[PATCH RFC 10/19] drm/bridge: Add a drm_bridge_state object

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One of the last remaining object to not have its atomic state.

This is being motivated by our attempt to support runtime bus-format
negotiation between elements of the bridge chain.
This patch just paves the road for such a feature by adding a new
drm_bridge_state object inheriting from drm_private_obj so we can
re-use some of the state initialization/tracking logic.

Signed-off-by: Boris Brezillon <boris.brezillon@xxxxxxxxxxxxx>
---
 drivers/gpu/drm/drm_atomic.c        |  40 ++++++++
 drivers/gpu/drm/drm_atomic_helper.c |  18 ++++
 drivers/gpu/drm/drm_bridge.c        | 141 +++++++++++++++++++++++++++-
 include/drm/drm_atomic.h            |   3 +
 include/drm/drm_bridge.h            |  99 +++++++++++++++++++
 5 files changed, 296 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/drm_atomic.c b/drivers/gpu/drm/drm_atomic.c
index 419381abbdd1..ed6fd3e31b56 100644
--- a/drivers/gpu/drm/drm_atomic.c
+++ b/drivers/gpu/drm/drm_atomic.c
@@ -30,6 +30,7 @@
 
 #include <drm/drm_atomic.h>
 #include <drm/drm_atomic_uapi.h>
+#include <drm/drm_bridge.h>
 #include <drm/drm_debugfs.h>
 #include <drm/drm_device.h>
 #include <drm/drm_drv.h>
@@ -1010,6 +1011,45 @@ static void drm_atomic_connector_print_state(struct drm_printer *p,
 		connector->funcs->atomic_print_state(p, state);
 }
 
+/**
+ * drm_atomic_add_encoder_bridges - add bridges attached to an encoder
+ * @state: atomic state
+ * @encoder: DRM encoder
+ *
+ * This function adds all bridges attached to @encoder. This is needed to add
+ * bridge states to @state and make them available when
+ * &bridge_funcs.atomic_{check,pre_enable,enable,disable_post_disable}() are
+ * called
+ *
+ * Returns:
+ * 0 on success or can fail with -EDEADLK or -ENOMEM. When the error is EDEADLK
+ * then the w/w mutex code has detected a deadlock and the entire atomic
+ * sequence must be restarted. All other errors are fatal.
+ */
+int
+drm_atomic_add_encoder_bridges(struct drm_atomic_state *state,
+			       struct drm_encoder *encoder)
+{
+	struct drm_bridge_state *bridge_state;
+	struct drm_bridge *bridge;
+
+	if (!encoder)
+		return 0;
+
+	DRM_DEBUG_ATOMIC("Adding all bridges for [encoder:%d:%s] to %p\n",
+			 encoder->base.id, encoder->name, state);
+
+	for (bridge = drm_bridge_chain_get_first_bridge(encoder); bridge;
+	     bridge = drm_bridge_chain_get_next_bridge(bridge)) {
+		bridge_state = drm_atomic_get_bridge_state(state, bridge);
+		if (IS_ERR(bridge_state))
+			return PTR_ERR(bridge_state);
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL(drm_atomic_add_encoder_bridges);
+
 /**
  * drm_atomic_add_affected_connectors - add connectors for crtc
  * @state: atomic state
diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
index 0deb54099570..e76ec9648b6f 100644
--- a/drivers/gpu/drm/drm_atomic_helper.c
+++ b/drivers/gpu/drm/drm_atomic_helper.c
@@ -736,6 +736,24 @@ drm_atomic_helper_check_modeset(struct drm_device *dev,
 			return ret;
 	}
 
+	/*
+	 * Iterate over all connectors again, and add all affected bridges to
+	 * the state.
+	 */
+	for_each_oldnew_connector_in_state(state, connector, old_connector_state, new_connector_state, i) {
+		struct drm_encoder *encoder;
+
+		encoder = old_connector_state->best_encoder;
+		ret = drm_atomic_add_encoder_bridges(state, encoder);
+		if (ret)
+			return ret;
+
+		encoder = new_connector_state->best_encoder;
+		ret = drm_atomic_add_encoder_bridges(state, encoder);
+		if (ret)
+			return ret;
+	}
+
 	ret = mode_valid(state);
 	if (ret)
 		return ret;
diff --git a/drivers/gpu/drm/drm_bridge.c b/drivers/gpu/drm/drm_bridge.c
index ed2410f49581..0280da6be1e6 100644
--- a/drivers/gpu/drm/drm_bridge.c
+++ b/drivers/gpu/drm/drm_bridge.c
@@ -89,6 +89,38 @@ void drm_bridge_remove(struct drm_bridge *bridge)
 }
 EXPORT_SYMBOL(drm_bridge_remove);
 
+static struct drm_private_state *
+drm_bridge_atomic_duplicate_priv_state(struct drm_private_obj *obj)
+{
+	struct drm_bridge *bridge = drm_priv_to_bridge(obj);
+	struct drm_bridge_state *state;
+
+	if (bridge->funcs->atomic_duplicate_state)
+		state = bridge->funcs->atomic_duplicate_state(bridge);
+	else
+		state = drm_atomic_helper_duplicate_bridge_state(bridge);
+
+	return &state->base;
+}
+
+static void
+drm_bridge_atomic_destroy_priv_state(struct drm_private_obj *obj,
+                                     struct drm_private_state *s)
+{
+	struct drm_bridge_state *state = drm_priv_to_bridge_state(s);
+	struct drm_bridge *bridge = drm_priv_to_bridge(obj);
+
+	if (bridge->funcs->atomic_destroy_state)
+		bridge->funcs->atomic_destroy_state(bridge, state);
+	else
+		drm_atomic_helper_destroy_bridge_state(bridge, state);
+}
+
+static const struct drm_private_state_funcs drm_bridge_priv_state_funcs = {
+	.atomic_duplicate_state = drm_bridge_atomic_duplicate_priv_state,
+	.atomic_destroy_state = drm_bridge_atomic_destroy_priv_state,
+};
+
 /**
  * drm_bridge_attach - attach the bridge to an encoder's chain
  *
@@ -114,6 +146,7 @@ EXPORT_SYMBOL(drm_bridge_remove);
 int drm_bridge_attach(struct drm_encoder *encoder, struct drm_bridge *bridge,
 		      struct drm_bridge *previous)
 {
+	struct drm_bridge_state *state;
 	LIST_HEAD(tmp_list);
 	int ret;
 
@@ -132,19 +165,39 @@ int drm_bridge_attach(struct drm_encoder *encoder, struct drm_bridge *bridge,
 
 	if (bridge->funcs->attach) {
 		ret = bridge->funcs->attach(bridge);
-		if (ret < 0) {
-			bridge->dev = NULL;
-			bridge->encoder = NULL;
-			return ret;
-		}
+		if (ret < 0)
+			goto err_reset_bridge;
 	}
 
+	if (bridge->funcs->atomic_duplicate_state)
+		state = bridge->funcs->atomic_duplicate_state(bridge);
+	else
+		state = drm_atomic_helper_duplicate_bridge_state(bridge);
+
+	if (!state) {
+		ret = -ENOMEM;
+		goto err_detach_bridge;
+	}
+
+	drm_atomic_private_obj_init(bridge->dev, &bridge->base,
+				    &state->base,
+				    &drm_bridge_priv_state_funcs);
+
 	if (previous)
 		list_splice(&tmp_list, &previous->chain_node);
 	else
 		list_splice(&tmp_list, &encoder->bridge_chain);
 
 	return 0;
+
+err_detach_bridge:
+	if (bridge->funcs->detach)
+		bridge->funcs->detach(bridge);
+
+err_reset_bridge:
+	bridge->dev = NULL;
+	bridge->encoder = NULL;
+	return ret;
 }
 EXPORT_SYMBOL(drm_bridge_attach);
 
@@ -156,6 +209,8 @@ void drm_bridge_detach(struct drm_bridge *bridge)
 	if (WARN_ON(!bridge->dev))
 		return;
 
+	drm_atomic_private_obj_fini(&bridge->base);
+
 	if (bridge->funcs->detach)
 		bridge->funcs->detach(bridge);
 
@@ -495,6 +550,82 @@ void drm_atomic_bridge_chain_enable(struct drm_encoder *encoder,
 }
 EXPORT_SYMBOL(drm_atomic_bridge_chain_enable);
 
+/**
+ * drm_atomic_helper_init_bridge_state() - Initializes a bridge state
+ * @bridge this state is referring to
+ * @state: bridge state to initialize
+ *
+ * For now it's just a memset(0) plus a state->bridge assignment. Might
+ * be extended in the future.
+ */
+void drm_atomic_helper_init_bridge_state(struct drm_bridge *bridge,
+					 struct drm_bridge_state *state)
+{
+	memset(state, 0, sizeof(*state));
+	state->bridge = bridge;
+}
+EXPORT_SYMBOL(drm_atomic_helper_init_bridge_state);
+
+/**
+ * drm_atomic_helper_copy_bridge_state() - Copy the content of a bridge state
+ * @bridge: bridge the old and new state are referring to
+ * @old: previous bridge state to copy from
+ * @new: new bridge state to copy to
+ *
+ * Should be used by custom &drm_bridge_funcs.atomic_duplicate() implementation
+ * to copy the previous state into the new object.
+ */
+void drm_atomic_helper_copy_bridge_state(struct drm_bridge *bridge,
+					 const struct drm_bridge_state *old,
+					 struct drm_bridge_state *new)
+{
+	*new = *old;
+}
+EXPORT_SYMBOL(drm_atomic_helper_copy_bridge_state);
+
+/**
+ * drm_atomic_helper_duplicate_bridge_state() - Default duplicate state helper
+ * @bridge: bridge containing the state to duplicate
+ *
+ * Default implementation of &drm_bridge_funcs.atomic_duplicate().
+ *
+ * RETURNS:
+ * a valid state object or NULL if the allocation fails.
+ */
+struct drm_bridge_state *
+drm_atomic_helper_duplicate_bridge_state(struct drm_bridge *bridge)
+{
+	struct drm_bridge_state *old = NULL, *new;
+
+	new = kzalloc(sizeof(*new), GFP_KERNEL);
+	if (!new)
+		return NULL;
+
+	if (bridge->base.state) {
+		old = drm_priv_to_bridge_state(bridge->base.state);
+		drm_atomic_helper_copy_bridge_state(bridge, old, new);
+	} else {
+		drm_atomic_helper_init_bridge_state(bridge, new);
+	}
+
+	return new;
+}
+EXPORT_SYMBOL(drm_atomic_helper_duplicate_bridge_state);
+
+/**
+ * drm_atomic_helper_destroy_bridge_state() - Default destroy state helper
+ * @bridge: the bridge this state refers to
+ * @state: state object to destroy
+ *
+ * Just a simple kfree() for now.
+ */
+void drm_atomic_helper_destroy_bridge_state(struct drm_bridge *bridge,
+					    struct drm_bridge_state *state)
+{
+	kfree(state);
+}
+EXPORT_SYMBOL(drm_atomic_helper_destroy_bridge_state);
+
 #ifdef CONFIG_OF
 /**
  * of_drm_find_bridge - find the bridge corresponding to the device node in
diff --git a/include/drm/drm_atomic.h b/include/drm/drm_atomic.h
index 927e1205d7aa..5ee25fd51e80 100644
--- a/include/drm/drm_atomic.h
+++ b/include/drm/drm_atomic.h
@@ -660,6 +660,9 @@ __drm_atomic_get_current_plane_state(struct drm_atomic_state *state,
 	return plane->state;
 }
 
+int __must_check
+drm_atomic_add_encoder_bridges(struct drm_atomic_state *state,
+                               struct drm_encoder *encoder);
 int __must_check
 drm_atomic_add_affected_connectors(struct drm_atomic_state *state,
 				   struct drm_crtc *crtc);
diff --git a/include/drm/drm_bridge.h b/include/drm/drm_bridge.h
index f40181274ed7..8ca25d266d0c 100644
--- a/include/drm/drm_bridge.h
+++ b/include/drm/drm_bridge.h
@@ -25,6 +25,7 @@
 
 #include <linux/list.h>
 #include <linux/ctype.h>
+#include <drm/drm_atomic.h>
 #include <drm/drm_mode_object.h>
 #include <drm/drm_modes.h>
 
@@ -32,6 +33,23 @@ struct drm_bridge;
 struct drm_bridge_timings;
 struct drm_panel;
 
+/**
+ * struct drm_bridge_state - Atomic bridge state object
+ * @base: inherit from &drm_private_state
+ * @bridge: the bridge this state refers to
+ */
+struct drm_bridge_state {
+	struct drm_private_state base;
+
+	struct drm_bridge *bridge;
+};
+
+static inline struct drm_bridge_state *
+drm_priv_to_bridge_state(struct drm_private_state *priv)
+{
+	return container_of(priv, struct drm_bridge_state, base);
+}
+
 /**
  * struct drm_bridge_funcs - drm_bridge control functions
  */
@@ -337,6 +355,30 @@ struct drm_bridge_funcs {
 	 */
 	void (*atomic_post_disable)(struct drm_bridge *bridge,
 				    struct drm_atomic_state *state);
+
+	/**
+	 * @atomic_duplicate_state:
+	 *
+	 * Duplicate the current bridge state object.
+	 *
+	 * Note that this function can be called when current bridge state is
+	 * NULL. In this case, implementations should either implement HW
+	 * readback or initialize the state with sensible default values.
+	 *
+	 * RETURNS:
+	 * A valid drm_bridge_state object or NULL if the allocation fails.
+	 */
+	struct drm_bridge_state *(*atomic_duplicate_state)(struct drm_bridge *bridge);
+
+	/**
+	 * @atomic_duplicate_state:
+	 *
+	 * Destroy a bridge state object previously allocated by
+	 * &drm_bridge_funcs.atomic_duplicate_state() or
+	 * &drm_bridge_funcs.atomic_get_initial_state().
+	 */
+	void (*atomic_destroy_state)(struct drm_bridge *bridge,
+				     struct drm_bridge_state *state);
 };
 
 /**
@@ -379,6 +421,8 @@ struct drm_bridge_timings {
  * struct drm_bridge - central DRM bridge control structure
  */
 struct drm_bridge {
+	/** @base: inherit from &drm_private_object */
+	struct drm_private_obj base;
 	/** @dev: DRM device this bridge belongs to */
 	struct drm_device *dev;
 	/** @encoder: encoder to which this bridge is connected */
@@ -403,6 +447,12 @@ struct drm_bridge {
 	void *driver_private;
 };
 
+static inline struct drm_bridge *
+drm_priv_to_bridge(struct drm_private_obj *priv)
+{
+	return container_of(priv, struct drm_bridge, base);
+}
+
 void drm_bridge_add(struct drm_bridge *bridge);
 void drm_bridge_remove(struct drm_bridge *bridge);
 struct drm_bridge *of_drm_find_bridge(struct device_node *np);
@@ -438,6 +488,55 @@ void drm_atomic_bridge_chain_pre_enable(struct drm_encoder *encoder,
 void drm_atomic_bridge_chain_enable(struct drm_encoder *encoder,
 				    struct drm_atomic_state *state);
 
+void drm_atomic_helper_init_bridge_state(struct drm_bridge *bridge,
+					 struct drm_bridge_state *state);
+void drm_atomic_helper_copy_bridge_state(struct drm_bridge *bridge,
+					 const struct drm_bridge_state *old,
+					 struct drm_bridge_state *new);
+struct drm_bridge_state *
+drm_atomic_helper_duplicate_bridge_state(struct drm_bridge *bridge);
+void drm_atomic_helper_destroy_bridge_state(struct drm_bridge *bridge,
+					    struct drm_bridge_state *state);
+
+static inline struct drm_bridge_state *
+drm_atomic_get_bridge_state(struct drm_atomic_state *state,
+			    struct drm_bridge *bridge)
+{
+	struct drm_private_state *obj_state;
+
+	obj_state = drm_atomic_get_private_obj_state(state, &bridge->base);
+	if (!obj_state)
+		return NULL;
+
+	return drm_priv_to_bridge_state(obj_state);
+}
+
+static inline struct drm_bridge_state *
+drm_atomic_get_old_bridge_state(struct drm_atomic_state *state,
+				struct drm_bridge *bridge)
+{
+	struct drm_private_state *obj_state;
+
+	obj_state = drm_atomic_get_old_private_obj_state(state, &bridge->base);
+	if (!obj_state)
+		return NULL;
+
+	return drm_priv_to_bridge_state(obj_state);
+}
+
+static inline struct drm_bridge_state *
+drm_atomic_get_new_bridge_state(struct drm_atomic_state *state,
+				struct drm_bridge *bridge)
+{
+	struct drm_private_state *obj_state;
+
+	obj_state = drm_atomic_get_new_private_obj_state(state, &bridge->base);
+	if (!obj_state)
+		return NULL;
+
+	return drm_priv_to_bridge_state(obj_state);
+}
+
 #ifdef CONFIG_DRM_PANEL_BRIDGE
 struct drm_bridge *drm_panel_bridge_add(struct drm_panel *panel,
 					u32 connector_type);
-- 
2.21.0

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