Re: [PATCH v4 08/11] drm/bridge: Add a drm_bridge_state object

Hi Boris,

Thank you for the patch.

On Tue, Dec 03, 2019 at 03:15:12PM +0100, Boris Brezillon wrote:

One of the last remaining objects 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 existing state initialization/tracking logic.

Signed-off-by: Boris Brezillon boris.brezillon@collabora.com Reviewed-by: Neil Armstrong narmstrong@baylibre.com

---

Changes in v4:

• Fix the doc
• Kill default helpers (inlined)

I liked the default helpers, inlining their content makes the code more difficult to follow in my opinion. I will however not push back if you prefer not to have them.

• Fix drm_atomic_get_bridge_state() to check for an ERR_PTR()
• Add Neil's R-b

Changes in v3:

• None

Changes in v2:

• Use drm_for_each_bridge_in_chain()
• Rename helpers to be more consistent with the rest of the DRM API
• Improve/fix the doc

---

drivers/gpu/drm/drm_atomic.c | 39 +++++++++ drivers/gpu/drm/drm_atomic_helper.c | 20 +++++ drivers/gpu/drm/drm_bridge.c | 118 ++++++++++++++++++++++++++-- include/drm/drm_atomic.h | 3 + include/drm/drm_bridge.h | 116 +++++++++++++++++++++++++++ 5 files changed, 290 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/drm_atomic.c b/drivers/gpu/drm/drm_atomic.c index 14aeaf736321..02f8034f5240 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> @@ -1015,6 +1016,44 @@ 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);
  

• drm_for_each_bridge_in_chain(encoder, 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 29c3115bf9e2..e2f7f336a2d2 100644 --- a/drivers/gpu/drm/drm_atomic_helper.c +++ b/drivers/gpu/drm/drm_atomic_helper.c @@ -730,6 +730,26 @@ 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 b6517b4fa3d1..bf5a2243a115 100644 --- a/drivers/gpu/drm/drm_bridge.c +++ b/drivers/gpu/drm/drm_bridge.c @@ -25,6 +25,7 @@ #include <linux/module.h> #include <linux/mutex.h>

+#include <drm/drm_atomic_state_helper.h> #include <drm/drm_bridge.h> #include <drm/drm_encoder.h>

@@ -89,6 +90,48 @@ 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);
  

• return state ? &state->base : NULL;
  

• }
• if (WARN_ON(!bridge->base.state))

• return NULL;
  

• state = kzalloc(sizeof(*state), GFP_KERNEL);
• if (!state)

• return NULL;
  

• __drm_atomic_helper_bridge_duplicate_state(bridge, state);
• 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

• kfree(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 +157,7 @@ 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; int ret;

  if (!encoder || !bridge)

@@ -135,15 +179,40 @@ int drm_bridge_attach(struct drm_encoder *encoder, struct drm_bridge *bridge,

if (bridge->funcs->attach) { ret = bridge->funcs->attach(bridge);

• if (ret < 0) {
  

• 	list_del(&bridge->chain_node);
  

• 	bridge->dev = NULL;
  

• 	bridge->encoder = NULL;
  

• 	return ret;
  

• }
  

• if (ret < 0)
  

• 	goto err_reset_bridge;
  

  }

• if (bridge->funcs->atomic_reset) {

• state = bridge->funcs->atomic_reset(bridge);
  

• } else {

• state = kzalloc(sizeof(*state), GFP_KERNEL);
  

• if (state)
  

• 	__drm_atomic_helper_bridge_reset(bridge, state);
  

• else
  

• 	state = ERR_PTR(-ENOMEM);
  

• }

• if (IS_ERR(state)) {

• ret = PTR_ERR(state);
  

• goto err_detach_bridge;
  

• }

• drm_atomic_private_obj_init(bridge->dev, &bridge->base,

• 		    &state->base,
  

• 		    &drm_bridge_priv_state_funcs);
  

• return 0;

+err_detach_bridge:

• if (bridge->funcs->detach)

• bridge->funcs->detach(bridge);
  

+err_reset_bridge:

• bridge->dev = NULL;
• bridge->encoder = NULL;
• list_del(&bridge->chain_node);
• return ret;

} EXPORT_SYMBOL(drm_bridge_attach);

@@ -155,6 +224,8 @@ 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);

@@ -516,6 +587,41 @@ void drm_atomic_bridge_chain_enable(struct drm_bridge *bridge, } EXPORT_SYMBOL(drm_atomic_bridge_chain_enable);

+/**

• • __drm_atomic_helper_bridge_reset() - Initialize a bridge state to its

• • 			default
    

• • @bridge: the bridge this state is refers to
• • @state: bridge state to initialize
• • Initialize the bridge state to default values. This is meant to be* called

s/be*/be/

Reviewed-by: Laurent Pinchart laurent.pinchart@ideasonboard.com

• • by the bridge &drm_plane_funcs.reset hook for bridges that subclass the
• • bridge state.
• */

+void __drm_atomic_helper_bridge_reset(struct drm_bridge *bridge,

• 		      struct drm_bridge_state *state)
  

+{

• memset(state, 0, sizeof(*state));
• state->bridge = bridge;

+} +EXPORT_SYMBOL(__drm_atomic_helper_bridge_reset);

+/**

• • __drm_atomic_helper_bridge_duplicate_state() - Copy atomic bridge state
• • @bridge: bridge object
• • @state: atomic bridge state
• • Copies atomic state from a bridge's current state and resets inferred values.
• • This is useful for drivers that subclass the bridge state.
• */

+void __drm_atomic_helper_bridge_duplicate_state(struct drm_bridge *bridge,

• 				struct drm_bridge_state *state)
  

+{

• __drm_atomic_helper_private_obj_duplicate_state(&bridge->base,

• 					&state->base);
  

• state->bridge = bridge;

+} +EXPORT_SYMBOL(__drm_atomic_helper_bridge_duplicate_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 b6c73fd9f55a..e08582773d6c 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 d7d714023050..db5fc18d49bd 100644 --- a/include/drm/drm_bridge.h +++ b/include/drm/drm_bridge.h @@ -25,6 +25,8 @@

#include <linux/list.h> #include <linux/ctype.h>

+#include <drm/drm_atomic.h> #include <drm/drm_encoder.h> #include <drm/drm_mode_object.h> #include <drm/drm_modes.h> @@ -33,6 +35,23 @@ 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

*/ @@ -338,6 +357,49 @@ struct drm_bridge_funcs { */ void (*atomic_post_disable)(struct drm_bridge *bridge, struct drm_atomic_state *old_state);

• /**

• * @atomic_duplicate_state:
  

• *
  

• * Duplicate the current bridge state object (which is guaranteed to be
  

• * non-NULL).
  

• *
  

• * The atomic_duplicate_state() is optional. When not implemented the
  

• * core allocates a drm_bridge_state object and calls
  

• * &__drm_atomic_helper_bridge_duplicate_state() to initialize it.
  

• *
  

• * 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_destroy_state:
  

• *
  

• * Destroy a bridge state object previously allocated by
  

• * &drm_bridge_funcs.atomic_duplicate_state().
  

• *
  

• * The atomic_destroy_state hook is optional. When not implemented the
  

• * core calls kfree() on the state.
  

• */
  

• void (*atomic_destroy_state)(struct drm_bridge *bridge,

• 		     struct drm_bridge_state *state);
  

• /**

• * @atomic_reset:
  

• *
  

• * Reset the bridge to a predefined state (or retrieve its current
  

• * state) and return a &drm_bridge_state object matching this state.
  

• * This function is called at attach time.
  

• *
  

• * The atomic_reset hook is optional. When not implemented the core
  

• * allocates a new state and calls &__drm_atomic_helper_bridge_reset().
  

• *
  

• * RETURNS:
  

• * A valid drm_bridge_state object in case of success, an ERR_PTR()
  

• * giving the reason of the failure otherwise.
  

• */
  

• struct drm_bridge_state *(*atomic_reset)(struct drm_bridge *bridge);

};

/** @@ -380,6 +442,8 @@ 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 */

@@ -404,6 +468,12 @@ 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); @@ -491,6 +561,52 @@ void drm_atomic_bridge_chain_pre_enable(struct drm_bridge *bridge, void drm_atomic_bridge_chain_enable(struct drm_bridge *bridge, struct drm_atomic_state *state);

+void __drm_atomic_helper_bridge_reset(struct drm_bridge *bridge,

• 		      struct drm_bridge_state *state);
  

+struct drm_bridge_state * +drm_atomic_helper_bridge_reset(struct drm_bridge *bridge); +void __drm_atomic_helper_bridge_duplicate_state(struct drm_bridge *bridge,

• 				struct drm_bridge_state *new);
  

+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 (IS_ERR(obj_state))

• return ERR_CAST(obj_state);
  

• 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); struct drm_bridge *drm_panel_bridge_add_typed(struct drm_panel *panel, -- 2.23.0