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

Hi Boris,

Thank you for the patch.

On Thu, Aug 08, 2019 at 05:11:41PM +0200, Boris Brezillon wrote:

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@collabora.com

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)) {
  

Would a for_each_bridge() macro make sense ? I'd implement it on top of list_for_each_entry() to make it simple.

• 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

s/Initializes/Initialize/

• • @bridge this state is referring to

Did you mean

* @bridge: the 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);

Other objects don't export a state init function helper, but state reset and state duplicate helpers. Is there a reason to depart from that model ? Same for the copy helper below.

+/**

• • 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.
  

Related to the question above, shouldn't we have a reset state operation instead ?

• *
  

• * 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);