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 <[e-mail]>
Acked-by: Inki Dae <[e-mail]>
Tested-by: Rahul Sharma <[e-mail]>
Tested-by: Javier Martinez Canillas <[e-mail]>
Tested-by: Gustavo Padovan <[e-mail]>
Tested-by: Sjoerd Simons <[e-mail]>
Signed-off-by: Thierry Reding <[e-mail]>

drivers/gpu/drm/Makefile

···
 		drm_info.o drm_debugfs.o drm_encoder_slave.o \
 		drm_trace_points.o drm_global.o drm_prime.o \
 		drm_rect.o drm_vma_manager.o drm_flip_work.o \
-		drm_modeset_lock.o drm_atomic.o
+		drm_modeset_lock.o drm_atomic.o drm_bridge.o
 
 drm-$(CONFIG_COMPAT) += drm_ioc32.o
 drm-$(CONFIG_DRM_GEM_CMA_HELPER) += drm_gem_cma_helper.o

drivers/gpu/drm/bridge/ptn3460.c

···
 {
 }
 
-static void ptn3460_bridge_destroy(struct drm_bridge *bridge)
-{
-	struct ptn3460_bridge *ptn_bridge = bridge_to_ptn3460(bridge);
-
-	drm_bridge_cleanup(bridge);
-	if (gpio_is_valid(ptn_bridge->gpio_pd_n))
-		gpio_free(ptn_bridge->gpio_pd_n);
-	if (gpio_is_valid(ptn_bridge->gpio_rst_n))
-		gpio_free(ptn_bridge->gpio_rst_n);
-	/* Nothing else to free, we've got devm allocated memory */
-}
-
 static struct drm_bridge_funcs ptn3460_bridge_funcs = {
 	.pre_enable = ptn3460_pre_enable,
 	.enable = ptn3460_enable,
 	.disable = ptn3460_disable,
 	.post_disable = ptn3460_post_disable,
-	.destroy = ptn3460_bridge_destroy,
 };
 
 static int ptn3460_get_modes(struct drm_connector *connector)
···
 	}
 
 	ptn_bridge->bridge.funcs = &ptn3460_bridge_funcs;
-	ret = drm_bridge_init(dev, &ptn_bridge->bridge);
+	ret = drm_bridge_attach(dev, &ptn_bridge->bridge);
 	if (ret) {
 		DRM_ERROR("Failed to initialize bridge with drm\n");
 		goto err;
···
 	return ret;
 }
 EXPORT_SYMBOL(ptn3460_init);
+
+void ptn3460_destroy(struct drm_bridge *bridge)
+{
+	struct ptn3460_bridge *ptn_bridge = bridge->driver_private;
+
+	if (gpio_is_valid(ptn_bridge->gpio_pd_n))
+		gpio_free(ptn_bridge->gpio_pd_n);
+	if (gpio_is_valid(ptn_bridge->gpio_rst_n))
+		gpio_free(ptn_bridge->gpio_rst_n);
+	/* Nothing else to free, we've got devm allocated memory */
+}
+EXPORT_SYMBOL(ptn3460_destroy);

drivers/gpu/drm/drm_bridge.c

···
+/*
+ * Copyright (c) 2014 Samsung Electronics Co., Ltd
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sub license,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the
+ * next paragraph) shall be included in all copies or substantial portions
+ * of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ */
+
+#include <linux/err.h>
+#include <linux/module.h>
+
+#include <drm/drm_crtc.h>
+
+#include "drm/drmP.h"
+
+static DEFINE_MUTEX(bridge_lock);
+static LIST_HEAD(bridge_list);
+
+int drm_bridge_add(struct drm_bridge *bridge)
+{
+	mutex_lock(&bridge_lock);
+	list_add_tail(&bridge->list, &bridge_list);
+	mutex_unlock(&bridge_lock);
+
+	return 0;
+}
+EXPORT_SYMBOL(drm_bridge_add);
+
+void drm_bridge_remove(struct drm_bridge *bridge)
+{
+	mutex_lock(&bridge_lock);
+	list_del_init(&bridge->list);
+	mutex_unlock(&bridge_lock);
+}
+EXPORT_SYMBOL(drm_bridge_remove);
+
+extern int drm_bridge_attach(struct drm_device *dev, struct drm_bridge *bridge)
+{
+	if (!dev || !bridge)
+		return -EINVAL;
+
+	if (bridge->dev)
+		return -EBUSY;
+
+	bridge->dev = dev;
+
+	if (bridge->funcs->attach)
+		return bridge->funcs->attach(bridge);
+
+	return 0;
+}
+EXPORT_SYMBOL(drm_bridge_attach);
+
+#ifdef CONFIG_OF
+struct drm_bridge *of_drm_find_bridge(struct device_node *np)
+{
+	struct drm_bridge *bridge;
+
+	mutex_lock(&bridge_lock);
+
+	list_for_each_entry(bridge, &bridge_list, list) {
+		if (bridge->of_node == np) {
+			mutex_unlock(&bridge_lock);
+			return bridge;
+		}
+	}
+
+	mutex_unlock(&bridge_lock);
+	return NULL;
+}
+EXPORT_SYMBOL(of_drm_find_bridge);
+#endif
+
+MODULE_AUTHOR("Ajay Kumar <[e-mail]>");
+MODULE_DESCRIPTION("DRM bridge infrastructure");
+MODULE_LICENSE("GPL and additional rights");

drivers/gpu/drm/drm_crtc.c

···
 EXPORT_SYMBOL(drm_connector_unplug_all);
 
 /**
- * drm_bridge_init - initialize a drm transcoder/bridge
- * @dev: drm device
- * @bridge: transcoder/bridge to set up
- *
- * Initialises a preallocated bridge. Bridges should be
- * subclassed as part of driver connector objects.
- *
- * Returns:
- * Zero on success, error code on failure.
- */
-int drm_bridge_init(struct drm_device *dev, struct drm_bridge *bridge)
-{
-	int ret;
-
-	drm_modeset_lock_all(dev);
-
-	ret = drm_mode_object_get(dev, &bridge->base, DRM_MODE_OBJECT_BRIDGE);
-	if (ret)
-		goto out;
-
-	bridge->dev = dev;
-
-	list_add_tail(&bridge->head, &dev->mode_config.bridge_list);
-	dev->mode_config.num_bridge++;
-
- out:
-	drm_modeset_unlock_all(dev);
-	return ret;
-}
-EXPORT_SYMBOL(drm_bridge_init);
-
-/**
- * drm_bridge_cleanup - cleans up an initialised bridge
- * @bridge: bridge to cleanup
- *
- * Cleans up the bridge but doesn't free the object.
- */
-void drm_bridge_cleanup(struct drm_bridge *bridge)
-{
-	struct drm_device *dev = bridge->dev;
-
-	drm_modeset_lock_all(dev);
-	drm_mode_object_put(dev, &bridge->base);
-	list_del(&bridge->head);
-	dev->mode_config.num_bridge--;
-	drm_modeset_unlock_all(dev);
-
-	memset(bridge, 0, sizeof(*bridge));
-}
-EXPORT_SYMBOL(drm_bridge_cleanup);
-
-/**
  * drm_encoder_init - Init a preallocated encoder
  * @dev: drm device
  * @encoder: the encoder to init
···
 	total_objects += dev->mode_config.num_crtc;
 	total_objects += dev->mode_config.num_connector;
 	total_objects += dev->mode_config.num_encoder;
-	total_objects += dev->mode_config.num_bridge;
 
 	group->id_list = kcalloc(total_objects, sizeof(uint32_t), GFP_KERNEL);
 	if (!group->id_list)
···
 	group->num_crtcs = 0;
 	group->num_connectors = 0;
 	group->num_encoders = 0;
-	group->num_bridges = 0;
 	return 0;
 }
 
···
 	struct drm_crtc *crtc;
 	struct drm_encoder *encoder;
 	struct drm_connector *connector;
-	struct drm_bridge *bridge;
 	int ret;
 
 	ret = drm_mode_group_init(dev, group);
···
 	list_for_each_entry(connector, &dev->mode_config.connector_list, head)
 		group->id_list[group->num_crtcs + group->num_encoders +
 			       group->num_connectors++] = connector->base.id;
-
-	list_for_each_entry(bridge, &dev->mode_config.bridge_list, head)
-		group->id_list[group->num_crtcs + group->num_encoders +
-			       group->num_connectors + group->num_bridges++] =
-					bridge->base.id;
 
 	return 0;
 }
···
 	INIT_LIST_HEAD(&dev->mode_config.fb_list);
 	INIT_LIST_HEAD(&dev->mode_config.crtc_list);
 	INIT_LIST_HEAD(&dev->mode_config.connector_list);
-	INIT_LIST_HEAD(&dev->mode_config.bridge_list);
 	INIT_LIST_HEAD(&dev->mode_config.encoder_list);
 	INIT_LIST_HEAD(&dev->mode_config.property_list);
 	INIT_LIST_HEAD(&dev->mode_config.property_blob_list);
···
 	struct drm_connector *connector, *ot;
 	struct drm_crtc *crtc, *ct;
 	struct drm_encoder *encoder, *enct;
-	struct drm_bridge *bridge, *brt;
 	struct drm_framebuffer *fb, *fbt;
 	struct drm_property *property, *pt;
 	struct drm_property_blob *blob, *bt;
···
 	list_for_each_entry_safe(encoder, enct, &dev->mode_config.encoder_list,
 				 head) {
 		encoder->funcs->destroy(encoder);
-	}
-
-	list_for_each_entry_safe(bridge, brt,
-				 &dev->mode_config.bridge_list, head) {
-		bridge->funcs->destroy(bridge);
 	}
 
 	list_for_each_entry_safe(connector, ot,

drivers/gpu/drm/msm/hdmi/hdmi.c

···
 	return 0;
 
 fail:
-	/* bridge/connector are normally destroyed by drm: */
+	/* bridge is normally destroyed by drm: */
 	if (hdmi->bridge) {
-		hdmi->bridge->funcs->destroy(hdmi->bridge);
+		hdmi_bridge_destroy(hdmi->bridge);
 		hdmi->bridge = NULL;
 	}
 	if (hdmi->connector) {

drivers/gpu/drm/msm/hdmi/hdmi.h

···
  */
 
 struct drm_bridge *hdmi_bridge_init(struct hdmi *hdmi);
+void hdmi_bridge_destroy(struct drm_bridge *bridge);
 
 /*
  * hdmi connector:

drivers/gpu/drm/msm/hdmi/hdmi_bridge.c

···
 };
 #define to_hdmi_bridge(x) container_of(x, struct hdmi_bridge, base)
 
-static void hdmi_bridge_destroy(struct drm_bridge *bridge)
+void hdmi_bridge_destroy(struct drm_bridge *bridge)
 {
 	struct hdmi_bridge *hdmi_bridge = to_hdmi_bridge(bridge);
-	drm_bridge_cleanup(bridge);
 	kfree(hdmi_bridge);
 }
 
···
 		.disable = hdmi_bridge_disable,
 		.post_disable = hdmi_bridge_post_disable,
 		.mode_set = hdmi_bridge_mode_set,
-		.destroy = hdmi_bridge_destroy,
 };
 
 
···
 	bridge = &hdmi_bridge->base;
 	bridge->funcs = &hdmi_bridge_funcs;
 
-	drm_bridge_init(hdmi->dev, bridge);
+	drm_bridge_attach(hdmi->dev, bridge);
 
 	return bridge;
 

drivers/gpu/drm/sti/sti_hda.c

···
 	/* do nothing */
 }
 
-static void sti_hda_brigde_destroy(struct drm_bridge *bridge)
-{
-	drm_bridge_cleanup(bridge);
-	kfree(bridge);
-}
-
 static const struct drm_bridge_funcs sti_hda_bridge_funcs = {
 	.pre_enable = sti_hda_pre_enable,
 	.enable = sti_hda_bridge_nope,
 	.disable = sti_hda_disable,
 	.post_disable = sti_hda_bridge_nope,
 	.mode_set = sti_hda_set_mode,
-	.destroy = sti_hda_brigde_destroy,
 };
 
 static int sti_hda_connector_get_modes(struct drm_connector *connector)
···
 
 	bridge->driver_private = hda;
 	bridge->funcs = &sti_hda_bridge_funcs;
-	drm_bridge_init(drm_dev, bridge);
+	drm_bridge_attach(drm_dev, bridge);
 
 	encoder->bridge = bridge;
 	connector->encoder = encoder;
···
 err_sysfs:
 	drm_connector_unregister(drm_connector);
 err_connector:
-	drm_bridge_cleanup(bridge);
 	drm_connector_cleanup(drm_connector);
 	return -EINVAL;
 }

drivers/gpu/drm/sti/sti_hdmi.c

···
 	/* do nothing */
 }
 
-static void sti_hdmi_brigde_destroy(struct drm_bridge *bridge)
-{
-	drm_bridge_cleanup(bridge);
-	kfree(bridge);
-}
-
 static const struct drm_bridge_funcs sti_hdmi_bridge_funcs = {
 	.pre_enable = sti_hdmi_pre_enable,
 	.enable = sti_hdmi_bridge_nope,
 	.disable = sti_hdmi_disable,
 	.post_disable = sti_hdmi_bridge_nope,
 	.mode_set = sti_hdmi_set_mode,
-	.destroy = sti_hdmi_brigde_destroy,
 };
 
 static int sti_hdmi_connector_get_modes(struct drm_connector *connector)
···
 
 	bridge->driver_private = hdmi;
 	bridge->funcs = &sti_hdmi_bridge_funcs;
-	drm_bridge_init(drm_dev, bridge);
+	drm_bridge_attach(drm_dev, bridge);
 
 	encoder->bridge = bridge;
 	connector->encoder = encoder;
···
 err_sysfs:
 	drm_connector_unregister(drm_connector);
 err_connector:
-	drm_bridge_cleanup(bridge);
 	drm_connector_cleanup(drm_connector);
 err_adapt:
 	put_device(&hdmi->ddc_adapt->dev);

include/drm/bridge/ptn3460.h

···
 #define _DRM_BRIDGE_PTN3460_H_
 
 struct drm_device;
+struct drm_bridge;
 struct drm_encoder;
 struct i2c_client;
 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,
···
 		struct device_node *node)
 {
 	return 0;
+}
+
+static inline void ptn3460_destroy(struct drm_bridge *bridge)
+{
 }
 
 #endif

include/drm/drm_crtc.h

···
 
 /**
  * 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);
···
 			 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;
···
 	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;
···
  * @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
···
 
 	int num_connector;
 	struct list_head connector_list;
-	int num_bridge;
-	struct list_head bridge_list;
 	int num_encoder;
 	struct list_head encoder_list;
 
···
 /* 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,