Re: [PATCH/RFC v3 06/19] video: display: OF support

Hi Philipp,

On Wednesday 04 September 2013 16:21:38 Philipp Zabel wrote:

Am Samstag, den 10.08.2013, 01:03 +0200 schrieb Laurent Pinchart:

...

Extend the notifier with DT node matching support, and add helper functions to build the notifier and link entities based on a graph representation in DT.

Signed-off-by: Laurent Pinchart

laurent.pinchart+renesas@ideasonboard.com

drivers/video/display/display-core.c | 334 ++++++++++++++++++++++++++ drivers/video/display/display-notifier.c | 187 +++++++++++++++++ include/video/display.h | 45 +++++ 3 files changed, 566 insertions(+)

diff --git a/drivers/video/display/display-core.c b/drivers/video/display/display-core.c index c3b47d3..328ead7 100644 --- a/drivers/video/display/display-core.c +++ b/drivers/video/display/display-core.c

[...]

...

@@ -420,6 +599,161 @@ int display_entity_link_graph(struct device *dev, struct list_head *entities)> } EXPORT_SYMBOL_GPL(display_entity_link_graph);

+#ifdef CONFIG_OF

+static int display_of_entity_link_entity(struct device *dev,

• 			 struct display_entity *entity,
  

• 			 struct list_head *entities,
  

• 			 struct display_entity *root)
  

+{

• u32 link_flags = MEDIA_LNK_FL_IMMUTABLE | MEDIA_LNK_FL_ENABLED;
• const struct device_node *node = entity->dev->of_node;

the current device tree matching implementation only allows one display entity per linux device. How about adding an of_node pointer to struct display_entity directly and allow multiple display entity nodes below in a single device node in the device tree?

That's a very good point. We had a similar issues in V4L2, with sensors that would create several entities. However, in those cases, the sensors would be connected to the rest of the pipeline through a single entity :

Sensor Entity 1 -> ... -> Sensor Entity N -> V4L2 pipeline ...

The core code thus had to care about a single sensor entity when building the pipeline. We could solve the problem in a similar way for panels, but encoders need a more elaborate solution.

I see (at least) two possibilities here, either explicitly describing all entities that make the device in DT (as you have proposed below), or creating a hierarchy of entities, with parent entities that can contain several child entities. I've CC'ed Guennadi, Hans, Sylwester and Sakari to get their opinion on the matter.

lvds-encoder { channel@0 {

If I understand this correctly, your LVDS encoder has two independent channels. In the general case a device made of multiple entities might have those entities chained, so "channel" might not be the best term. "entity" might be a better choice.

port@0 {
	lvds0_input: endpoint {
	};
};
port@1 {
	lvds0_output: endpoint {
	};
};

}; channel@1 { port@0 { lvds1_input: endpoint { }; }; lvds1: port@1 { lvds1_output: endpoint { }; }; }; };

...

• struct media_entity *local = &entity->entity;
• struct device_node *ep = NULL;
• int ret = 0;
• dev_dbg(dev, "creating links for entity %s\n", local->name);
• while (1) {

• struct media_entity *remote = NULL;
  

• struct media_pad *remote_pad;
  

• struct media_pad *local_pad;
  

• struct display_of_link link;
  

• struct display_entity *ent;
  

• struct device_node *next;
  

• /* Get the next endpoint and parse its link. */
  

• next = display_of_get_next_endpoint(node, ep);
  

• if (next == NULL)
  

• 	break;
  

• of_node_put(ep);
  

• ep = next;
  

• dev_dbg(dev, "processing endpoint %s\n", ep->full_name);
  

• ret = display_of_parse_link(ep, &link);
  

• if (ret < 0) {
  

• 	dev_err(dev, "failed to parse link for %s\n",
  

• 		ep->full_name);
  

• 	continue;
  

• }
  

• /* Skip source pads, they will be processed from the other end of
  

•  * the link.
  

•  */
  

• if (link.local_port >= local->num_pads) {
  

• 	dev_err(dev, "invalid port number %u on %s\n",
  

• 		link.local_port, link.local_node->full_name);
  

• 	display_of_put_link(&link);
  

• 	ret = -EINVAL;
  

• 	break;
  

• }
  

• local_pad = &local->pads[link.local_port];
  

• if (local_pad->flags & MEDIA_PAD_FL_SOURCE) {
  

• 	dev_dbg(dev, "skipping source port %s:%u\n",
  

• 		link.local_node->full_name, link.local_port);
  

• 	display_of_put_link(&link);
  

• 	continue;
  

• }
  

• /* Find the remote entity. If not found, just skip the link as
  

•  * it goes out of scope of the entities handled by the notifier.
  

•  */
  

• list_for_each_entry(ent, entities, list) {
  

• 	if (ent->dev->of_node == link.remote_node) {
  

• 		remote = &ent->entity;
  

• 		break;
  

• 	}
  

• }
  

• if (root->dev->of_node == link.remote_node)
  

• 	remote = &root->entity;
  

• if (remote == NULL) {
  

• 	dev_dbg(dev, "no entity found for %s\n",
  

• 		link.remote_node->full_name);
  

• 	display_of_put_link(&link);
  

• 	continue;
  

• }
  

• if (link.remote_port >= remote->num_pads) {
  

• 	dev_err(dev, "invalid port number %u on %s\n",
  

• 		link.remote_port, link.remote_node->full_name);
  

• 	display_of_put_link(&link);
  

• 	ret = -EINVAL;
  

• 	break;
  

• }
  

• remote_pad = &remote->pads[link.remote_port];
  

• display_of_put_link(&link);
  

• /* Create the media link. */
  

• dev_dbg(dev, "creating %s:%u -> %s:%u link\n",
  

• 	remote->name, remote_pad->index,
  

• 	local->name, local_pad->index);
  

• ret = media_entity_create_link(remote, remote_pad->index,
  

• 			       local, local_pad->index,
  

• 			       link_flags);
  

• if (ret < 0) {
  

• 	dev_err(dev,
  

• 		"failed to create %s:%u -> %s:%u link\n",
  

• 		remote->name, remote_pad->index,
  

• 		local->name, local_pad->index);
  

• 	break;
  

• }
  

• }
• of_node_put(ep);
• return ret;

+}

[...]

For example like this:

diff --git a/drivers/video/display/display-core.c b/drivers/video/display/display-core.c index 7910c23..a04feed 100644 --- a/drivers/video/display/display-core.c +++ b/drivers/video/display/display-core.c @@ -302,6 +302,9 @@ int display_entity_init(struct display_entity *entity, unsigned int num_sinks, kref_init(&entity->ref); entity->state = DISPLAY_ENTITY_STATE_OFF;

• if (!entity->of_node && entity->dev)

• entity->of_node = entity->dev->of_node;
  

• num_pads = num_sinks + num_sources; pads = kzalloc(sizeof(*pads) * num_pads, GFP_KERNEL); if (pads == NULL)

@@ -665,7 +668,7 @@ static int display_of_entity_link_entity(struct device *dev, struct display_entity *root) { u32 link_flags = MEDIA_LNK_FL_IMMUTABLE | MEDIA_LNK_FL_ENABLED;

• const struct device_node *node = entity->dev->of_node;

• const struct device_node *node = entity->of_node; struct media_entity *local = &entity->entity; struct device_node *ep = NULL; int num_sink, ret = 0;

@@ -727,13 +730,13 @@ static int display_of_entity_link_entity(struct device *dev, * it goes out of scope of the entities handled by the notifier. */ list_for_each_entry(ent, entities, list) {

• 	if (ent->dev->of_node == link.remote_node) {
  

• 	if (ent->of_node == link.remote_node) {
  	remote = &ent->entity;
  	break;
  }
  

  }

• if (root && root->dev->of_node == link.remote_node)
  

• if (root && root->of_node == link.remote_node)
  remote = &root->entity;
  
  

  if (remote == NULL) {

diff --git a/drivers/video/display/display-notifier.c b/drivers/video/display/display-notifier.c index a3998c7..d0da6e5 100644 --- a/drivers/video/display/display-notifier.c +++ b/drivers/video/display/display-notifier.c @@ -28,28 +28,30 @@ static DEFINE_MUTEX(display_entity_mutex);

• Notifiers

*/

-static bool match_platform(struct device *dev, +static bool match_platform(struct display_entity *entity, struct display_entity_match *match) { pr_debug("%s: matching device '%s' with name '%s'\n", __func__,

•  dev_name(dev), match->match.platform.name);
  

•  dev_name(entity->dev), match->match.platform.name);
  
  

• return !strcmp(match->match.platform.name, dev_name(dev));

• return !strcmp(match->match.platform.name, dev_name(entity->dev));

}

-static bool match_dt(struct device *dev, struct display_entity_match *match) +static bool match_dt(struct display_entity *entity,

•      struct display_entity_match *match)
  

{ pr_debug("%s: matching device node '%s' with node '%s'\n", __func__,

•  dev->of_node->full_name, match->match.dt.node->full_name);
  

•  entity->of_node->full_name, match->match.dt.node->full_name);
  
  

• return match->match.dt.node == dev->of_node;

• return match->match.dt.node == entity->of_node;

}

static struct display_entity_match * display_entity_notifier_match(struct display_entity_notifier *notifier, struct display_entity *entity) {

• bool (*match_func)(struct device *, struct display_entity_match *);

• bool (*match_func)(struct display_entity *,

• 	   struct display_entity_match *);
  

  struct display_entity_match *match;

  pr_debug("%s: matching entity '%s' (ptr 0x%p dev '%s')\n", __func__,

@@ -66,7 +68,7 @@ display_entity_notifier_match(struct display_entity_notifier *notifier, break; }

• if (match_func(entity->dev, match))
  

• if (match_func(entity, match))
  return match;
  

  }

diff --git a/include/video/display.h b/include/video/display.h index 4c402bee..d1f8833 100644 --- a/include/video/display.h +++ b/include/video/display.h @@ -228,6 +228,7 @@ struct display_entity { struct list_head list; struct device *dev; struct module *owner;

• struct device_node *of_node; struct kref ref;

  char name[32];