media/v4l2-core/v4l2-fwnode.c | 30 +++++++++++++++---------------
 1 file changed, 15 insertions(+), 15 deletions(-)

diff --git a/drivers/media/v4l2-core/v4l2-fwnode.c b/drivers/media/v4l2-core/v4l2-fwnode.c
index 153c53c..0ec6c14 100644
--- a/drivers/media/v4l2-core/v4l2-fwnode.c
+++ b/drivers/media/v4l2-core/v4l2-fwnode.c
@@ -247,23 +247,23 @@ struct v4l2_fwnode_endpoint *v4l2_fwnode_endpoint_alloc_parse(
 
 	rval = fwnode_property_read_u64_array(fwnode, "link-frequencies",
 					      NULL, 0);
-	if (rval < 0)
-		goto out_err;
-
-	vep->link_frequencies =
-		kmalloc_array(rval, sizeof(*vep->link_frequencies), GFP_KERNEL);
-	if (!vep->link_frequencies) {
-		rval = -ENOMEM;
-		goto out_err;
-	}
+	if (rval > 0) {
+		vep->link_frequencies =
+			kmalloc_array(rval, sizeof(*vep->link_frequencies),
+				      GFP_KERNEL);
+		if (!vep->link_frequencies) {
+			rval = -ENOMEM;
+			goto out_err;
+		}
 
-	vep->nr_of_link_frequencies = rval;
+		vep->nr_of_link_frequencies = rval;
 
-	rval = fwnode_property_read_u64_array(fwnode, "link-frequencies",
-					      vep->link_frequencies,
-					      vep->nr_of_link_frequencies);
-	if (rval < 0)
-		goto out_err;
+		rval = fwnode_property_read_u64_array(
+			fwnode, "link-frequencies", vep->link_frequencies,
+			vep->nr_of_link_frequencies);
+		if (rval < 0)
+			goto out_err;
+	}
 
 	return vep;
 
-- 
2.1.4

[PATCH 2/2] v4l: fwnode: Support generic parsing of graph endpoints in V4L2

[Sakari Ailus]

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 | 91 ++++++++++-----------------------
 drivers/media/platform/omap3isp/isp.h |  3 --
 drivers/media/v4l2-core/v4l2-fwnode.c | 94 +++++++++++++++++++++++++++++++++++
 include/media/v4l2-async.h            |  4 +-
 include/media/v4l2-fwnode.h           |  9 ++++
 5 files changed, 132 insertions(+), 69 deletions(-)

diff --git a/drivers/media/platform/omap3isp/isp.c b/drivers/media/platform/omap3isp/isp.c
index 9df64c1..9ccf883 100644
--- a/drivers/media/platform/omap3isp/isp.c
+++ b/drivers/media/platform/omap3isp/isp.c
@@ -2008,43 +2008,42 @@ 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;
-
-	ret = v4l2_fwnode_endpoint_parse(fwnode, &vep);
-	if (ret)
-		return ret;
 
 	dev_dbg(dev, "parsing endpoint %s, interface %u\n",
-		to_of_node(fwnode)->full_name, vep.base.port);
+		to_of_node(vep->base.local_fwnode)->full_name, 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);
+			!!(vep->bus.parallel.flags & V4L2_MBUS_DATA_ACTIVE_LOW);
 		break;
 
 	case ISP_OF_PHY_CSIPHY1:
 	case ISP_OF_PHY_CSIPHY2:
 		/* FIXME: always assume CSI-2 for now. */
-		switch (vep.base.port) {
+		switch (vep->base.port) {
 		case ISP_OF_PHY_CSIPHY1:
 			buscfg->interface = ISP_INTERFACE_CSI2C_PHY1;
 			break;
@@ -2052,18 +2051,19 @@ static int isp_fwnode_parse(struct device *dev, struct fwnode_handle *fwnode,
 			buscfg->interface = ISP_INTERFACE_CSI2A_PHY2;
 			break;
 		}
-		buscfg->bus.csi2.lanecfg.clk.pos = vep.bus.mipi_csi2.clock_lane;
+		buscfg->bus.csi2.lanecfg.clk.pos =
+			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);
 
 		for (i = 0; i < ISP_CSIPHY2_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,
 				buscfg->bus.csi2.lanecfg.data[i].pos);
@@ -2079,55 +2079,14 @@ static int isp_fwnode_parse(struct device *dev, struct fwnode_handle *fwnode,
 
 	default:
 		dev_warn(dev, "%s: invalid interface %u\n",
-			 to_of_node(fwnode)->full_name, vep.base.port);
+			 to_of_node(vep->base.local_fwnode)->full_name,
+			 vep->base.port);
 		break;
 	}
 
 	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;
-
-		notifier->subdevs[notifier->num_subdevs] = &isd->asd;
-
-		if (isp_fwnode_parse(dev, fwnode, isd))
-			goto error;
-
-		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_bound(struct v4l2_async_notifier *async,
 				     struct v4l2_subdev *subdev,
 				     struct v4l2_async_subdev *asd)
@@ -2210,7 +2169,9 @@ static int isp_probe(struct platform_device *pdev)
 	if (ret)
 		return ret;
 
-	ret = isp_fwnodes_parse(&pdev->dev, &isp->notifier);
+	ret = v4l2_fwnode_endpoints_parse(
+		&pdev->dev, &isp->notifier, sizeof(struct isp_async_subdev),
+		isp_fwnode_parse);
 	if (ret < 0)
 		return ret;
 
diff --git a/drivers/media/platform/omap3isp/isp.h b/drivers/media/platform/omap3isp/isp.h
index 2f2ae60..a852c11 100644
--- a/drivers/media/platform/omap3isp/isp.h
+++ b/drivers/media/platform/omap3isp/isp.h
@@ -220,9 +220,6 @@ 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 {
diff --git a/drivers/media/v4l2-core/v4l2-fwnode.c b/drivers/media/v4l2-core/v4l2-fwnode.c
index 0ec6c14..b35d525 100644
--- a/drivers/media/v4l2-core/v4l2-fwnode.c
+++ b/drivers/media/v4l2-core/v4l2-fwnode.c
@@ -26,6 +26,7 @@
 #include <linux/string.h>
 #include <linux/types.h>
 
+#include <media/v4l2-async.h>
 #include <media/v4l2-fwnode.h>
 
 static int v4l2_fwnode_endpoint_parse_csi_bus(struct fwnode_handle *fwnode,
@@ -339,6 +340,99 @@ void v4l2_fwnode_put_link(struct v4l2_fwnode_link *link)
 }
 EXPORT_SYMBOL_GPL(v4l2_fwnode_put_link);
 
+static int notifier_realloc(struct device *dev,
+			    struct v4l2_async_notifier *notifier,
+			    unsigned int max_subdevs)
+{
+	struct v4l2_async_subdev **subdevs;
+	unsigned int i;
+
+	if (max_subdevs <= notifier->max_subdevs)
+		return 0;
+
+	subdevs = devm_kcalloc(
+		dev, max_subdevs, sizeof(*notifier->subdevs), GFP_KERNEL);
+	if (!subdevs)
+		return -ENOMEM;
+
+	if (notifier->subdevs) {
+		for (i = 0; i < notifier->num_subdevs; i++)
+			subdevs[i] = notifier->subdevs[i];
+
+		devm_kfree(dev, notifier->subdevs);
+	}
+
+	notifier->subdevs = subdevs;
+	notifier->max_subdevs = max_subdevs;
+
+	return 0;
+}
+
+int v4l2_fwnode_endpoints_parse(
+	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))
+		return -EINVAL;
+
+	while ((fwnode = fwnode_graph_get_next_endpoint(dev_fwnode(dev),
+							fwnode)))
+		max_subdevs++;
+
+	ret = notifier_realloc(dev, notifier, max_subdevs);
+	if (ret)
+		return ret;
+
+	for (fwnode = NULL; (fwnode = fwnode_graph_get_next_endpoint(
+				     dev_fwnode(dev), fwnode)) &&
+		     !WARN_ON(notifier->num_subdevs >= notifier->max_subdevs);
+		) {
+		struct v4l2_fwnode_endpoint *vep;
+		struct v4l2_async_subdev *asd;
+
+		asd = devm_kzalloc(dev, asd_struct_size, GFP_KERNEL);
+		if (!asd) {
+			ret = -ENOMEM;
+			goto error;
+		}
+
+		notifier->subdevs[notifier->num_subdevs] = asd;
+
+		/* Ignore endpoints the parsing of which failed. */
+		vep = v4l2_fwnode_endpoint_alloc_parse(fwnode);
+		if (IS_ERR(vep))
+			continue;
+
+		ret = parse_single(dev, vep, asd);
+		v4l2_fwnode_endpoint_free(vep);
+		if (ret)
+			goto error;
+
+		asd->match.fwnode.fwnode =
+			fwnode_graph_get_remote_port_parent(fwnode);
+		if (!asd->match.fwnode.fwnode) {
+			dev_warn(dev, "bad remote port parent\n");
+			ret = -EINVAL;
+			goto error;
+		}
+
+		asd->match_type = V4L2_ASYNC_MATCH_FWNODE;
+		notifier->num_subdevs++;
+	}
+
+error:
+	fwnode_handle_put(fwnode);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(v4l2_fwnode_endpoints_parse);
+
 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 c69d8c8..067f368 100644
--- a/include/media/v4l2-async.h
+++ b/include/media/v4l2-async.h
@@ -78,7 +78,8 @@ 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 +91,7 @@ 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;
diff --git a/include/media/v4l2-fwnode.h b/include/media/v4l2-fwnode.h
index ecc1233..ff489f7 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;
 
 /**
  * struct v4l2_fwnode_bus_mipi_csi2 - MIPI CSI-2 bus data structure
@@ -101,4 +103,11 @@ int v4l2_fwnode_parse_link(struct fwnode_handle *fwnode,
 			   struct v4l2_fwnode_link *link);
 void v4l2_fwnode_put_link(struct v4l2_fwnode_link *link);
 
+int v4l2_fwnode_endpoints_parse(
+	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 */
-- 
2.1.4

Re: [PATCH 1/2] v4l: fwnode: link_frequency is an optional property

[Niklas Söderlund]

Hi Sakari,

Thanks for your patch.

On 2017-06-29 10:30:09 +0300, Sakari Ailus wrote:
> v4l2_fwnode_endpoint_alloc_parse() is intended as a replacement for
> v4l2_fwnode_endpoint_parse(). It parses the "link-frequency" property and
> if the property isn't found, it returns an error. However,
> "link-frequency" is an optional property and if it does not exist is not
> an error. Instead, the number of link frequencies is simply zero in that
> case.
> 
> Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>

Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>

> ---
>  drivers/media/v4l2-core/v4l2-fwnode.c | 30 +++++++++++++++---------------
>  1 file changed, 15 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/media/v4l2-core/v4l2-fwnode.c b/drivers/media/v4l2-core/v4l2-fwnode.c
> index 153c53c..0ec6c14 100644
> --- a/drivers/media/v4l2-core/v4l2-fwnode.c
> +++ b/drivers/media/v4l2-core/v4l2-fwnode.c
> @@ -247,23 +247,23 @@ struct v4l2_fwnode_endpoint *v4l2_fwnode_endpoint_alloc_parse(
>  
>  	rval = fwnode_property_read_u64_array(fwnode, "link-frequencies",
>  					      NULL, 0);
> -	if (rval < 0)
> -		goto out_err;
> -
> -	vep->link_frequencies =
> -		kmalloc_array(rval, sizeof(*vep->link_frequencies), GFP_KERNEL);
> -	if (!vep->link_frequencies) {
> -		rval = -ENOMEM;
> -		goto out_err;
> -	}
> +	if (rval > 0) {
> +		vep->link_frequencies =
> +			kmalloc_array(rval, sizeof(*vep->link_frequencies),
> +				      GFP_KERNEL);
> +		if (!vep->link_frequencies) {
> +			rval = -ENOMEM;
> +			goto out_err;
> +		}
>  
> -	vep->nr_of_link_frequencies = rval;
> +		vep->nr_of_link_frequencies = rval;
>  
> -	rval = fwnode_property_read_u64_array(fwnode, "link-frequencies",
> -					      vep->link_frequencies,
> -					      vep->nr_of_link_frequencies);
> -	if (rval < 0)
> -		goto out_err;
> +		rval = fwnode_property_read_u64_array(
> +			fwnode, "link-frequencies", vep->link_frequencies,
> +			vep->nr_of_link_frequencies);
> +		if (rval < 0)
> +			goto out_err;
> +	}
>  
>  	return vep;
>  
> -- 
> 2.1.4
> 
> 

-- 
Regards,
Niklas Söderlund

Re: [PATCH 2/2] v4l: fwnode: Support generic parsing of graph endpoints in V4L2

[Niklas Söderlund]

Hi Sakari,

Thanks for your patch.

On 2017-06-29 10:30:10 +0300, 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 | 91 ++++++++++-----------------------
>  drivers/media/platform/omap3isp/isp.h |  3 --
>  drivers/media/v4l2-core/v4l2-fwnode.c | 94 +++++++++++++++++++++++++++++++++++
>  include/media/v4l2-async.h            |  4 +-
>  include/media/v4l2-fwnode.h           |  9 ++++
>  5 files changed, 132 insertions(+), 69 deletions(-)
> 
> diff --git a/drivers/media/platform/omap3isp/isp.c b/drivers/media/platform/omap3isp/isp.c
> index 9df64c1..9ccf883 100644
> --- a/drivers/media/platform/omap3isp/isp.c
> +++ b/drivers/media/platform/omap3isp/isp.c
> @@ -2008,43 +2008,42 @@ 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;
> -
> -	ret = v4l2_fwnode_endpoint_parse(fwnode, &vep);
> -	if (ret)
> -		return ret;
>  
>  	dev_dbg(dev, "parsing endpoint %s, interface %u\n",
> -		to_of_node(fwnode)->full_name, vep.base.port);
> +		to_of_node(vep->base.local_fwnode)->full_name, 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);
> +			!!(vep->bus.parallel.flags & V4L2_MBUS_DATA_ACTIVE_LOW);
>  		break;
>  
>  	case ISP_OF_PHY_CSIPHY1:
>  	case ISP_OF_PHY_CSIPHY2:
>  		/* FIXME: always assume CSI-2 for now. */
> -		switch (vep.base.port) {
> +		switch (vep->base.port) {
>  		case ISP_OF_PHY_CSIPHY1:
>  			buscfg->interface = ISP_INTERFACE_CSI2C_PHY1;
>  			break;
> @@ -2052,18 +2051,19 @@ static int isp_fwnode_parse(struct device *dev, struct fwnode_handle *fwnode,
>  			buscfg->interface = ISP_INTERFACE_CSI2A_PHY2;
>  			break;
>  		}
> -		buscfg->bus.csi2.lanecfg.clk.pos = vep.bus.mipi_csi2.clock_lane;
> +		buscfg->bus.csi2.lanecfg.clk.pos =
> +			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);
>  
>  		for (i = 0; i < ISP_CSIPHY2_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,
>  				buscfg->bus.csi2.lanecfg.data[i].pos);
> @@ -2079,55 +2079,14 @@ static int isp_fwnode_parse(struct device *dev, struct fwnode_handle *fwnode,
>  
>  	default:
>  		dev_warn(dev, "%s: invalid interface %u\n",
> -			 to_of_node(fwnode)->full_name, vep.base.port);
> +			 to_of_node(vep->base.local_fwnode)->full_name,
> +			 vep->base.port);
>  		break;
>  	}
>  
>  	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;
> -
> -		notifier->subdevs[notifier->num_subdevs] = &isd->asd;
> -
> -		if (isp_fwnode_parse(dev, fwnode, isd))
> -			goto error;
> -
> -		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_bound(struct v4l2_async_notifier *async,
>  				     struct v4l2_subdev *subdev,
>  				     struct v4l2_async_subdev *asd)
> @@ -2210,7 +2169,9 @@ static int isp_probe(struct platform_device *pdev)
>  	if (ret)
>  		return ret;
>  
> -	ret = isp_fwnodes_parse(&pdev->dev, &isp->notifier);
> +	ret = v4l2_fwnode_endpoints_parse(
> +		&pdev->dev, &isp->notifier, sizeof(struct isp_async_subdev),
> +		isp_fwnode_parse);
>  	if (ret < 0)
>  		return ret;
>  
> diff --git a/drivers/media/platform/omap3isp/isp.h b/drivers/media/platform/omap3isp/isp.h
> index 2f2ae60..a852c11 100644
> --- a/drivers/media/platform/omap3isp/isp.h
> +++ b/drivers/media/platform/omap3isp/isp.h
> @@ -220,9 +220,6 @@ 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 {
> diff --git a/drivers/media/v4l2-core/v4l2-fwnode.c b/drivers/media/v4l2-core/v4l2-fwnode.c
> index 0ec6c14..b35d525 100644
> --- a/drivers/media/v4l2-core/v4l2-fwnode.c
> +++ b/drivers/media/v4l2-core/v4l2-fwnode.c
> @@ -26,6 +26,7 @@
>  #include <linux/string.h>
>  #include <linux/types.h>
>  
> +#include <media/v4l2-async.h>
>  #include <media/v4l2-fwnode.h>
>  
>  static int v4l2_fwnode_endpoint_parse_csi_bus(struct fwnode_handle *fwnode,
> @@ -339,6 +340,99 @@ void v4l2_fwnode_put_link(struct v4l2_fwnode_link *link)
>  }
>  EXPORT_SYMBOL_GPL(v4l2_fwnode_put_link);
>  
> +static int notifier_realloc(struct device *dev,
> +			    struct v4l2_async_notifier *notifier,
> +			    unsigned int max_subdevs)
> +{
> +	struct v4l2_async_subdev **subdevs;
> +	unsigned int i;
> +
> +	if (max_subdevs <= notifier->max_subdevs)
> +		return 0;
> +
> +	subdevs = devm_kcalloc(
> +		dev, max_subdevs, sizeof(*notifier->subdevs), GFP_KERNEL);
> +	if (!subdevs)
> +		return -ENOMEM;
> +
> +	if (notifier->subdevs) {
> +		for (i = 0; i < notifier->num_subdevs; i++)
> +			subdevs[i] = notifier->subdevs[i];
> +
> +		devm_kfree(dev, notifier->subdevs);
> +	}
> +
> +	notifier->subdevs = subdevs;
> +	notifier->max_subdevs = max_subdevs;
> +
> +	return 0;
> +}
> +
> +int v4l2_fwnode_endpoints_parse(
> +	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))
> +		return -EINVAL;
> +
> +	while ((fwnode = fwnode_graph_get_next_endpoint(dev_fwnode(dev),
> +							fwnode)))
> +		max_subdevs++;
> +
> +	ret = notifier_realloc(dev, notifier, max_subdevs);
> +	if (ret)
> +		return ret;
> +
> +	for (fwnode = NULL; (fwnode = fwnode_graph_get_next_endpoint(
> +				     dev_fwnode(dev), fwnode)) &&
> +		     !WARN_ON(notifier->num_subdevs >= notifier->max_subdevs);
> +		) {
> +		struct v4l2_fwnode_endpoint *vep;
> +		struct v4l2_async_subdev *asd;
> +
> +		asd = devm_kzalloc(dev, asd_struct_size, GFP_KERNEL);
> +		if (!asd) {
> +			ret = -ENOMEM;
> +			goto error;
> +		}
> +
> +		notifier->subdevs[notifier->num_subdevs] = asd;
> +
> +		/* Ignore endpoints the parsing of which failed. */
> +		vep = v4l2_fwnode_endpoint_alloc_parse(fwnode);
> +		if (IS_ERR(vep))
> +			continue;
> +
> +		ret = parse_single(dev, vep, asd);
> +		v4l2_fwnode_endpoint_free(vep);
> +		if (ret)
> +			goto error;

First off I think this is a good step in the right direction to create 
core functions for this task.

However while reading this I got to think about a use-case I have with 
the Renesas R-Car VIN and CSI-2 drivers where I would not be able to use 
this helper. I have previously posted a patch-set to introduce 
incremental async, see [1]. If that gets picked-up not only the video 
device driver can have use of this helper but subdevices drivers.  As 
the subdevice driver would also need to pars its DT node to search for 
subdevices to add to it's own subnotifier. In this case this helper wont 
suffice, I think.

Since the subdevice DT node will contain endpoints pointing to both the 
subdevice which the incremental async notifier would like to find and 
endpoints pointing back to the root video device node it self.

In my use-case for Renesas R-Car Gen3 VIN and CSI-2 DT (not yet accepted 
upstream) I have solved this by having the CSI-2 DT node having two port 
nodes, port0 and port1. In port0 endpoints describing the 'upstream' 
video source from the CSI-2 point of view are defined (these should be 
added to the subnotifier). In port1 endpoints describing connections 
back to the VIN video devices are described. Currently the CSI-2 driver 
simply only looks for endpoints in the port0 node to add to its 
subnotifier, and I don't think this would be possible with this helper?

Perhaps this patch can be modified so that en error code from the 
callback parse_single() could be taken in to account when making the 
decision if the parsed endpoint should be added to the notifiers list of 
subdevices?

> +
> +		asd->match.fwnode.fwnode =
> +			fwnode_graph_get_remote_port_parent(fwnode);
> +		if (!asd->match.fwnode.fwnode) {
> +			dev_warn(dev, "bad remote port parent\n");
> +			ret = -EINVAL;
> +			goto error;
> +		}
> +
> +		asd->match_type = V4L2_ASYNC_MATCH_FWNODE;
> +		notifier->num_subdevs++;
> +	}
> +
> +error:
> +	fwnode_handle_put(fwnode);
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(v4l2_fwnode_endpoints_parse);
> +
>  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 c69d8c8..067f368 100644
> --- a/include/media/v4l2-async.h
> +++ b/include/media/v4l2-async.h
> @@ -78,7 +78,8 @@ 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 +91,7 @@ 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;
> diff --git a/include/media/v4l2-fwnode.h b/include/media/v4l2-fwnode.h
> index ecc1233..ff489f7 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;
>  
>  /**
>   * struct v4l2_fwnode_bus_mipi_csi2 - MIPI CSI-2 bus data structure
> @@ -101,4 +103,11 @@ int v4l2_fwnode_parse_link(struct fwnode_handle *fwnode,
>  			   struct v4l2_fwnode_link *link);
>  void v4l2_fwnode_put_link(struct v4l2_fwnode_link *link);
>  
> +int v4l2_fwnode_endpoints_parse(
> +	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 */
> -- 
> 2.1.4
> 
> 

-- 
Regards,
Niklas Söderlund

Re: [PATCH 2/2] v4l: fwnode: Support generic parsing of graph endpoints in V4L2

[Niklas Söderlund]

On 2017-06-29 11:02:03 +0200, Niklas Söderlund wrote:
> Hi Sakari,
> 
> Thanks for your patch.
> 
> On 2017-06-29 10:30:10 +0300, 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 | 91 ++++++++++-----------------------
> >  drivers/media/platform/omap3isp/isp.h |  3 --
> >  drivers/media/v4l2-core/v4l2-fwnode.c | 94 +++++++++++++++++++++++++++++++++++
> >  include/media/v4l2-async.h            |  4 +-
> >  include/media/v4l2-fwnode.h           |  9 ++++
> >  5 files changed, 132 insertions(+), 69 deletions(-)
> > 
> > diff --git a/drivers/media/platform/omap3isp/isp.c b/drivers/media/platform/omap3isp/isp.c
> > index 9df64c1..9ccf883 100644
> > --- a/drivers/media/platform/omap3isp/isp.c
> > +++ b/drivers/media/platform/omap3isp/isp.c
> > @@ -2008,43 +2008,42 @@ 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;
> > -
> > -	ret = v4l2_fwnode_endpoint_parse(fwnode, &vep);
> > -	if (ret)
> > -		return ret;
> >  
> >  	dev_dbg(dev, "parsing endpoint %s, interface %u\n",
> > -		to_of_node(fwnode)->full_name, vep.base.port);
> > +		to_of_node(vep->base.local_fwnode)->full_name, 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);
> > +			!!(vep->bus.parallel.flags & V4L2_MBUS_DATA_ACTIVE_LOW);
> >  		break;
> >  
> >  	case ISP_OF_PHY_CSIPHY1:
> >  	case ISP_OF_PHY_CSIPHY2:
> >  		/* FIXME: always assume CSI-2 for now. */
> > -		switch (vep.base.port) {
> > +		switch (vep->base.port) {
> >  		case ISP_OF_PHY_CSIPHY1:
> >  			buscfg->interface = ISP_INTERFACE_CSI2C_PHY1;
> >  			break;
> > @@ -2052,18 +2051,19 @@ static int isp_fwnode_parse(struct device *dev, struct fwnode_handle *fwnode,
> >  			buscfg->interface = ISP_INTERFACE_CSI2A_PHY2;
> >  			break;
> >  		}
> > -		buscfg->bus.csi2.lanecfg.clk.pos = vep.bus.mipi_csi2.clock_lane;
> > +		buscfg->bus.csi2.lanecfg.clk.pos =
> > +			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);
> >  
> >  		for (i = 0; i < ISP_CSIPHY2_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,
> >  				buscfg->bus.csi2.lanecfg.data[i].pos);
> > @@ -2079,55 +2079,14 @@ static int isp_fwnode_parse(struct device *dev, struct fwnode_handle *fwnode,
> >  
> >  	default:
> >  		dev_warn(dev, "%s: invalid interface %u\n",
> > -			 to_of_node(fwnode)->full_name, vep.base.port);
> > +			 to_of_node(vep->base.local_fwnode)->full_name,
> > +			 vep->base.port);
> >  		break;
> >  	}
> >  
> >  	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;
> > -
> > -		notifier->subdevs[notifier->num_subdevs] = &isd->asd;
> > -
> > -		if (isp_fwnode_parse(dev, fwnode, isd))
> > -			goto error;
> > -
> > -		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_bound(struct v4l2_async_notifier *async,
> >  				     struct v4l2_subdev *subdev,
> >  				     struct v4l2_async_subdev *asd)
> > @@ -2210,7 +2169,9 @@ static int isp_probe(struct platform_device *pdev)
> >  	if (ret)
> >  		return ret;
> >  
> > -	ret = isp_fwnodes_parse(&pdev->dev, &isp->notifier);
> > +	ret = v4l2_fwnode_endpoints_parse(
> > +		&pdev->dev, &isp->notifier, sizeof(struct isp_async_subdev),
> > +		isp_fwnode_parse);
> >  	if (ret < 0)
> >  		return ret;
> >  
> > diff --git a/drivers/media/platform/omap3isp/isp.h b/drivers/media/platform/omap3isp/isp.h
> > index 2f2ae60..a852c11 100644
> > --- a/drivers/media/platform/omap3isp/isp.h
> > +++ b/drivers/media/platform/omap3isp/isp.h
> > @@ -220,9 +220,6 @@ 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 {
> > diff --git a/drivers/media/v4l2-core/v4l2-fwnode.c b/drivers/media/v4l2-core/v4l2-fwnode.c
> > index 0ec6c14..b35d525 100644
> > --- a/drivers/media/v4l2-core/v4l2-fwnode.c
> > +++ b/drivers/media/v4l2-core/v4l2-fwnode.c
> > @@ -26,6 +26,7 @@
> >  #include <linux/string.h>
> >  #include <linux/types.h>
> >  
> > +#include <media/v4l2-async.h>
> >  #include <media/v4l2-fwnode.h>
> >  
> >  static int v4l2_fwnode_endpoint_parse_csi_bus(struct fwnode_handle *fwnode,
> > @@ -339,6 +340,99 @@ void v4l2_fwnode_put_link(struct v4l2_fwnode_link *link)
> >  }
> >  EXPORT_SYMBOL_GPL(v4l2_fwnode_put_link);
> >  
> > +static int notifier_realloc(struct device *dev,
> > +			    struct v4l2_async_notifier *notifier,
> > +			    unsigned int max_subdevs)
> > +{
> > +	struct v4l2_async_subdev **subdevs;
> > +	unsigned int i;
> > +
> > +	if (max_subdevs <= notifier->max_subdevs)
> > +		return 0;
> > +
> > +	subdevs = devm_kcalloc(
> > +		dev, max_subdevs, sizeof(*notifier->subdevs), GFP_KERNEL);
> > +	if (!subdevs)
> > +		return -ENOMEM;
> > +
> > +	if (notifier->subdevs) {
> > +		for (i = 0; i < notifier->num_subdevs; i++)
> > +			subdevs[i] = notifier->subdevs[i];
> > +
> > +		devm_kfree(dev, notifier->subdevs);
> > +	}
> > +
> > +	notifier->subdevs = subdevs;
> > +	notifier->max_subdevs = max_subdevs;
> > +
> > +	return 0;
> > +}
> > +
> > +int v4l2_fwnode_endpoints_parse(
> > +	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))
> > +		return -EINVAL;
> > +
> > +	while ((fwnode = fwnode_graph_get_next_endpoint(dev_fwnode(dev),
> > +							fwnode)))
> > +		max_subdevs++;
> > +
> > +	ret = notifier_realloc(dev, notifier, max_subdevs);
> > +	if (ret)
> > +		return ret;
> > +
> > +	for (fwnode = NULL; (fwnode = fwnode_graph_get_next_endpoint(
> > +				     dev_fwnode(dev), fwnode)) &&
> > +		     !WARN_ON(notifier->num_subdevs >= notifier->max_subdevs);
> > +		) {
> > +		struct v4l2_fwnode_endpoint *vep;
> > +		struct v4l2_async_subdev *asd;
> > +
> > +		asd = devm_kzalloc(dev, asd_struct_size, GFP_KERNEL);
> > +		if (!asd) {
> > +			ret = -ENOMEM;
> > +			goto error;
> > +		}
> > +
> > +		notifier->subdevs[notifier->num_subdevs] = asd;
> > +
> > +		/* Ignore endpoints the parsing of which failed. */
> > +		vep = v4l2_fwnode_endpoint_alloc_parse(fwnode);
> > +		if (IS_ERR(vep))
> > +			continue;
> > +
> > +		ret = parse_single(dev, vep, asd);
> > +		v4l2_fwnode_endpoint_free(vep);
> > +		if (ret)
> > +			goto error;
> 
> First off I think this is a good step in the right direction to create 
> core functions for this task.
> 
> However while reading this I got to think about a use-case I have with 
> the Renesas R-Car VIN and CSI-2 drivers where I would not be able to use 
> this helper. I have previously posted a patch-set to introduce 
> incremental async, see [1]. If that gets picked-up not only the video 
> device driver can have use of this helper but subdevices drivers.  As 
> the subdevice driver would also need to pars its DT node to search for 
> subdevices to add to it's own subnotifier. In this case this helper wont 
> suffice, I think.
> 
> Since the subdevice DT node will contain endpoints pointing to both the 
> subdevice which the incremental async notifier would like to find and 
> endpoints pointing back to the root video device node it self.
> 
> In my use-case for Renesas R-Car Gen3 VIN and CSI-2 DT (not yet accepted 
> upstream) I have solved this by having the CSI-2 DT node having two port 
> nodes, port0 and port1. In port0 endpoints describing the 'upstream' 
> video source from the CSI-2 point of view are defined (these should be 
> added to the subnotifier). In port1 endpoints describing connections 
> back to the VIN video devices are described. Currently the CSI-2 driver 
> simply only looks for endpoints in the port0 node to add to its 
> subnotifier, and I don't think this would be possible with this helper?
> 
> Perhaps this patch can be modified so that en error code from the 
> callback parse_single() could be taken in to account when making the 
> decision if the parsed endpoint should be added to the notifiers list of 
> subdevices?

Wops, I forgot.

1. https://www.spinics.net/lists/linux-media/msg116906.html

> 
> > +
> > +		asd->match.fwnode.fwnode =
> > +			fwnode_graph_get_remote_port_parent(fwnode);
> > +		if (!asd->match.fwnode.fwnode) {
> > +			dev_warn(dev, "bad remote port parent\n");
> > +			ret = -EINVAL;
> > +			goto error;
> > +		}
> > +
> > +		asd->match_type = V4L2_ASYNC_MATCH_FWNODE;
> > +		notifier->num_subdevs++;
> > +	}
> > +
> > +error:
> > +	fwnode_handle_put(fwnode);
> > +	return ret;
> > +}
> > +EXPORT_SYMBOL_GPL(v4l2_fwnode_endpoints_parse);
> > +
> >  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 c69d8c8..067f368 100644
> > --- a/include/media/v4l2-async.h
> > +++ b/include/media/v4l2-async.h
> > @@ -78,7 +78,8 @@ 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 +91,7 @@ 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;
> > diff --git a/include/media/v4l2-fwnode.h b/include/media/v4l2-fwnode.h
> > index ecc1233..ff489f7 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;
> >  
> >  /**
> >   * struct v4l2_fwnode_bus_mipi_csi2 - MIPI CSI-2 bus data structure
> > @@ -101,4 +103,11 @@ int v4l2_fwnode_parse_link(struct fwnode_handle *fwnode,
> >  			   struct v4l2_fwnode_link *link);
> >  void v4l2_fwnode_put_link(struct v4l2_fwnode_link *link);
> >  
> > +int v4l2_fwnode_endpoints_parse(
> > +	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 */
> > -- 
> > 2.1.4
> > 
> > 
> 
> -- 
> Regards,
> Niklas Söderlund

-- 
Regards,
Niklas Söderlund

Re: [PATCH 2/2] v4l: fwnode: Support generic parsing of graph endpoints in V4L2

[Sakari Ailus]

On Thu, Jun 29, 2017 at 11:02:03AM +0200, Niklas Söderlund wrote:
> Hi Sakari,
> 
> Thanks for your patch.
> 
> On 2017-06-29 10:30:10 +0300, 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 | 91 ++++++++++-----------------------
> >  drivers/media/platform/omap3isp/isp.h |  3 --
> >  drivers/media/v4l2-core/v4l2-fwnode.c | 94 +++++++++++++++++++++++++++++++++++
> >  include/media/v4l2-async.h            |  4 +-
> >  include/media/v4l2-fwnode.h           |  9 ++++
> >  5 files changed, 132 insertions(+), 69 deletions(-)
> > 
> > diff --git a/drivers/media/platform/omap3isp/isp.c b/drivers/media/platform/omap3isp/isp.c
> > index 9df64c1..9ccf883 100644
> > --- a/drivers/media/platform/omap3isp/isp.c
> > +++ b/drivers/media/platform/omap3isp/isp.c
> > @@ -2008,43 +2008,42 @@ 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;
> > -
> > -	ret = v4l2_fwnode_endpoint_parse(fwnode, &vep);
> > -	if (ret)
> > -		return ret;
> >  
> >  	dev_dbg(dev, "parsing endpoint %s, interface %u\n",
> > -		to_of_node(fwnode)->full_name, vep.base.port);
> > +		to_of_node(vep->base.local_fwnode)->full_name, 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);
> > +			!!(vep->bus.parallel.flags & V4L2_MBUS_DATA_ACTIVE_LOW);
> >  		break;
> >  
> >  	case ISP_OF_PHY_CSIPHY1:
> >  	case ISP_OF_PHY_CSIPHY2:
> >  		/* FIXME: always assume CSI-2 for now. */
> > -		switch (vep.base.port) {
> > +		switch (vep->base.port) {
> >  		case ISP_OF_PHY_CSIPHY1:
> >  			buscfg->interface = ISP_INTERFACE_CSI2C_PHY1;
> >  			break;
> > @@ -2052,18 +2051,19 @@ static int isp_fwnode_parse(struct device *dev, struct fwnode_handle *fwnode,
> >  			buscfg->interface = ISP_INTERFACE_CSI2A_PHY2;
> >  			break;
> >  		}
> > -		buscfg->bus.csi2.lanecfg.clk.pos = vep.bus.mipi_csi2.clock_lane;
> > +		buscfg->bus.csi2.lanecfg.clk.pos =
> > +			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);
> >  
> >  		for (i = 0; i < ISP_CSIPHY2_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,
> >  				buscfg->bus.csi2.lanecfg.data[i].pos);
> > @@ -2079,55 +2079,14 @@ static int isp_fwnode_parse(struct device *dev, struct fwnode_handle *fwnode,
> >  
> >  	default:
> >  		dev_warn(dev, "%s: invalid interface %u\n",
> > -			 to_of_node(fwnode)->full_name, vep.base.port);
> > +			 to_of_node(vep->base.local_fwnode)->full_name,
> > +			 vep->base.port);
> >  		break;
> >  	}
> >  
> >  	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;
> > -
> > -		notifier->subdevs[notifier->num_subdevs] = &isd->asd;
> > -
> > -		if (isp_fwnode_parse(dev, fwnode, isd))
> > -			goto error;
> > -
> > -		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_bound(struct v4l2_async_notifier *async,
> >  				     struct v4l2_subdev *subdev,
> >  				     struct v4l2_async_subdev *asd)
> > @@ -2210,7 +2169,9 @@ static int isp_probe(struct platform_device *pdev)
> >  	if (ret)
> >  		return ret;
> >  
> > -	ret = isp_fwnodes_parse(&pdev->dev, &isp->notifier);
> > +	ret = v4l2_fwnode_endpoints_parse(
> > +		&pdev->dev, &isp->notifier, sizeof(struct isp_async_subdev),
> > +		isp_fwnode_parse);
> >  	if (ret < 0)
> >  		return ret;
> >  
> > diff --git a/drivers/media/platform/omap3isp/isp.h b/drivers/media/platform/omap3isp/isp.h
> > index 2f2ae60..a852c11 100644
> > --- a/drivers/media/platform/omap3isp/isp.h
> > +++ b/drivers/media/platform/omap3isp/isp.h
> > @@ -220,9 +220,6 @@ 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 {
> > diff --git a/drivers/media/v4l2-core/v4l2-fwnode.c b/drivers/media/v4l2-core/v4l2-fwnode.c
> > index 0ec6c14..b35d525 100644
> > --- a/drivers/media/v4l2-core/v4l2-fwnode.c
> > +++ b/drivers/media/v4l2-core/v4l2-fwnode.c
> > @@ -26,6 +26,7 @@
> >  #include <linux/string.h>
> >  #include <linux/types.h>
> >  
> > +#include <media/v4l2-async.h>
> >  #include <media/v4l2-fwnode.h>
> >  
> >  static int v4l2_fwnode_endpoint_parse_csi_bus(struct fwnode_handle *fwnode,
> > @@ -339,6 +340,99 @@ void v4l2_fwnode_put_link(struct v4l2_fwnode_link *link)
> >  }
> >  EXPORT_SYMBOL_GPL(v4l2_fwnode_put_link);
> >  
> > +static int notifier_realloc(struct device *dev,
> > +			    struct v4l2_async_notifier *notifier,
> > +			    unsigned int max_subdevs)
> > +{
> > +	struct v4l2_async_subdev **subdevs;
> > +	unsigned int i;
> > +
> > +	if (max_subdevs <= notifier->max_subdevs)
> > +		return 0;
> > +
> > +	subdevs = devm_kcalloc(
> > +		dev, max_subdevs, sizeof(*notifier->subdevs), GFP_KERNEL);
> > +	if (!subdevs)
> > +		return -ENOMEM;
> > +
> > +	if (notifier->subdevs) {
> > +		for (i = 0; i < notifier->num_subdevs; i++)
> > +			subdevs[i] = notifier->subdevs[i];
> > +
> > +		devm_kfree(dev, notifier->subdevs);
> > +	}
> > +
> > +	notifier->subdevs = subdevs;
> > +	notifier->max_subdevs = max_subdevs;
> > +
> > +	return 0;
> > +}
> > +
> > +int v4l2_fwnode_endpoints_parse(
> > +	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))
> > +		return -EINVAL;
> > +
> > +	while ((fwnode = fwnode_graph_get_next_endpoint(dev_fwnode(dev),
> > +							fwnode)))
> > +		max_subdevs++;
> > +
> > +	ret = notifier_realloc(dev, notifier, max_subdevs);
> > +	if (ret)
> > +		return ret;
> > +
> > +	for (fwnode = NULL; (fwnode = fwnode_graph_get_next_endpoint(
> > +				     dev_fwnode(dev), fwnode)) &&
> > +		     !WARN_ON(notifier->num_subdevs >= notifier->max_subdevs);
> > +		) {
> > +		struct v4l2_fwnode_endpoint *vep;
> > +		struct v4l2_async_subdev *asd;
> > +
> > +		asd = devm_kzalloc(dev, asd_struct_size, GFP_KERNEL);
> > +		if (!asd) {
> > +			ret = -ENOMEM;
> > +			goto error;
> > +		}
> > +
> > +		notifier->subdevs[notifier->num_subdevs] = asd;
> > +
> > +		/* Ignore endpoints the parsing of which failed. */
> > +		vep = v4l2_fwnode_endpoint_alloc_parse(fwnode);
> > +		if (IS_ERR(vep))
> > +			continue;
> > +
> > +		ret = parse_single(dev, vep, asd);
> > +		v4l2_fwnode_endpoint_free(vep);
> > +		if (ret)
> > +			goto error;
> 
> First off I think this is a good step in the right direction to create 
> core functions for this task.
> 
> However while reading this I got to think about a use-case I have with 
> the Renesas R-Car VIN and CSI-2 drivers where I would not be able to use 
> this helper. I have previously posted a patch-set to introduce 
> incremental async, see [1]. If that gets picked-up not only the video 
> device driver can have use of this helper but subdevices drivers.  As 
> the subdevice driver would also need to pars its DT node to search for 
> subdevices to add to it's own subnotifier. In this case this helper wont 
> suffice, I think.
> 
> Since the subdevice DT node will contain endpoints pointing to both the 
> subdevice which the incremental async notifier would like to find and 
> endpoints pointing back to the root video device node it self.
> 
> In my use-case for Renesas R-Car Gen3 VIN and CSI-2 DT (not yet accepted 
> upstream) I have solved this by having the CSI-2 DT node having two port 
> nodes, port0 and port1. In port0 endpoints describing the 'upstream' 
> video source from the CSI-2 point of view are defined (these should be 
> added to the subnotifier). In port1 endpoints describing connections 
> back to the VIN video devices are described. Currently the CSI-2 driver 
> simply only looks for endpoints in the port0 node to add to its 
> subnotifier, and I don't think this would be possible with this helper?

What we could also do is to add a variant of this that parses the endpoints
by the port / endpoint IDs. Then you don't need to have a cumbersome way to
skip parsing of some ports --- you would have allocated the memory and
parsed the port for nothing by the time you call the callback anyway.

That would seem to be a better approach in general. I remember Rob was
pushing this for DRM as it greatly simplified driver code there. But then
the DT bindings have to be written accordingly: in current bindings the
endpoint IDs are mostly undefined.

We may still need to take extra measures to support cases where there are
multiple links between two sub-devices.

What do you think?

Cc Rob + devicetree list as well.

> 
> Perhaps this patch can be modified so that en error code from the 
> callback parse_single() could be taken in to account when making the 
> decision if the parsed endpoint should be added to the notifiers list of 
> subdevices?
> 
> > +
> > +		asd->match.fwnode.fwnode =
> > +			fwnode_graph_get_remote_port_parent(fwnode);
> > +		if (!asd->match.fwnode.fwnode) {
> > +			dev_warn(dev, "bad remote port parent\n");
> > +			ret = -EINVAL;
> > +			goto error;
> > +		}
> > +
> > +		asd->match_type = V4L2_ASYNC_MATCH_FWNODE;
> > +		notifier->num_subdevs++;
> > +	}
> > +
> > +error:
> > +	fwnode_handle_put(fwnode);
> > +	return ret;
> > +}
> > +EXPORT_SYMBOL_GPL(v4l2_fwnode_endpoints_parse);
> > +
> >  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 c69d8c8..067f368 100644
> > --- a/include/media/v4l2-async.h
> > +++ b/include/media/v4l2-async.h
> > @@ -78,7 +78,8 @@ 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 +91,7 @@ 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;
> > diff --git a/include/media/v4l2-fwnode.h b/include/media/v4l2-fwnode.h
> > index ecc1233..ff489f7 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;
> >  
> >  /**
> >   * struct v4l2_fwnode_bus_mipi_csi2 - MIPI CSI-2 bus data structure
> > @@ -101,4 +103,11 @@ int v4l2_fwnode_parse_link(struct fwnode_handle *fwnode,
> >  			   struct v4l2_fwnode_link *link);
> >  void v4l2_fwnode_put_link(struct v4l2_fwnode_link *link);
> >  
> > +int v4l2_fwnode_endpoints_parse(
> > +	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 */
> > -- 
> > 2.1.4
> > 
> > 
> 
> -- 
> Regards,
> Niklas Söderlund

-- 
Sakari Ailus
e-mail: sakari.ailus-X3B1VOXEql0@public.gmane.org	XMPP: sailus-PCDdDYkjdNMDXYZnReoRVg@public.gmane.org
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Re: [PATCH 2/2] v4l: fwnode: Support generic parsing of graph endpoints in V4L2

[Sakari Ailus]

On Thu, Jun 29, 2017 at 11:02:03AM +0200, Niklas Söderlund wrote:
> Hi Sakari,
> 
> Thanks for your patch.
> 
> On 2017-06-29 10:30:10 +0300, 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 | 91 ++++++++++-----------------------
> >  drivers/media/platform/omap3isp/isp.h |  3 --
> >  drivers/media/v4l2-core/v4l2-fwnode.c | 94 +++++++++++++++++++++++++++++++++++
> >  include/media/v4l2-async.h            |  4 +-
> >  include/media/v4l2-fwnode.h           |  9 ++++
> >  5 files changed, 132 insertions(+), 69 deletions(-)
> > 
> > diff --git a/drivers/media/platform/omap3isp/isp.c b/drivers/media/platform/omap3isp/isp.c
> > index 9df64c1..9ccf883 100644
> > --- a/drivers/media/platform/omap3isp/isp.c
> > +++ b/drivers/media/platform/omap3isp/isp.c
> > @@ -2008,43 +2008,42 @@ 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;
> > -
> > -	ret = v4l2_fwnode_endpoint_parse(fwnode, &vep);
> > -	if (ret)
> > -		return ret;
> >  
> >  	dev_dbg(dev, "parsing endpoint %s, interface %u\n",
> > -		to_of_node(fwnode)->full_name, vep.base.port);
> > +		to_of_node(vep->base.local_fwnode)->full_name, 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);
> > +			!!(vep->bus.parallel.flags & V4L2_MBUS_DATA_ACTIVE_LOW);
> >  		break;
> >  
> >  	case ISP_OF_PHY_CSIPHY1:
> >  	case ISP_OF_PHY_CSIPHY2:
> >  		/* FIXME: always assume CSI-2 for now. */
> > -		switch (vep.base.port) {
> > +		switch (vep->base.port) {
> >  		case ISP_OF_PHY_CSIPHY1:
> >  			buscfg->interface = ISP_INTERFACE_CSI2C_PHY1;
> >  			break;
> > @@ -2052,18 +2051,19 @@ static int isp_fwnode_parse(struct device *dev, struct fwnode_handle *fwnode,
> >  			buscfg->interface = ISP_INTERFACE_CSI2A_PHY2;
> >  			break;
> >  		}
> > -		buscfg->bus.csi2.lanecfg.clk.pos = vep.bus.mipi_csi2.clock_lane;
> > +		buscfg->bus.csi2.lanecfg.clk.pos =
> > +			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);
> >  
> >  		for (i = 0; i < ISP_CSIPHY2_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,
> >  				buscfg->bus.csi2.lanecfg.data[i].pos);
> > @@ -2079,55 +2079,14 @@ static int isp_fwnode_parse(struct device *dev, struct fwnode_handle *fwnode,
> >  
> >  	default:
> >  		dev_warn(dev, "%s: invalid interface %u\n",
> > -			 to_of_node(fwnode)->full_name, vep.base.port);
> > +			 to_of_node(vep->base.local_fwnode)->full_name,
> > +			 vep->base.port);
> >  		break;
> >  	}
> >  
> >  	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;
> > -
> > -		notifier->subdevs[notifier->num_subdevs] = &isd->asd;
> > -
> > -		if (isp_fwnode_parse(dev, fwnode, isd))
> > -			goto error;
> > -
> > -		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_bound(struct v4l2_async_notifier *async,
> >  				     struct v4l2_subdev *subdev,
> >  				     struct v4l2_async_subdev *asd)
> > @@ -2210,7 +2169,9 @@ static int isp_probe(struct platform_device *pdev)
> >  	if (ret)
> >  		return ret;
> >  
> > -	ret = isp_fwnodes_parse(&pdev->dev, &isp->notifier);
> > +	ret = v4l2_fwnode_endpoints_parse(
> > +		&pdev->dev, &isp->notifier, sizeof(struct isp_async_subdev),
> > +		isp_fwnode_parse);
> >  	if (ret < 0)
> >  		return ret;
> >  
> > diff --git a/drivers/media/platform/omap3isp/isp.h b/drivers/media/platform/omap3isp/isp.h
> > index 2f2ae60..a852c11 100644
> > --- a/drivers/media/platform/omap3isp/isp.h
> > +++ b/drivers/media/platform/omap3isp/isp.h
> > @@ -220,9 +220,6 @@ 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 {
> > diff --git a/drivers/media/v4l2-core/v4l2-fwnode.c b/drivers/media/v4l2-core/v4l2-fwnode.c
> > index 0ec6c14..b35d525 100644
> > --- a/drivers/media/v4l2-core/v4l2-fwnode.c
> > +++ b/drivers/media/v4l2-core/v4l2-fwnode.c
> > @@ -26,6 +26,7 @@
> >  #include <linux/string.h>
> >  #include <linux/types.h>
> >  
> > +#include <media/v4l2-async.h>
> >  #include <media/v4l2-fwnode.h>
> >  
> >  static int v4l2_fwnode_endpoint_parse_csi_bus(struct fwnode_handle *fwnode,
> > @@ -339,6 +340,99 @@ void v4l2_fwnode_put_link(struct v4l2_fwnode_link *link)
> >  }
> >  EXPORT_SYMBOL_GPL(v4l2_fwnode_put_link);
> >  
> > +static int notifier_realloc(struct device *dev,
> > +			    struct v4l2_async_notifier *notifier,
> > +			    unsigned int max_subdevs)
> > +{
> > +	struct v4l2_async_subdev **subdevs;
> > +	unsigned int i;
> > +
> > +	if (max_subdevs <= notifier->max_subdevs)
> > +		return 0;
> > +
> > +	subdevs = devm_kcalloc(
> > +		dev, max_subdevs, sizeof(*notifier->subdevs), GFP_KERNEL);
> > +	if (!subdevs)
> > +		return -ENOMEM;
> > +
> > +	if (notifier->subdevs) {
> > +		for (i = 0; i < notifier->num_subdevs; i++)
> > +			subdevs[i] = notifier->subdevs[i];
> > +
> > +		devm_kfree(dev, notifier->subdevs);
> > +	}
> > +
> > +	notifier->subdevs = subdevs;
> > +	notifier->max_subdevs = max_subdevs;
> > +
> > +	return 0;
> > +}
> > +
> > +int v4l2_fwnode_endpoints_parse(
> > +	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))
> > +		return -EINVAL;
> > +
> > +	while ((fwnode = fwnode_graph_get_next_endpoint(dev_fwnode(dev),
> > +							fwnode)))
> > +		max_subdevs++;
> > +
> > +	ret = notifier_realloc(dev, notifier, max_subdevs);
> > +	if (ret)
> > +		return ret;
> > +
> > +	for (fwnode = NULL; (fwnode = fwnode_graph_get_next_endpoint(
> > +				     dev_fwnode(dev), fwnode)) &&
> > +		     !WARN_ON(notifier->num_subdevs >= notifier->max_subdevs);
> > +		) {
> > +		struct v4l2_fwnode_endpoint *vep;
> > +		struct v4l2_async_subdev *asd;
> > +
> > +		asd = devm_kzalloc(dev, asd_struct_size, GFP_KERNEL);
> > +		if (!asd) {
> > +			ret = -ENOMEM;
> > +			goto error;
> > +		}
> > +
> > +		notifier->subdevs[notifier->num_subdevs] = asd;
> > +
> > +		/* Ignore endpoints the parsing of which failed. */
> > +		vep = v4l2_fwnode_endpoint_alloc_parse(fwnode);
> > +		if (IS_ERR(vep))
> > +			continue;
> > +
> > +		ret = parse_single(dev, vep, asd);
> > +		v4l2_fwnode_endpoint_free(vep);
> > +		if (ret)
> > +			goto error;
> 
> First off I think this is a good step in the right direction to create 
> core functions for this task.
> 
> However while reading this I got to think about a use-case I have with 
> the Renesas R-Car VIN and CSI-2 drivers where I would not be able to use 
> this helper. I have previously posted a patch-set to introduce 
> incremental async, see [1]. If that gets picked-up not only the video 
> device driver can have use of this helper but subdevices drivers.  As 
> the subdevice driver would also need to pars its DT node to search for 
> subdevices to add to it's own subnotifier. In this case this helper wont 
> suffice, I think.
> 
> Since the subdevice DT node will contain endpoints pointing to both the 
> subdevice which the incremental async notifier would like to find and 
> endpoints pointing back to the root video device node it self.
> 
> In my use-case for Renesas R-Car Gen3 VIN and CSI-2 DT (not yet accepted 
> upstream) I have solved this by having the CSI-2 DT node having two port 
> nodes, port0 and port1. In port0 endpoints describing the 'upstream' 
> video source from the CSI-2 point of view are defined (these should be 
> added to the subnotifier). In port1 endpoints describing connections 
> back to the VIN video devices are described. Currently the CSI-2 driver 
> simply only looks for endpoints in the port0 node to add to its 
> subnotifier, and I don't think this would be possible with this helper?

What we could also do is to add a variant of this that parses the endpoints
by the port / endpoint IDs. Then you don't need to have a cumbersome way to
skip parsing of some ports --- you would have allocated the memory and
parsed the port for nothing by the time you call the callback anyway.

That would seem to be a better approach in general. I remember Rob was
pushing this for DRM as it greatly simplified driver code there. But then
the DT bindings have to be written accordingly: in current bindings the
endpoint IDs are mostly undefined.

We may still need to take extra measures to support cases where there are
multiple links between two sub-devices.

What do you think?

Cc Rob + devicetree list as well.

> 
> Perhaps this patch can be modified so that en error code from the 
> callback parse_single() could be taken in to account when making the 
> decision if the parsed endpoint should be added to the notifiers list of 
> subdevices?
> 
> > +
> > +		asd->match.fwnode.fwnode =
> > +			fwnode_graph_get_remote_port_parent(fwnode);
> > +		if (!asd->match.fwnode.fwnode) {
> > +			dev_warn(dev, "bad remote port parent\n");
> > +			ret = -EINVAL;
> > +			goto error;
> > +		}
> > +
> > +		asd->match_type = V4L2_ASYNC_MATCH_FWNODE;
> > +		notifier->num_subdevs++;
> > +	}
> > +
> > +error:
> > +	fwnode_handle_put(fwnode);
> > +	return ret;
> > +}
> > +EXPORT_SYMBOL_GPL(v4l2_fwnode_endpoints_parse);
> > +
> >  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 c69d8c8..067f368 100644
> > --- a/include/media/v4l2-async.h
> > +++ b/include/media/v4l2-async.h
> > @@ -78,7 +78,8 @@ 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 +91,7 @@ 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;
> > diff --git a/include/media/v4l2-fwnode.h b/include/media/v4l2-fwnode.h
> > index ecc1233..ff489f7 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;
> >  
> >  /**
> >   * struct v4l2_fwnode_bus_mipi_csi2 - MIPI CSI-2 bus data structure
> > @@ -101,4 +103,11 @@ int v4l2_fwnode_parse_link(struct fwnode_handle *fwnode,
> >  			   struct v4l2_fwnode_link *link);
> >  void v4l2_fwnode_put_link(struct v4l2_fwnode_link *link);
> >  
> > +int v4l2_fwnode_endpoints_parse(
> > +	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 */
> > -- 
> > 2.1.4
> > 
> > 
> 
> -- 
> Regards,
> Niklas Söderlund

-- 
Sakari Ailus
e-mail: sakari.ailus@iki.fi	XMPP: sailus@retiisi.org.uk

Re: [PATCH 2/2] v4l: fwnode: Support generic parsing of graph endpoints in V4L2

[Niklas Söderlund]

On 2017-06-29 12:57:55 +0300, Sakari Ailus wrote:
> On Thu, Jun 29, 2017 at 11:02:03AM +0200, Niklas Söderlund wrote:
> > Hi Sakari,
> > 
> > Thanks for your patch.
> > 
> > On 2017-06-29 10:30:10 +0300, 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 | 91 ++++++++++-----------------------
> > >  drivers/media/platform/omap3isp/isp.h |  3 --
> > >  drivers/media/v4l2-core/v4l2-fwnode.c | 94 +++++++++++++++++++++++++++++++++++
> > >  include/media/v4l2-async.h            |  4 +-
> > >  include/media/v4l2-fwnode.h           |  9 ++++
> > >  5 files changed, 132 insertions(+), 69 deletions(-)
> > > 
> > > diff --git a/drivers/media/platform/omap3isp/isp.c b/drivers/media/platform/omap3isp/isp.c
> > > index 9df64c1..9ccf883 100644
> > > --- a/drivers/media/platform/omap3isp/isp.c
> > > +++ b/drivers/media/platform/omap3isp/isp.c
> > > @@ -2008,43 +2008,42 @@ 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;
> > > -
> > > -	ret = v4l2_fwnode_endpoint_parse(fwnode, &vep);
> > > -	if (ret)
> > > -		return ret;
> > >  
> > >  	dev_dbg(dev, "parsing endpoint %s, interface %u\n",
> > > -		to_of_node(fwnode)->full_name, vep.base.port);
> > > +		to_of_node(vep->base.local_fwnode)->full_name, 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);
> > > +			!!(vep->bus.parallel.flags & V4L2_MBUS_DATA_ACTIVE_LOW);
> > >  		break;
> > >  
> > >  	case ISP_OF_PHY_CSIPHY1:
> > >  	case ISP_OF_PHY_CSIPHY2:
> > >  		/* FIXME: always assume CSI-2 for now. */
> > > -		switch (vep.base.port) {
> > > +		switch (vep->base.port) {
> > >  		case ISP_OF_PHY_CSIPHY1:
> > >  			buscfg->interface = ISP_INTERFACE_CSI2C_PHY1;
> > >  			break;
> > > @@ -2052,18 +2051,19 @@ static int isp_fwnode_parse(struct device *dev, struct fwnode_handle *fwnode,
> > >  			buscfg->interface = ISP_INTERFACE_CSI2A_PHY2;
> > >  			break;
> > >  		}
> > > -		buscfg->bus.csi2.lanecfg.clk.pos = vep.bus.mipi_csi2.clock_lane;
> > > +		buscfg->bus.csi2.lanecfg.clk.pos =
> > > +			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);
> > >  
> > >  		for (i = 0; i < ISP_CSIPHY2_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,
> > >  				buscfg->bus.csi2.lanecfg.data[i].pos);
> > > @@ -2079,55 +2079,14 @@ static int isp_fwnode_parse(struct device *dev, struct fwnode_handle *fwnode,
> > >  
> > >  	default:
> > >  		dev_warn(dev, "%s: invalid interface %u\n",
> > > -			 to_of_node(fwnode)->full_name, vep.base.port);
> > > +			 to_of_node(vep->base.local_fwnode)->full_name,
> > > +			 vep->base.port);
> > >  		break;
> > >  	}
> > >  
> > >  	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;
> > > -
> > > -		notifier->subdevs[notifier->num_subdevs] = &isd->asd;
> > > -
> > > -		if (isp_fwnode_parse(dev, fwnode, isd))
> > > -			goto error;
> > > -
> > > -		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_bound(struct v4l2_async_notifier *async,
> > >  				     struct v4l2_subdev *subdev,
> > >  				     struct v4l2_async_subdev *asd)
> > > @@ -2210,7 +2169,9 @@ static int isp_probe(struct platform_device *pdev)
> > >  	if (ret)
> > >  		return ret;
> > >  
> > > -	ret = isp_fwnodes_parse(&pdev->dev, &isp->notifier);
> > > +	ret = v4l2_fwnode_endpoints_parse(
> > > +		&pdev->dev, &isp->notifier, sizeof(struct isp_async_subdev),
> > > +		isp_fwnode_parse);
> > >  	if (ret < 0)
> > >  		return ret;
> > >  
> > > diff --git a/drivers/media/platform/omap3isp/isp.h b/drivers/media/platform/omap3isp/isp.h
> > > index 2f2ae60..a852c11 100644
> > > --- a/drivers/media/platform/omap3isp/isp.h
> > > +++ b/drivers/media/platform/omap3isp/isp.h
> > > @@ -220,9 +220,6 @@ 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 {
> > > diff --git a/drivers/media/v4l2-core/v4l2-fwnode.c b/drivers/media/v4l2-core/v4l2-fwnode.c
> > > index 0ec6c14..b35d525 100644
> > > --- a/drivers/media/v4l2-core/v4l2-fwnode.c
> > > +++ b/drivers/media/v4l2-core/v4l2-fwnode.c
> > > @@ -26,6 +26,7 @@
> > >  #include <linux/string.h>
> > >  #include <linux/types.h>
> > >  
> > > +#include <media/v4l2-async.h>
> > >  #include <media/v4l2-fwnode.h>
> > >  
> > >  static int v4l2_fwnode_endpoint_parse_csi_bus(struct fwnode_handle *fwnode,
> > > @@ -339,6 +340,99 @@ void v4l2_fwnode_put_link(struct v4l2_fwnode_link *link)
> > >  }
> > >  EXPORT_SYMBOL_GPL(v4l2_fwnode_put_link);
> > >  
> > > +static int notifier_realloc(struct device *dev,
> > > +			    struct v4l2_async_notifier *notifier,
> > > +			    unsigned int max_subdevs)
> > > +{
> > > +	struct v4l2_async_subdev **subdevs;
> > > +	unsigned int i;
> > > +
> > > +	if (max_subdevs <= notifier->max_subdevs)
> > > +		return 0;
> > > +
> > > +	subdevs = devm_kcalloc(
> > > +		dev, max_subdevs, sizeof(*notifier->subdevs), GFP_KERNEL);
> > > +	if (!subdevs)
> > > +		return -ENOMEM;
> > > +
> > > +	if (notifier->subdevs) {
> > > +		for (i = 0; i < notifier->num_subdevs; i++)
> > > +			subdevs[i] = notifier->subdevs[i];
> > > +
> > > +		devm_kfree(dev, notifier->subdevs);
> > > +	}
> > > +
> > > +	notifier->subdevs = subdevs;
> > > +	notifier->max_subdevs = max_subdevs;
> > > +
> > > +	return 0;
> > > +}
> > > +
> > > +int v4l2_fwnode_endpoints_parse(
> > > +	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))
> > > +		return -EINVAL;
> > > +
> > > +	while ((fwnode = fwnode_graph_get_next_endpoint(dev_fwnode(dev),
> > > +							fwnode)))
> > > +		max_subdevs++;
> > > +
> > > +	ret = notifier_realloc(dev, notifier, max_subdevs);
> > > +	if (ret)
> > > +		return ret;
> > > +
> > > +	for (fwnode = NULL; (fwnode = fwnode_graph_get_next_endpoint(
> > > +				     dev_fwnode(dev), fwnode)) &&
> > > +		     !WARN_ON(notifier->num_subdevs >= notifier->max_subdevs);
> > > +		) {
> > > +		struct v4l2_fwnode_endpoint *vep;
> > > +		struct v4l2_async_subdev *asd;
> > > +
> > > +		asd = devm_kzalloc(dev, asd_struct_size, GFP_KERNEL);
> > > +		if (!asd) {
> > > +			ret = -ENOMEM;
> > > +			goto error;
> > > +		}
> > > +
> > > +		notifier->subdevs[notifier->num_subdevs] = asd;
> > > +
> > > +		/* Ignore endpoints the parsing of which failed. */
> > > +		vep = v4l2_fwnode_endpoint_alloc_parse(fwnode);
> > > +		if (IS_ERR(vep))
> > > +			continue;
> > > +
> > > +		ret = parse_single(dev, vep, asd);
> > > +		v4l2_fwnode_endpoint_free(vep);
> > > +		if (ret)
> > > +			goto error;
> > 
> > First off I think this is a good step in the right direction to create 
> > core functions for this task.
> > 
> > However while reading this I got to think about a use-case I have with 
> > the Renesas R-Car VIN and CSI-2 drivers where I would not be able to use 
> > this helper. I have previously posted a patch-set to introduce 
> > incremental async, see [1]. If that gets picked-up not only the video 
> > device driver can have use of this helper but subdevices drivers.  As 
> > the subdevice driver would also need to pars its DT node to search for 
> > subdevices to add to it's own subnotifier. In this case this helper wont 
> > suffice, I think.
> > 
> > Since the subdevice DT node will contain endpoints pointing to both the 
> > subdevice which the incremental async notifier would like to find and 
> > endpoints pointing back to the root video device node it self.
> > 
> > In my use-case for Renesas R-Car Gen3 VIN and CSI-2 DT (not yet accepted 
> > upstream) I have solved this by having the CSI-2 DT node having two port 
> > nodes, port0 and port1. In port0 endpoints describing the 'upstream' 
> > video source from the CSI-2 point of view are defined (these should be 
> > added to the subnotifier). In port1 endpoints describing connections 
> > back to the VIN video devices are described. Currently the CSI-2 driver 
> > simply only looks for endpoints in the port0 node to add to its 
> > subnotifier, and I don't think this would be possible with this helper?
> 
> What we could also do is to add a variant of this that parses the endpoints
> by the port / endpoint IDs. Then you don't need to have a cumbersome way to
> skip parsing of some ports --- you would have allocated the memory and
> parsed the port for nothing by the time you call the callback anyway.
> 
> That would seem to be a better approach in general. I remember Rob was
> pushing this for DRM as it greatly simplified driver code there. But then
> the DT bindings have to be written accordingly: in current bindings the
> endpoint IDs are mostly undefined.
> 
> We may still need to take extra measures to support cases where there are
> multiple links between two sub-devices.
> 
> What do you think?

A variant of this that as you suggest parses by port I think make sens.  
I'm not sure how one would go about creating a simple interface which 
would support parsing by port+endpoint IDs, but if it's possible that 
would be also be nice.

Another option is to instead of passing a struct device pass a struct 
fwnode_handle which would act as the root search path. That way one 
could pass a fwnode_handle to a specific port node and just iterate over 
all endpoints in that port. But that way the driver side implementation 
becomes more complex since it needs to lookup the fwnode_handle so I'm 
not sure I think that is the best solution.

So yes I think your suggestion of adding a variant which takes port 
and/or port+endpoint IDs into account to be the best solution.

> 
> Cc Rob + devicetree list as well.
> 
> > 
> > Perhaps this patch can be modified so that en error code from the 
> > callback parse_single() could be taken in to account when making the 
> > decision if the parsed endpoint should be added to the notifiers 
> > list of subdevices?
> > 
> > > +
> > > +		asd->match.fwnode.fwnode =
> > > +			fwnode_graph_get_remote_port_parent(fwnode);
> > > +		if (!asd->match.fwnode.fwnode) {
> > > +			dev_warn(dev, "bad remote port parent\n");
> > > +			ret = -EINVAL;
> > > +			goto error;
> > > +		}
> > > +
> > > +		asd->match_type = V4L2_ASYNC_MATCH_FWNODE;
> > > +		notifier->num_subdevs++;
> > > +	}
> > > +
> > > +error:
> > > +	fwnode_handle_put(fwnode);
> > > +	return ret;
> > > +}
> > > +EXPORT_SYMBOL_GPL(v4l2_fwnode_endpoints_parse);
> > > +
> > >  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 c69d8c8..067f368 100644
> > > --- a/include/media/v4l2-async.h
> > > +++ b/include/media/v4l2-async.h
> > > @@ -78,7 +78,8 @@ 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 +91,7 @@ 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;
> > > diff --git a/include/media/v4l2-fwnode.h b/include/media/v4l2-fwnode.h
> > > index ecc1233..ff489f7 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;
> > >  
> > >  /**
> > >   * struct v4l2_fwnode_bus_mipi_csi2 - MIPI CSI-2 bus data structure
> > > @@ -101,4 +103,11 @@ int v4l2_fwnode_parse_link(struct fwnode_handle *fwnode,
> > >  			   struct v4l2_fwnode_link *link);
> > >  void v4l2_fwnode_put_link(struct v4l2_fwnode_link *link);
> > >  
> > > +int v4l2_fwnode_endpoints_parse(
> > > +	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 */
> > > -- 
> > > 2.1.4
> > > 
> > > 
> > 
> > -- 
> > Regards,
> > Niklas Söderlund
> 
> -- 
> Sakari Ailus
> e-mail: sakari.ailus@iki.fi	XMPP: sailus@retiisi.org.uk

-- 
Regards,
Niklas Söderlund

Re: [PATCH 2/2] v4l: fwnode: Support generic parsing of graph endpoints in V4L2

[Sakari Ailus]

On Thu, Jun 29, 2017 at 12:18:44PM +0200, Niklas Söderlund wrote:
> On 2017-06-29 12:57:55 +0300, Sakari Ailus wrote:
> > On Thu, Jun 29, 2017 at 11:02:03AM +0200, Niklas Söderlund wrote:
> > > Hi Sakari,
> > > 
> > > Thanks for your patch.
> > > 
> > > On 2017-06-29 10:30:10 +0300, 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 | 91 ++++++++++-----------------------
> > > >  drivers/media/platform/omap3isp/isp.h |  3 --
> > > >  drivers/media/v4l2-core/v4l2-fwnode.c | 94 +++++++++++++++++++++++++++++++++++
> > > >  include/media/v4l2-async.h            |  4 +-
> > > >  include/media/v4l2-fwnode.h           |  9 ++++
> > > >  5 files changed, 132 insertions(+), 69 deletions(-)
> > > > 
> > > > diff --git a/drivers/media/platform/omap3isp/isp.c b/drivers/media/platform/omap3isp/isp.c
> > > > index 9df64c1..9ccf883 100644
> > > > --- a/drivers/media/platform/omap3isp/isp.c
> > > > +++ b/drivers/media/platform/omap3isp/isp.c
> > > > @@ -2008,43 +2008,42 @@ 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;
> > > > -
> > > > -	ret = v4l2_fwnode_endpoint_parse(fwnode, &vep);
> > > > -	if (ret)
> > > > -		return ret;
> > > >  
> > > >  	dev_dbg(dev, "parsing endpoint %s, interface %u\n",
> > > > -		to_of_node(fwnode)->full_name, vep.base.port);
> > > > +		to_of_node(vep->base.local_fwnode)->full_name, 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);
> > > > +			!!(vep->bus.parallel.flags & V4L2_MBUS_DATA_ACTIVE_LOW);
> > > >  		break;
> > > >  
> > > >  	case ISP_OF_PHY_CSIPHY1:
> > > >  	case ISP_OF_PHY_CSIPHY2:
> > > >  		/* FIXME: always assume CSI-2 for now. */
> > > > -		switch (vep.base.port) {
> > > > +		switch (vep->base.port) {
> > > >  		case ISP_OF_PHY_CSIPHY1:
> > > >  			buscfg->interface = ISP_INTERFACE_CSI2C_PHY1;
> > > >  			break;
> > > > @@ -2052,18 +2051,19 @@ static int isp_fwnode_parse(struct device *dev, struct fwnode_handle *fwnode,
> > > >  			buscfg->interface = ISP_INTERFACE_CSI2A_PHY2;
> > > >  			break;
> > > >  		}
> > > > -		buscfg->bus.csi2.lanecfg.clk.pos = vep.bus.mipi_csi2.clock_lane;
> > > > +		buscfg->bus.csi2.lanecfg.clk.pos =
> > > > +			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);
> > > >  
> > > >  		for (i = 0; i < ISP_CSIPHY2_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,
> > > >  				buscfg->bus.csi2.lanecfg.data[i].pos);
> > > > @@ -2079,55 +2079,14 @@ static int isp_fwnode_parse(struct device *dev, struct fwnode_handle *fwnode,
> > > >  
> > > >  	default:
> > > >  		dev_warn(dev, "%s: invalid interface %u\n",
> > > > -			 to_of_node(fwnode)->full_name, vep.base.port);
> > > > +			 to_of_node(vep->base.local_fwnode)->full_name,
> > > > +			 vep->base.port);
> > > >  		break;
> > > >  	}
> > > >  
> > > >  	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;
> > > > -
> > > > -		notifier->subdevs[notifier->num_subdevs] = &isd->asd;
> > > > -
> > > > -		if (isp_fwnode_parse(dev, fwnode, isd))
> > > > -			goto error;
> > > > -
> > > > -		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_bound(struct v4l2_async_notifier *async,
> > > >  				     struct v4l2_subdev *subdev,
> > > >  				     struct v4l2_async_subdev *asd)
> > > > @@ -2210,7 +2169,9 @@ static int isp_probe(struct platform_device *pdev)
> > > >  	if (ret)
> > > >  		return ret;
> > > >  
> > > > -	ret = isp_fwnodes_parse(&pdev->dev, &isp->notifier);
> > > > +	ret = v4l2_fwnode_endpoints_parse(
> > > > +		&pdev->dev, &isp->notifier, sizeof(struct isp_async_subdev),
> > > > +		isp_fwnode_parse);
> > > >  	if (ret < 0)
> > > >  		return ret;
> > > >  
> > > > diff --git a/drivers/media/platform/omap3isp/isp.h b/drivers/media/platform/omap3isp/isp.h
> > > > index 2f2ae60..a852c11 100644
> > > > --- a/drivers/media/platform/omap3isp/isp.h
> > > > +++ b/drivers/media/platform/omap3isp/isp.h
> > > > @@ -220,9 +220,6 @@ 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 {
> > > > diff --git a/drivers/media/v4l2-core/v4l2-fwnode.c b/drivers/media/v4l2-core/v4l2-fwnode.c
> > > > index 0ec6c14..b35d525 100644
> > > > --- a/drivers/media/v4l2-core/v4l2-fwnode.c
> > > > +++ b/drivers/media/v4l2-core/v4l2-fwnode.c
> > > > @@ -26,6 +26,7 @@
> > > >  #include <linux/string.h>
> > > >  #include <linux/types.h>
> > > >  
> > > > +#include <media/v4l2-async.h>
> > > >  #include <media/v4l2-fwnode.h>
> > > >  
> > > >  static int v4l2_fwnode_endpoint_parse_csi_bus(struct fwnode_handle *fwnode,
> > > > @@ -339,6 +340,99 @@ void v4l2_fwnode_put_link(struct v4l2_fwnode_link *link)
> > > >  }
> > > >  EXPORT_SYMBOL_GPL(v4l2_fwnode_put_link);
> > > >  
> > > > +static int notifier_realloc(struct device *dev,
> > > > +			    struct v4l2_async_notifier *notifier,
> > > > +			    unsigned int max_subdevs)
> > > > +{
> > > > +	struct v4l2_async_subdev **subdevs;
> > > > +	unsigned int i;
> > > > +
> > > > +	if (max_subdevs <= notifier->max_subdevs)
> > > > +		return 0;
> > > > +
> > > > +	subdevs = devm_kcalloc(
> > > > +		dev, max_subdevs, sizeof(*notifier->subdevs), GFP_KERNEL);
> > > > +	if (!subdevs)
> > > > +		return -ENOMEM;
> > > > +
> > > > +	if (notifier->subdevs) {
> > > > +		for (i = 0; i < notifier->num_subdevs; i++)
> > > > +			subdevs[i] = notifier->subdevs[i];
> > > > +
> > > > +		devm_kfree(dev, notifier->subdevs);
> > > > +	}
> > > > +
> > > > +	notifier->subdevs = subdevs;
> > > > +	notifier->max_subdevs = max_subdevs;
> > > > +
> > > > +	return 0;
> > > > +}
> > > > +
> > > > +int v4l2_fwnode_endpoints_parse(
> > > > +	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))
> > > > +		return -EINVAL;
> > > > +
> > > > +	while ((fwnode = fwnode_graph_get_next_endpoint(dev_fwnode(dev),
> > > > +							fwnode)))
> > > > +		max_subdevs++;
> > > > +
> > > > +	ret = notifier_realloc(dev, notifier, max_subdevs);
> > > > +	if (ret)
> > > > +		return ret;
> > > > +
> > > > +	for (fwnode = NULL; (fwnode = fwnode_graph_get_next_endpoint(
> > > > +				     dev_fwnode(dev), fwnode)) &&
> > > > +		     !WARN_ON(notifier->num_subdevs >= notifier->max_subdevs);
> > > > +		) {
> > > > +		struct v4l2_fwnode_endpoint *vep;
> > > > +		struct v4l2_async_subdev *asd;
> > > > +
> > > > +		asd = devm_kzalloc(dev, asd_struct_size, GFP_KERNEL);
> > > > +		if (!asd) {
> > > > +			ret = -ENOMEM;
> > > > +			goto error;
> > > > +		}
> > > > +
> > > > +		notifier->subdevs[notifier->num_subdevs] = asd;
> > > > +
> > > > +		/* Ignore endpoints the parsing of which failed. */
> > > > +		vep = v4l2_fwnode_endpoint_alloc_parse(fwnode);
> > > > +		if (IS_ERR(vep))
> > > > +			continue;
> > > > +
> > > > +		ret = parse_single(dev, vep, asd);
> > > > +		v4l2_fwnode_endpoint_free(vep);
> > > > +		if (ret)
> > > > +			goto error;
> > > 
> > > First off I think this is a good step in the right direction to create 
> > > core functions for this task.
> > > 
> > > However while reading this I got to think about a use-case I have with 
> > > the Renesas R-Car VIN and CSI-2 drivers where I would not be able to use 
> > > this helper. I have previously posted a patch-set to introduce 
> > > incremental async, see [1]. If that gets picked-up not only the video 
> > > device driver can have use of this helper but subdevices drivers.  As 
> > > the subdevice driver would also need to pars its DT node to search for 
> > > subdevices to add to it's own subnotifier. In this case this helper wont 
> > > suffice, I think.
> > > 
> > > Since the subdevice DT node will contain endpoints pointing to both the 
> > > subdevice which the incremental async notifier would like to find and 
> > > endpoints pointing back to the root video device node it self.
> > > 
> > > In my use-case for Renesas R-Car Gen3 VIN and CSI-2 DT (not yet accepted 
> > > upstream) I have solved this by having the CSI-2 DT node having two port 
> > > nodes, port0 and port1. In port0 endpoints describing the 'upstream' 
> > > video source from the CSI-2 point of view are defined (these should be 
> > > added to the subnotifier). In port1 endpoints describing connections 
> > > back to the VIN video devices are described. Currently the CSI-2 driver 
> > > simply only looks for endpoints in the port0 node to add to its 
> > > subnotifier, and I don't think this would be possible with this helper?
> > 
> > What we could also do is to add a variant of this that parses the endpoints
> > by the port / endpoint IDs. Then you don't need to have a cumbersome way to
> > skip parsing of some ports --- you would have allocated the memory and
> > parsed the port for nothing by the time you call the callback anyway.
> > 
> > That would seem to be a better approach in general. I remember Rob was
> > pushing this for DRM as it greatly simplified driver code there. But then
> > the DT bindings have to be written accordingly: in current bindings the
> > endpoint IDs are mostly undefined.
> > 
> > We may still need to take extra measures to support cases where there are
> > multiple links between two sub-devices.
> > 
> > What do you think?
> 
> A variant of this that as you suggest parses by port I think make sens.  
> I'm not sure how one would go about creating a simple interface which 
> would support parsing by port+endpoint IDs, but if it's possible that 
> would be also be nice.

If you know the IDs in the driver, this will get easier.

> 
> Another option is to instead of passing a struct device pass a struct 
> fwnode_handle which would act as the root search path. That way one 
> could pass a fwnode_handle to a specific port node and just iterate over 
> all endpoints in that port. But that way the driver side implementation 
> becomes more complex since it needs to lookup the fwnode_handle so I'm 
> not sure I think that is the best solution.

You could as well specify the port number using an integer.

The current interface (fwnode_graph_get_remote_node()) also necessitates
having an endpoint number; I don't think that's really an issue. You can
specify the valid endpoint numbers in DT bindings and use them in the
driver.

I'll add that as a new function for the existing implementations are easier
cleaned up by using this one, as well as add documentation.

> 
> So yes I think your suggestion of adding a variant which takes port 
> and/or port+endpoint IDs into account to be the best solution.
> 
> > 
> > Cc Rob + devicetree list as well.
> > 
> > > 
> > > Perhaps this patch can be modified so that en error code from the 
> > > callback parse_single() could be taken in to account when making the 
> > > decision if the parsed endpoint should be added to the notifiers 
> > > list of subdevices?
> > > 
> > > > +
> > > > +		asd->match.fwnode.fwnode =
> > > > +			fwnode_graph_get_remote_port_parent(fwnode);
> > > > +		if (!asd->match.fwnode.fwnode) {
> > > > +			dev_warn(dev, "bad remote port parent\n");
> > > > +			ret = -EINVAL;
> > > > +			goto error;
> > > > +		}
> > > > +
> > > > +		asd->match_type = V4L2_ASYNC_MATCH_FWNODE;
> > > > +		notifier->num_subdevs++;
> > > > +	}
> > > > +
> > > > +error:
> > > > +	fwnode_handle_put(fwnode);
> > > > +	return ret;
> > > > +}
> > > > +EXPORT_SYMBOL_GPL(v4l2_fwnode_endpoints_parse);
> > > > +
> > > >  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 c69d8c8..067f368 100644
> > > > --- a/include/media/v4l2-async.h
> > > > +++ b/include/media/v4l2-async.h
> > > > @@ -78,7 +78,8 @@ 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 +91,7 @@ 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;
> > > > diff --git a/include/media/v4l2-fwnode.h b/include/media/v4l2-fwnode.h
> > > > index ecc1233..ff489f7 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;
> > > >  
> > > >  /**
> > > >   * struct v4l2_fwnode_bus_mipi_csi2 - MIPI CSI-2 bus data structure
> > > > @@ -101,4 +103,11 @@ int v4l2_fwnode_parse_link(struct fwnode_handle *fwnode,
> > > >  			   struct v4l2_fwnode_link *link);
> > > >  void v4l2_fwnode_put_link(struct v4l2_fwnode_link *link);
> > > >  
> > > > +int v4l2_fwnode_endpoints_parse(
> > > > +	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 */
> > > > -- 
> > > > 2.1.4
> > > > 
> > > > 
> > > 
> > > -- 
> > > Regards,
> > > Niklas Söderlund
> > 
> > -- 
> > Sakari Ailus
> > e-mail: sakari.ailus-X3B1VOXEql0@public.gmane.org	XMPP: sailus-PCDdDYkjdNMDXYZnReoRVg@public.gmane.org
> 
> -- 
> Regards,
> Niklas Söderlund

-- 
Sakari Ailus
e-mail: sakari.ailus-X3B1VOXEql0@public.gmane.org	XMPP: sailus-PCDdDYkjdNMDXYZnReoRVg@public.gmane.org
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Re: [PATCH 2/2] v4l: fwnode: Support generic parsing of graph endpoints in V4L2

[Sakari Ailus]

On Thu, Jun 29, 2017 at 12:18:44PM +0200, Niklas Söderlund wrote:
> On 2017-06-29 12:57:55 +0300, Sakari Ailus wrote:
> > On Thu, Jun 29, 2017 at 11:02:03AM +0200, Niklas Söderlund wrote:
> > > Hi Sakari,
> > > 
> > > Thanks for your patch.
> > > 
> > > On 2017-06-29 10:30:10 +0300, 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 | 91 ++++++++++-----------------------
> > > >  drivers/media/platform/omap3isp/isp.h |  3 --
> > > >  drivers/media/v4l2-core/v4l2-fwnode.c | 94 +++++++++++++++++++++++++++++++++++
> > > >  include/media/v4l2-async.h            |  4 +-
> > > >  include/media/v4l2-fwnode.h           |  9 ++++
> > > >  5 files changed, 132 insertions(+), 69 deletions(-)
> > > > 
> > > > diff --git a/drivers/media/platform/omap3isp/isp.c b/drivers/media/platform/omap3isp/isp.c
> > > > index 9df64c1..9ccf883 100644
> > > > --- a/drivers/media/platform/omap3isp/isp.c
> > > > +++ b/drivers/media/platform/omap3isp/isp.c
> > > > @@ -2008,43 +2008,42 @@ 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;
> > > > -
> > > > -	ret = v4l2_fwnode_endpoint_parse(fwnode, &vep);
> > > > -	if (ret)
> > > > -		return ret;
> > > >  
> > > >  	dev_dbg(dev, "parsing endpoint %s, interface %u\n",
> > > > -		to_of_node(fwnode)->full_name, vep.base.port);
> > > > +		to_of_node(vep->base.local_fwnode)->full_name, 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);
> > > > +			!!(vep->bus.parallel.flags & V4L2_MBUS_DATA_ACTIVE_LOW);
> > > >  		break;
> > > >  
> > > >  	case ISP_OF_PHY_CSIPHY1:
> > > >  	case ISP_OF_PHY_CSIPHY2:
> > > >  		/* FIXME: always assume CSI-2 for now. */
> > > > -		switch (vep.base.port) {
> > > > +		switch (vep->base.port) {
> > > >  		case ISP_OF_PHY_CSIPHY1:
> > > >  			buscfg->interface = ISP_INTERFACE_CSI2C_PHY1;
> > > >  			break;
> > > > @@ -2052,18 +2051,19 @@ static int isp_fwnode_parse(struct device *dev, struct fwnode_handle *fwnode,
> > > >  			buscfg->interface = ISP_INTERFACE_CSI2A_PHY2;
> > > >  			break;
> > > >  		}
> > > > -		buscfg->bus.csi2.lanecfg.clk.pos = vep.bus.mipi_csi2.clock_lane;
> > > > +		buscfg->bus.csi2.lanecfg.clk.pos =
> > > > +			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);
> > > >  
> > > >  		for (i = 0; i < ISP_CSIPHY2_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,
> > > >  				buscfg->bus.csi2.lanecfg.data[i].pos);
> > > > @@ -2079,55 +2079,14 @@ static int isp_fwnode_parse(struct device *dev, struct fwnode_handle *fwnode,
> > > >  
> > > >  	default:
> > > >  		dev_warn(dev, "%s: invalid interface %u\n",
> > > > -			 to_of_node(fwnode)->full_name, vep.base.port);
> > > > +			 to_of_node(vep->base.local_fwnode)->full_name,
> > > > +			 vep->base.port);
> > > >  		break;
> > > >  	}
> > > >  
> > > >  	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;
> > > > -
> > > > -		notifier->subdevs[notifier->num_subdevs] = &isd->asd;
> > > > -
> > > > -		if (isp_fwnode_parse(dev, fwnode, isd))
> > > > -			goto error;
> > > > -
> > > > -		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_bound(struct v4l2_async_notifier *async,
> > > >  				     struct v4l2_subdev *subdev,
> > > >  				     struct v4l2_async_subdev *asd)
> > > > @@ -2210,7 +2169,9 @@ static int isp_probe(struct platform_device *pdev)
> > > >  	if (ret)
> > > >  		return ret;
> > > >  
> > > > -	ret = isp_fwnodes_parse(&pdev->dev, &isp->notifier);
> > > > +	ret = v4l2_fwnode_endpoints_parse(
> > > > +		&pdev->dev, &isp->notifier, sizeof(struct isp_async_subdev),
> > > > +		isp_fwnode_parse);
> > > >  	if (ret < 0)
> > > >  		return ret;
> > > >  
> > > > diff --git a/drivers/media/platform/omap3isp/isp.h b/drivers/media/platform/omap3isp/isp.h
> > > > index 2f2ae60..a852c11 100644
> > > > --- a/drivers/media/platform/omap3isp/isp.h
> > > > +++ b/drivers/media/platform/omap3isp/isp.h
> > > > @@ -220,9 +220,6 @@ 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 {
> > > > diff --git a/drivers/media/v4l2-core/v4l2-fwnode.c b/drivers/media/v4l2-core/v4l2-fwnode.c
> > > > index 0ec6c14..b35d525 100644
> > > > --- a/drivers/media/v4l2-core/v4l2-fwnode.c
> > > > +++ b/drivers/media/v4l2-core/v4l2-fwnode.c
> > > > @@ -26,6 +26,7 @@
> > > >  #include <linux/string.h>
> > > >  #include <linux/types.h>
> > > >  
> > > > +#include <media/v4l2-async.h>
> > > >  #include <media/v4l2-fwnode.h>
> > > >  
> > > >  static int v4l2_fwnode_endpoint_parse_csi_bus(struct fwnode_handle *fwnode,
> > > > @@ -339,6 +340,99 @@ void v4l2_fwnode_put_link(struct v4l2_fwnode_link *link)
> > > >  }
> > > >  EXPORT_SYMBOL_GPL(v4l2_fwnode_put_link);
> > > >  
> > > > +static int notifier_realloc(struct device *dev,
> > > > +			    struct v4l2_async_notifier *notifier,
> > > > +			    unsigned int max_subdevs)
> > > > +{
> > > > +	struct v4l2_async_subdev **subdevs;
> > > > +	unsigned int i;
> > > > +
> > > > +	if (max_subdevs <= notifier->max_subdevs)
> > > > +		return 0;
> > > > +
> > > > +	subdevs = devm_kcalloc(
> > > > +		dev, max_subdevs, sizeof(*notifier->subdevs), GFP_KERNEL);
> > > > +	if (!subdevs)
> > > > +		return -ENOMEM;
> > > > +
> > > > +	if (notifier->subdevs) {
> > > > +		for (i = 0; i < notifier->num_subdevs; i++)
> > > > +			subdevs[i] = notifier->subdevs[i];
> > > > +
> > > > +		devm_kfree(dev, notifier->subdevs);
> > > > +	}
> > > > +
> > > > +	notifier->subdevs = subdevs;
> > > > +	notifier->max_subdevs = max_subdevs;
> > > > +
> > > > +	return 0;
> > > > +}
> > > > +
> > > > +int v4l2_fwnode_endpoints_parse(
> > > > +	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))
> > > > +		return -EINVAL;
> > > > +
> > > > +	while ((fwnode = fwnode_graph_get_next_endpoint(dev_fwnode(dev),
> > > > +							fwnode)))
> > > > +		max_subdevs++;
> > > > +
> > > > +	ret = notifier_realloc(dev, notifier, max_subdevs);
> > > > +	if (ret)
> > > > +		return ret;
> > > > +
> > > > +	for (fwnode = NULL; (fwnode = fwnode_graph_get_next_endpoint(
> > > > +				     dev_fwnode(dev), fwnode)) &&
> > > > +		     !WARN_ON(notifier->num_subdevs >= notifier->max_subdevs);
> > > > +		) {
> > > > +		struct v4l2_fwnode_endpoint *vep;
> > > > +		struct v4l2_async_subdev *asd;
> > > > +
> > > > +		asd = devm_kzalloc(dev, asd_struct_size, GFP_KERNEL);
> > > > +		if (!asd) {
> > > > +			ret = -ENOMEM;
> > > > +			goto error;
> > > > +		}
> > > > +
> > > > +		notifier->subdevs[notifier->num_subdevs] = asd;
> > > > +
> > > > +		/* Ignore endpoints the parsing of which failed. */
> > > > +		vep = v4l2_fwnode_endpoint_alloc_parse(fwnode);
> > > > +		if (IS_ERR(vep))
> > > > +			continue;
> > > > +
> > > > +		ret = parse_single(dev, vep, asd);
> > > > +		v4l2_fwnode_endpoint_free(vep);
> > > > +		if (ret)
> > > > +			goto error;
> > > 
> > > First off I think this is a good step in the right direction to create 
> > > core functions for this task.
> > > 
> > > However while reading this I got to think about a use-case I have with 
> > > the Renesas R-Car VIN and CSI-2 drivers where I would not be able to use 
> > > this helper. I have previously posted a patch-set to introduce 
> > > incremental async, see [1]. If that gets picked-up not only the video 
> > > device driver can have use of this helper but subdevices drivers.  As 
> > > the subdevice driver would also need to pars its DT node to search for 
> > > subdevices to add to it's own subnotifier. In this case this helper wont 
> > > suffice, I think.
> > > 
> > > Since the subdevice DT node will contain endpoints pointing to both the 
> > > subdevice which the incremental async notifier would like to find and 
> > > endpoints pointing back to the root video device node it self.
> > > 
> > > In my use-case for Renesas R-Car Gen3 VIN and CSI-2 DT (not yet accepted 
> > > upstream) I have solved this by having the CSI-2 DT node having two port 
> > > nodes, port0 and port1. In port0 endpoints describing the 'upstream' 
> > > video source from the CSI-2 point of view are defined (these should be 
> > > added to the subnotifier). In port1 endpoints describing connections 
> > > back to the VIN video devices are described. Currently the CSI-2 driver 
> > > simply only looks for endpoints in the port0 node to add to its 
> > > subnotifier, and I don't think this would be possible with this helper?
> > 
> > What we could also do is to add a variant of this that parses the endpoints
> > by the port / endpoint IDs. Then you don't need to have a cumbersome way to
> > skip parsing of some ports --- you would have allocated the memory and
> > parsed the port for nothing by the time you call the callback anyway.
> > 
> > That would seem to be a better approach in general. I remember Rob was
> > pushing this for DRM as it greatly simplified driver code there. But then
> > the DT bindings have to be written accordingly: in current bindings the
> > endpoint IDs are mostly undefined.
> > 
> > We may still need to take extra measures to support cases where there are
> > multiple links between two sub-devices.
> > 
> > What do you think?
> 
> A variant of this that as you suggest parses by port I think make sens.  
> I'm not sure how one would go about creating a simple interface which 
> would support parsing by port+endpoint IDs, but if it's possible that 
> would be also be nice.

If you know the IDs in the driver, this will get easier.

> 
> Another option is to instead of passing a struct device pass a struct 
> fwnode_handle which would act as the root search path. That way one 
> could pass a fwnode_handle to a specific port node and just iterate over 
> all endpoints in that port. But that way the driver side implementation 
> becomes more complex since it needs to lookup the fwnode_handle so I'm 
> not sure I think that is the best solution.

You could as well specify the port number using an integer.

The current interface (fwnode_graph_get_remote_node()) also necessitates
having an endpoint number; I don't think that's really an issue. You can
specify the valid endpoint numbers in DT bindings and use them in the
driver.

I'll add that as a new function for the existing implementations are easier
cleaned up by using this one, as well as add documentation.

> 
> So yes I think your suggestion of adding a variant which takes port 
> and/or port+endpoint IDs into account to be the best solution.
> 
> > 
> > Cc Rob + devicetree list as well.
> > 
> > > 
> > > Perhaps this patch can be modified so that en error code from the 
> > > callback parse_single() could be taken in to account when making the 
> > > decision if the parsed endpoint should be added to the notifiers 
> > > list of subdevices?
> > > 
> > > > +
> > > > +		asd->match.fwnode.fwnode =
> > > > +			fwnode_graph_get_remote_port_parent(fwnode);
> > > > +		if (!asd->match.fwnode.fwnode) {
> > > > +			dev_warn(dev, "bad remote port parent\n");
> > > > +			ret = -EINVAL;
> > > > +			goto error;
> > > > +		}
> > > > +
> > > > +		asd->match_type = V4L2_ASYNC_MATCH_FWNODE;
> > > > +		notifier->num_subdevs++;
> > > > +	}
> > > > +
> > > > +error:
> > > > +	fwnode_handle_put(fwnode);
> > > > +	return ret;
> > > > +}
> > > > +EXPORT_SYMBOL_GPL(v4l2_fwnode_endpoints_parse);
> > > > +
> > > >  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 c69d8c8..067f368 100644
> > > > --- a/include/media/v4l2-async.h
> > > > +++ b/include/media/v4l2-async.h
> > > > @@ -78,7 +78,8 @@ 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 +91,7 @@ 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;
> > > > diff --git a/include/media/v4l2-fwnode.h b/include/media/v4l2-fwnode.h
> > > > index ecc1233..ff489f7 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;
> > > >  
> > > >  /**
> > > >   * struct v4l2_fwnode_bus_mipi_csi2 - MIPI CSI-2 bus data structure
> > > > @@ -101,4 +103,11 @@ int v4l2_fwnode_parse_link(struct fwnode_handle *fwnode,
> > > >  			   struct v4l2_fwnode_link *link);
> > > >  void v4l2_fwnode_put_link(struct v4l2_fwnode_link *link);
> > > >  
> > > > +int v4l2_fwnode_endpoints_parse(
> > > > +	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 */
> > > > -- 
> > > > 2.1.4
> > > > 
> > > > 
> > > 
> > > -- 
> > > Regards,
> > > Niklas Söderlund
> > 
> > -- 
> > Sakari Ailus
> > e-mail: sakari.ailus@iki.fi	XMPP: sailus@retiisi.org.uk
> 
> -- 
> Regards,
> Niklas Söderlund

-- 
Sakari Ailus
e-mail: sakari.ailus@iki.fi	XMPP: sailus@retiisi.org.uk