[RFC] drivers: base: component: these can be part of more than one aggregate

[Ben Dooks]

Sending as an RFC as there is still a couple of todo comments and
I am not completely sure this is bug-free yet.

When dealing with newer qualcomm devices they can have a gpu associated
with more than one display controller. With each displayer controller
being an aggregate device only one will start with the others being
held as they will never find the gpu and thus never get bound.

To try and sort this out, make each component have a list of all
the aggregate devices it is part of. To avoid adding more structs
we add a list node to each of the match which can have a component
and use that to avoid adding a lot more code.

Signed-off-by: Ben Dooks <ben.dooks@xxxxxxxxxxxxxxx>
---
 drivers/base/component.c | 93 +++++++++++++++++++++++++++++-----------
 1 file changed, 68 insertions(+), 25 deletions(-)

diff --git a/drivers/base/component.c b/drivers/base/component.c
index 5d1eb5d82462a..f9e1a6ecf3143 100644
--- a/drivers/base/component.c
+++ b/drivers/base/component.c
@@ -37,6 +37,7 @@
  */
 
 struct component;
+struct aggregate_device;
 
 struct component_match_array {
 	void *data;
@@ -44,6 +45,8 @@ struct component_match_array {
 	int (*compare_typed)(struct device *, int, void *);
 	void (*release)(struct device *, void *);
 	struct component *component;
+	struct list_head component_list;
+	struct aggregate_device *adev;
 	bool duplicate;
 };
 
@@ -64,7 +67,7 @@ struct aggregate_device {
 
 struct component {
 	struct list_head node;
-	struct aggregate_device *adev;
+	struct list_head agdevs;
 	bool bound;
 
 	const struct component_ops *ops;
@@ -156,9 +159,6 @@ static struct component *find_component(struct aggregate_device *adev,
 	struct component *c;
 
 	list_for_each_entry(c, &component_list, node) {
-		if (c->adev && c->adev != adev)
-			continue;
-
 		if (mc->compare && mc->compare(c->dev, mc->data))
 			return c;
 
@@ -170,6 +170,38 @@ static struct component *find_component(struct aggregate_device *adev,
 	return NULL;
 }
 
+static bool component_match_adev(struct component *c,
+				 struct aggregate_device *adev)
+{
+	struct component_match *match = adev->match;
+	size_t i;
+
+	for (i = 0; i < match->num; i++) {
+		struct component_match_array *mc = &match->compare[i];
+
+		if (mc->component == c)
+			return true;
+	}
+
+	return false;
+}
+
+static void component_remove_adev(struct component *c,
+				   struct aggregate_device *adev)
+{
+	struct component_match *match = adev->match;
+	size_t i;
+
+	for (i = 0; i < match->num; i++) {
+		struct component_match_array *mc = &match->compare[i];
+
+		if (mc->component == c) {
+			list_del(&mc->component_list);
+			mc->component = NULL;
+		}
+	}
+}
+
 static int find_components(struct aggregate_device *adev)
 {
 	struct component_match *match = adev->match;
@@ -183,6 +215,7 @@ static int find_components(struct aggregate_device *adev)
 	for (i = 0; i < match->num; i++) {
 		struct component_match_array *mc = &match->compare[i];
 		struct component *c;
+		bool duplicate;
 
 		dev_dbg(adev->parent, "Looking for component %zu\n", i);
 
@@ -195,28 +228,19 @@ static int find_components(struct aggregate_device *adev)
 			break;
 		}
 
+		duplicate = component_match_adev(c, adev);
 		dev_dbg(adev->parent, "found component %s, duplicate %u\n",
-			dev_name(c->dev), !!c->adev);
+			dev_name(c->dev), duplicate);
 
 		/* Attach this component to the adev */
-		match->compare[i].duplicate = !!c->adev;
+		match->compare[i].duplicate = duplicate;
 		match->compare[i].component = c;
-		c->adev = adev;
+		match->compare[i].adev = adev;
+		list_add(&match->compare[i].component_list, &c->agdevs);
 	}
 	return ret;
 }
 
-/* Detach component from associated aggregate_device */
-static void remove_component(struct aggregate_device *adev, struct component *c)
-{
-	size_t i;
-
-	/* Detach the component from this adev. */
-	for (i = 0; i < adev->match->num; i++)
-		if (adev->match->compare[i].component == c)
-			adev->match->compare[i].component = NULL;
-}
-
 /*
  * Try to bring up an aggregate device.  If component is NULL, we're interested
  * in this aggregate device, otherwise it's a component which must be present
@@ -236,7 +260,7 @@ static int try_to_bring_up_aggregate_device(struct aggregate_device *adev,
 		return 0;
 	}
 
-	if (component && component->adev != adev) {
+	if (component && !component_match_adev(component, adev)) {
 		dev_dbg(adev->parent, "master is not for this component (%s)\n",
 			dev_name(component->dev));
 		return 0;
@@ -494,7 +518,7 @@ static void free_aggregate_device(struct aggregate_device *adev)
 		for (i = 0; i < match->num; i++) {
 			struct component *c = match->compare[i].component;
 			if (c)
-				c->adev = NULL;
+				component_remove_adev(c, adev);
 		}
 	}
 
@@ -749,8 +773,21 @@ static int __component_add(struct device *dev, const struct component_ops *ops,
 
 	ret = try_to_bring_up_masters(component);
 	if (ret < 0) {
-		if (component->adev)
-			remove_component(component->adev, component);
+		// if we don't bind, do we have to remove all masters from component?
+		// todo: also do we need to remove in reverse order?
+		struct list_head *ptr, *tmp;
+		struct component_match_array *mc;
+
+		list_for_each_safe(ptr, tmp, &component->agdevs) {
+			mc = list_entry(ptr, struct component_match_array, component_list);
+
+			list_del(&mc->component_list);
+			mc->component = NULL;
+
+			if (!mc->duplicate)
+				take_down_aggregate_device(mc->adev);
+		}
+
 		list_del(&component->node);
 
 		kfree(component);
@@ -822,6 +859,8 @@ EXPORT_SYMBOL_GPL(component_add);
 void component_del(struct device *dev, const struct component_ops *ops)
 {
 	struct component *c, *component = NULL;
+	struct list_head *ptr, *tmp;
+	struct component_match_array *mc;
 
 	mutex_lock(&component_mutex);
 	list_for_each_entry(c, &component_list, node)
@@ -831,9 +870,13 @@ void component_del(struct device *dev, const struct component_ops *ops)
 			break;
 		}
 
-	if (component && component->adev) {
-		take_down_aggregate_device(component->adev);
-		remove_component(component->adev, component);
+	list_for_each_safe(ptr, tmp, &component->agdevs) {
+		mc = list_entry(ptr, struct component_match_array, component_list);
+		list_del(&mc->component_list);
+		mc->component = NULL;
+
+		if (!mc->duplicate)
+			take_down_aggregate_device(mc->adev);
 	}
 
 	mutex_unlock(&component_mutex);
-- 
2.37.2.352.g3c44437643