drm/bridge: make bridge registration independent of drm flow

Currently, third party bridge drivers(ptn3460) are dependent
on the corresponding encoder driver init, since bridge driver
needs a drm_device pointer to finish drm initializations.
The encoder driver passes the drm_device pointer to the
bridge driver. Because of this dependency, third party drivers
like ptn3460 doesn't adhere to the driver model.

In this patch, we reframe the bridge registration framework
so that bridge initialization is split into 2 steps, and
bridge registration happens independent of drm flow:
--Step 1: gather all the bridge settings independent of drm and
	  add the bridge onto a global list of bridges.
--Step 2: when the encoder driver is probed, call drm_bridge_attach
	  for the corresponding bridge so that the bridge receives
	  drm_device pointer and continues with connector and other
	  drm initializations.

The old set of bridge helpers are removed, and a set of new helpers
are added to accomplish the 2 step initialization.

The bridge devices register themselves onto global list of bridges
when they get probed by calling "drm_bridge_add".

The parent encoder driver waits till the bridge is available
in the lookup table(by calling "of_drm_find_bridge") and then
continues with its initialization.

The encoder driver should also call "drm_bridge_attach" to pass
on the drm_device to the bridge object.

drm_bridge_attach inturn calls "bridge->funcs->attach" so that
bridge can continue with drm related initializations.

Signed-off-by: Ajay Kumar <ajaykumar.rs@samsung.com>
Acked-by: Inki Dae <inki.dae@samsung.com>
Tested-by: Rahul Sharma <rahul.sharma@samsung.com>
Tested-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
Tested-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
Tested-by: Sjoerd Simons <sjoerd.simons@collabora.co.uk>
Signed-off-by: Thierry Reding <treding@nvidia.com>

2 files changed, 21 insertions, 13 deletions

diff --git a/include/drm/bridge/ptn3460.h b/include/drm/bridge/ptn3460.h
index ff62344..b11f8e1 100644
--- a/include/drm/bridge/ptn3460.h
+++ b/include/drm/bridge/ptn3460.h
@@ -15,6 +15,7 @@
 #define _DRM_BRIDGE_PTN3460_H_
 
 struct drm_device;
+struct drm_bridge;
 struct drm_encoder;
 struct i2c_client;
 struct device_node;
@@ -23,6 +24,9 @@ struct device_node;
 
 int ptn3460_init(struct drm_device *dev, struct drm_encoder *encoder,
 		struct i2c_client *client, struct device_node *node);
+
+void ptn3460_destroy(struct drm_bridge *bridge);
+
 #else
 
 static inline int ptn3460_init(struct drm_device *dev,
@@ -32,6 +36,10 @@ static inline int ptn3460_init(struct drm_device *dev,
 	return 0;
 }
 
+static inline void ptn3460_destroy(struct drm_bridge *bridge)
+{
+}
+
 #endif
 
 #endif
diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h
index 15bb762..920e21a 100644
--- a/include/drm/drm_crtc.h
+++ b/include/drm/drm_crtc.h
@@ -868,15 +868,16 @@ struct drm_plane {
 
 /**
  * struct drm_bridge_funcs - drm_bridge control functions
+ * @attach: Called during drm_bridge_attach
  * @mode_fixup: Try to fixup (or reject entirely) proposed mode for this bridge
  * @disable: Called right before encoder prepare, disables the bridge
  * @post_disable: Called right after encoder prepare, for lockstepped disable
  * @mode_set: Set this mode to the bridge
  * @pre_enable: Called right before encoder commit, for lockstepped commit
  * @enable: Called right after encoder commit, enables the bridge
- * @destroy: make object go away
  */
 struct drm_bridge_funcs {
+	int (*attach)(struct drm_bridge *bridge);
 	bool (*mode_fixup)(struct drm_bridge *bridge,
 			   const struct drm_display_mode *mode,
 			   struct drm_display_mode *adjusted_mode);
@@ -887,22 +888,24 @@ struct drm_bridge_funcs {
 			 struct drm_display_mode *adjusted_mode);
 	void (*pre_enable)(struct drm_bridge *bridge);
 	void (*enable)(struct drm_bridge *bridge);
-	void (*destroy)(struct drm_bridge *bridge);
 };
 
 /**
  * struct drm_bridge - central DRM bridge control structure
  * @dev: DRM device this bridge belongs to
- * @head: list management
+ * @of_node: device node pointer to the bridge
+ * @list: to keep track of all added bridges
  * @base: base mode object
  * @funcs: control functions
  * @driver_private: pointer to the bridge driver's internal context
  */
 struct drm_bridge {
 	struct drm_device *dev;
-	struct list_head head;
-
-	struct drm_mode_object base;
+	struct drm_encoder *encoder;
+#ifdef CONFIG_OF
+	struct device_node *of_node;
+#endif
+	struct list_head list;
 
 	const struct drm_bridge_funcs *funcs;
 	void *driver_private;
@@ -1007,7 +1010,6 @@ struct drm_mode_group {
 	uint32_t num_crtcs;
 	uint32_t num_encoders;
 	uint32_t num_connectors;
-	uint32_t num_bridges;
 
 	/* list of object IDs for this group */
 	uint32_t *id_list;
@@ -1026,8 +1028,6 @@ struct drm_mode_group {
  * @fb_list: list of framebuffers available
  * @num_connector: number of connectors on this device
  * @connector_list: list of connector objects
- * @num_bridge: number of bridges on this device
- * @bridge_list: list of bridge objects
  * @num_encoder: number of encoders on this device
  * @encoder_list: list of encoder objects
  * @num_overlay_plane: number of overlay planes on this device
@@ -1072,8 +1072,6 @@ struct drm_mode_config {
 
 	int num_connector;
 	struct list_head connector_list;
-	int num_bridge;
-	struct list_head bridge_list;
 	int num_encoder;
 	struct list_head encoder_list;
 
@@ -1222,8 +1220,10 @@ extern unsigned int drm_connector_index(struct drm_connector *connector);
 /* helper to unplug all connectors from sysfs for device */
 extern void drm_connector_unplug_all(struct drm_device *dev);
 
-extern int drm_bridge_init(struct drm_device *dev, struct drm_bridge *bridge);
-extern void drm_bridge_cleanup(struct drm_bridge *bridge);
+extern int drm_bridge_add(struct drm_bridge *bridge);
+extern void drm_bridge_remove(struct drm_bridge *bridge);
+extern struct drm_bridge *of_drm_find_bridge(struct device_node *np);
+extern int drm_bridge_attach(struct drm_device *dev, struct drm_bridge *bridge);
 
 extern int drm_encoder_init(struct drm_device *dev,
 			    struct drm_encoder *encoder,