[RFC 1/2] drm/connector: add connector list iteration with filtering

[Jani Nikula <jani.nikula@xxxxxxxxx>]

Add new function drm_connector_list_iter_filter_begin() to initialize
connector list iterator with a filter function. Subsequent iteration on
the list will only return connectors on which the filter function
returns true.

Cc: Arun R Murthy <arun.r.murthy@xxxxxxxxx>
Cc: Suraj Kandpal <suraj.kandpal@xxxxxxxxx>
Cc: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
Signed-off-by: Jani Nikula <jani.nikula@xxxxxxxxx>
---
 drivers/gpu/drm/drm_connector.c | 57 ++++++++++++++++++++++++++-------
 include/drm/drm_connector.h     |  9 ++++++
 2 files changed, 54 insertions(+), 12 deletions(-)

diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c
index e3142c8142b3..d54b4b54cecb 100644
--- a/drivers/gpu/drm/drm_connector.c
+++ b/drivers/gpu/drm/drm_connector.c
@@ -762,6 +762,29 @@ static struct lockdep_map connector_list_iter_dep_map = {
 };
 #endif
 
+/**
+ * drm_connector_list_iter_filter_begin - initialize a connector_list iterator with filter
+ * @dev: DRM device
+ * @iter: connector_list iterator
+ * @filter: connector filter function
+ * @filter_context: context to be passed to the filter function
+ *
+ * Same as drm_connector_list_iter_begin(), but sets up the iterator to only
+ * return connectors where filter(connector) returns true.
+ */
+void drm_connector_list_iter_filter_begin(struct drm_device *dev,
+					  struct drm_connector_list_iter *iter,
+					  drm_connector_list_iter_filter_fn filter,
+					  void *filter_context)
+{
+	iter->dev = dev;
+	iter->conn = NULL;
+	iter->filter = filter;
+	iter->filter_context = filter_context;
+	lock_acquire_shared_recursive(&connector_list_iter_dep_map, 0, 1, NULL, _RET_IP_);
+}
+EXPORT_SYMBOL(drm_connector_list_iter_filter_begin);
+
 /**
  * drm_connector_list_iter_begin - initialize a connector_list iterator
  * @dev: DRM device
@@ -775,9 +798,7 @@ static struct lockdep_map connector_list_iter_dep_map = {
 void drm_connector_list_iter_begin(struct drm_device *dev,
 				   struct drm_connector_list_iter *iter)
 {
-	iter->dev = dev;
-	iter->conn = NULL;
-	lock_acquire_shared_recursive(&connector_list_iter_dep_map, 0, 1, NULL, _RET_IP_);
+	drm_connector_list_iter_filter_begin(dev, iter, NULL, NULL);
 }
 EXPORT_SYMBOL(drm_connector_list_iter_begin);
 
@@ -800,15 +821,8 @@ __drm_connector_put_safe(struct drm_connector *conn)
 	schedule_work(&config->connector_free_work);
 }
 
-/**
- * drm_connector_list_iter_next - return next connector
- * @iter: connector_list iterator
- *
- * Returns: the next connector for @iter, or NULL when the list walk has
- * completed.
- */
-struct drm_connector *
-drm_connector_list_iter_next(struct drm_connector_list_iter *iter)
+static struct drm_connector *
+__drm_connector_list_iter_next(struct drm_connector_list_iter *iter)
 {
 	struct drm_connector *old_conn = iter->conn;
 	struct drm_mode_config *config = &iter->dev->mode_config;
@@ -836,6 +850,25 @@ drm_connector_list_iter_next(struct drm_connector_list_iter *iter)
 
 	return iter->conn;
 }
+
+/**
+ * drm_connector_list_iter_next - return next connector
+ * @iter: connector_list iterator
+ *
+ * Returns: the next connector for @iter, or NULL when the list walk has
+ * completed.
+ */
+struct drm_connector *
+drm_connector_list_iter_next(struct drm_connector_list_iter *iter)
+{
+	struct drm_connector *connector;
+
+	while ((connector = __drm_connector_list_iter_next(iter)) &&
+	       iter->filter && !iter->filter(connector, iter->filter_context))
+		;
+
+	return connector;
+}
 EXPORT_SYMBOL(drm_connector_list_iter_next);
 
 /**
diff --git a/include/drm/drm_connector.h b/include/drm/drm_connector.h
index 56aee949c6fa..497b98197d3a 100644
--- a/include/drm/drm_connector.h
+++ b/include/drm/drm_connector.h
@@ -1868,6 +1868,9 @@ struct drm_tile_group *drm_mode_get_tile_group(struct drm_device *dev,
 void drm_mode_put_tile_group(struct drm_device *dev,
 			     struct drm_tile_group *tg);
 
+typedef bool (*drm_connector_list_iter_filter_fn)(const struct drm_connector *connector,
+						  void *filter_context);
+
 /**
  * struct drm_connector_list_iter - connector_list iterator
  *
@@ -1886,10 +1889,16 @@ struct drm_connector_list_iter {
 /* private: */
 	struct drm_device *dev;
 	struct drm_connector *conn;
+	drm_connector_list_iter_filter_fn filter;
+	void *filter_context;
 };
 
 void drm_connector_list_iter_begin(struct drm_device *dev,
 				   struct drm_connector_list_iter *iter);
+void drm_connector_list_iter_filter_begin(struct drm_device *dev,
+					  struct drm_connector_list_iter *iter,
+					  drm_connector_list_iter_filter_fn filter,
+					  void *filter_context);
 struct drm_connector *
 drm_connector_list_iter_next(struct drm_connector_list_iter *iter);
 void drm_connector_list_iter_end(struct drm_connector_list_iter *iter);
-- 
2.34.1