42  * A bridge is always attached to a single &drm_encoder at a time, but can be
45  *     [ CRTC ---> ] Encoder ---> Bridge A ---> Bridge B
47  * Here, the output of the encoder feeds to bridge A, and that furthers feeds to
48  * bridge B. Bridge chains can be arbitrarily long, and shall be fully linear:
49  * Chaining multiple bridges to the output of a bridge, or the same bridge to
52  * Display drivers are responsible for linking encoders with the first bridge
53  * in the chains. This is done by acquiring the appropriate bridge with
56  * devm_drm_panel_bridge_add_typed()). Once acquired, the bridge shall be
59  * Bridges are responsible for linking themselves with the next bridge in the
81  * DRM bridge chain functions shall be called manually.
84  * the bridge chain. Display drivers may use the drm_bridge_connector_init()
86  * connector-related operations exposed by the bridge (see the overview
87  * documentation of bridge operations for more details).
99  * drm_bridge_add - add the given bridge to the global bridge list
101  * @bridge: bridge control structure
103 void drm_bridge_add(struct drm_bridge *bridge)  in drm_bridge_add()  argument
105 	mutex_init(&bridge->hpd_mutex);  in drm_bridge_add()
108 	list_add_tail(&bridge->list, &bridge_list);  in drm_bridge_add()
114  * drm_bridge_remove - remove the given bridge from the global bridge list
116  * @bridge: bridge control structure
118 void drm_bridge_remove(struct drm_bridge *bridge)  in drm_bridge_remove()  argument
121 	list_del_init(&bridge->list);  in drm_bridge_remove()
124 	mutex_destroy(&bridge->hpd_mutex);  in drm_bridge_remove()
131 	struct drm_bridge *bridge = drm_priv_to_bridge(obj);  in drm_bridge_atomic_duplicate_priv_state()  local
134 	state = bridge->funcs->atomic_duplicate_state(bridge);  in drm_bridge_atomic_duplicate_priv_state()
143 	struct drm_bridge *bridge = drm_priv_to_bridge(obj);  in drm_bridge_atomic_destroy_priv_state()  local
145 	bridge->funcs->atomic_destroy_state(bridge, state);  in drm_bridge_atomic_destroy_priv_state()
154  * drm_bridge_attach - attach the bridge to an encoder's chain
157  * @bridge: bridge to attach
158  * @previous: previous bridge in the chain (optional)
161  * Called by a kms driver to link the bridge to an encoder's chain. The previous
162  * argument specifies the previous bridge in the chain. If NULL, the bridge is
164  * previous bridge's output.
166  * If non-NULL the previous bridge must be already attached by a call to this
176 int drm_bridge_attach(struct drm_encoder *encoder, struct drm_bridge *bridge,  in drm_bridge_attach()  argument
182 	if (!encoder || !bridge)  in drm_bridge_attach()
188 	if (bridge->dev)  in drm_bridge_attach()
191 	bridge->dev = encoder->dev;  in drm_bridge_attach()
192 	bridge->encoder = encoder;  in drm_bridge_attach()
195 		list_add(&bridge->chain_node, &previous->chain_node);  in drm_bridge_attach()
197 		list_add(&bridge->chain_node, &encoder->bridge_chain);  in drm_bridge_attach()
199 	if (bridge->funcs->attach) {  in drm_bridge_attach()
200 		ret = bridge->funcs->attach(bridge, flags);  in drm_bridge_attach()
205 	if (bridge->funcs->atomic_reset) {  in drm_bridge_attach()
208 		state = bridge->funcs->atomic_reset(bridge);  in drm_bridge_attach()
214 		drm_atomic_private_obj_init(bridge->dev, &bridge->base,  in drm_bridge_attach()
222 	if (bridge->funcs->detach)  in drm_bridge_attach()
223 		bridge->funcs->detach(bridge);  in drm_bridge_attach()
226 	bridge->dev = NULL;  in drm_bridge_attach()
227 	bridge->encoder = NULL;  in drm_bridge_attach()
228 	list_del(&bridge->chain_node);  in drm_bridge_attach()
231 	DRM_ERROR("failed to attach bridge %pOF to encoder %s: %d\n",  in drm_bridge_attach()
232 		  bridge->of_node, encoder->name, ret);  in drm_bridge_attach()
234 	DRM_ERROR("failed to attach bridge to encoder %s: %d\n",  in drm_bridge_attach()
242 void drm_bridge_detach(struct drm_bridge *bridge)  in drm_bridge_detach()  argument
244 	if (WARN_ON(!bridge))  in drm_bridge_detach()
247 	if (WARN_ON(!bridge->dev))  in drm_bridge_detach()
250 	if (bridge->funcs->atomic_reset)  in drm_bridge_detach()
251 		drm_atomic_private_obj_fini(&bridge->base);  in drm_bridge_detach()
253 	if (bridge->funcs->detach)  in drm_bridge_detach()
254 		bridge->funcs->detach(bridge);  in drm_bridge_detach()
256 	list_del(&bridge->chain_node);  in drm_bridge_detach()
257 	bridge->dev = NULL;  in drm_bridge_detach()
261  * DOC: bridge operations
263  * Bridge drivers expose operations through the &drm_bridge_funcs structure.
265  * drm_bridge.c to call bridge operations. Those operations are divided in
266  * three big categories to support different parts of the bridge usage.
272  *   disable the bridge automatically.
279  *   Bridge drivers may implement the legacy version of those operations, or
288  *   &drm_bridge_funcs.atomic_get_input_bus_fmts allow bridge drivers to
292  *   atomic versions of those operations exist, bridge drivers that need to
300  *   puts additional burden on bridge drivers, especially for bridges that may
303  *   bridge, which doesn't always match the hardware architecture.
305  *   To simplify bridge drivers and make the connector implementation more
314  *   the bridge connector operations.
316  *   Bridge drivers shall implement the connector-related operations for all
317  *   the features that the bridge hardware support. For instance, if a bridge
320  *   bridge on a particular platform, as they could also be connected to an I2C
322  *   running platform is reported through the &drm_bridge.ops flags. Bridge
329  *   decide which bridge to delegate a connector operation to. This mechanism
331  *   bridge drivers, improving security by storing function pointers in
334  *   In order to ease transition, bridge drivers may support both the old and
336  *   connected-related bridge operations. Connector creation is then controlled
339  *   %DRM_BRIDGE_ATTACH_NO_CONNECTOR flag, and bridge drivers shall then skip
341  *   be passed to the drm_bridge_attach() call for the downstream bridge.
342  *   Bridge drivers that implement the new model only shall return an error
345  *   should use the new model, and convert the bridge drivers they use if
352  * @bridge: bridge control structure
353  * @mode: desired mode to be set for the bridge
354  * @adjusted_mode: updated mode that works for this bridge
357  * encoder chain, starting from the first bridge to the last.
359  * Note: the bridge passed should be the one closest to the encoder
364 bool drm_bridge_chain_mode_fixup(struct drm_bridge *bridge,  in drm_bridge_chain_mode_fixup()  argument
370 	if (!bridge)  in drm_bridge_chain_mode_fixup()
373 	encoder = bridge->encoder;  in drm_bridge_chain_mode_fixup()
374 	list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {  in drm_bridge_chain_mode_fixup()
375 		if (!bridge->funcs->mode_fixup)  in drm_bridge_chain_mode_fixup()
378 		if (!bridge->funcs->mode_fixup(bridge, mode, adjusted_mode))  in drm_bridge_chain_mode_fixup()
389  * @bridge: bridge control structure
394  * chain, starting from the first bridge to the last. If at least one bridge
397  * Note: the bridge passed should be the one closest to the encoder.
403 drm_bridge_chain_mode_valid(struct drm_bridge *bridge,  in drm_bridge_chain_mode_valid()  argument
409 	if (!bridge)  in drm_bridge_chain_mode_valid()
412 	encoder = bridge->encoder;  in drm_bridge_chain_mode_valid()
413 	list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {  in drm_bridge_chain_mode_valid()
416 		if (!bridge->funcs->mode_valid)  in drm_bridge_chain_mode_valid()
419 		ret = bridge->funcs->mode_valid(bridge, info, mode);  in drm_bridge_chain_mode_valid()
430  * @bridge: bridge control structure
433  * chain, starting from the last bridge to the first. These are called before
436  * Note: the bridge passed should be the one closest to the encoder
438 void drm_bridge_chain_disable(struct drm_bridge *bridge)  in drm_bridge_chain_disable()  argument
443 	if (!bridge)  in drm_bridge_chain_disable()
446 	encoder = bridge->encoder;  in drm_bridge_chain_disable()
451 		if (iter == bridge)  in drm_bridge_chain_disable()
460  * @bridge: bridge control structure
463  * encoder chain, starting from the first bridge to the last. These are called
466  * Note: the bridge passed should be the one closest to the encoder
468 void drm_bridge_chain_post_disable(struct drm_bridge *bridge)  in drm_bridge_chain_post_disable()  argument
472 	if (!bridge)  in drm_bridge_chain_post_disable()
475 	encoder = bridge->encoder;  in drm_bridge_chain_post_disable()
476 	list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {  in drm_bridge_chain_post_disable()
477 		if (bridge->funcs->post_disable)  in drm_bridge_chain_post_disable()
478 			bridge->funcs->post_disable(bridge);  in drm_bridge_chain_post_disable()
486  * @bridge: bridge control structure
491  * encoder chain, starting from the first bridge to the last.
493  * Note: the bridge passed should be the one closest to the encoder
495 void drm_bridge_chain_mode_set(struct drm_bridge *bridge,  in drm_bridge_chain_mode_set()  argument
501 	if (!bridge)  in drm_bridge_chain_mode_set()
504 	encoder = bridge->encoder;  in drm_bridge_chain_mode_set()
505 	list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {  in drm_bridge_chain_mode_set()
506 		if (bridge->funcs->mode_set)  in drm_bridge_chain_mode_set()
507 			bridge->funcs->mode_set(bridge, mode, adjusted_mode);  in drm_bridge_chain_mode_set()
515  * @bridge: bridge control structure
518  * chain, starting from the last bridge to the first. These are called
521  * Note: the bridge passed should be the one closest to the encoder
523 void drm_bridge_chain_pre_enable(struct drm_bridge *bridge)  in drm_bridge_chain_pre_enable()  argument
528 	if (!bridge)  in drm_bridge_chain_pre_enable()
531 	encoder = bridge->encoder;  in drm_bridge_chain_pre_enable()
536 		if (iter == bridge)  in drm_bridge_chain_pre_enable()
544  * @bridge: bridge control structure
547  * chain, starting from the first bridge to the last. These are called
550  * Note that the bridge passed should be the one closest to the encoder
552 void drm_bridge_chain_enable(struct drm_bridge *bridge)  in drm_bridge_chain_enable()  argument
556 	if (!bridge)  in drm_bridge_chain_enable()
559 	encoder = bridge->encoder;  in drm_bridge_chain_enable()
560 	list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {  in drm_bridge_chain_enable()
561 		if (bridge->funcs->enable)  in drm_bridge_chain_enable()
562 			bridge->funcs->enable(bridge);  in drm_bridge_chain_enable()
569  * @bridge: bridge control structure
574  * starting from the last bridge to the first. These are called before calling
577  * Note: the bridge passed should be the one closest to the encoder
579 void drm_atomic_bridge_chain_disable(struct drm_bridge *bridge,  in drm_atomic_bridge_chain_disable()  argument
585 	if (!bridge)  in drm_atomic_bridge_chain_disable()
588 	encoder = bridge->encoder;  in drm_atomic_bridge_chain_disable()
604 		if (iter == bridge)  in drm_atomic_bridge_chain_disable()
613  * @bridge: bridge control structure
618  * starting from the first bridge to the last. These are called after completing
621  * Note: the bridge passed should be the one closest to the encoder
623 void drm_atomic_bridge_chain_post_disable(struct drm_bridge *bridge,  in drm_atomic_bridge_chain_post_disable()  argument
628 	if (!bridge)  in drm_atomic_bridge_chain_post_disable()
631 	encoder = bridge->encoder;  in drm_atomic_bridge_chain_post_disable()
632 	list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {  in drm_atomic_bridge_chain_post_disable()
633 		if (bridge->funcs->atomic_post_disable) {  in drm_atomic_bridge_chain_post_disable()
638 								bridge);  in drm_atomic_bridge_chain_post_disable()
642 			bridge->funcs->atomic_post_disable(bridge,  in drm_atomic_bridge_chain_post_disable()
644 		} else if (bridge->funcs->post_disable) {  in drm_atomic_bridge_chain_post_disable()
645 			bridge->funcs->post_disable(bridge);  in drm_atomic_bridge_chain_post_disable()
654  * @bridge: bridge control structure
659  * starting from the last bridge to the first. These are called before calling
662  * Note: the bridge passed should be the one closest to the encoder
664 void drm_atomic_bridge_chain_pre_enable(struct drm_bridge *bridge,  in drm_atomic_bridge_chain_pre_enable()  argument
670 	if (!bridge)  in drm_atomic_bridge_chain_pre_enable()
673 	encoder = bridge->encoder;  in drm_atomic_bridge_chain_pre_enable()
689 		if (iter == bridge)  in drm_atomic_bridge_chain_pre_enable()
697  * @bridge: bridge control structure
702  * starting from the first bridge to the last. These are called after completing
705  * Note: the bridge passed should be the one closest to the encoder
707 void drm_atomic_bridge_chain_enable(struct drm_bridge *bridge,  in drm_atomic_bridge_chain_enable()  argument
712 	if (!bridge)  in drm_atomic_bridge_chain_enable()
715 	encoder = bridge->encoder;  in drm_atomic_bridge_chain_enable()
716 	list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {  in drm_atomic_bridge_chain_enable()
717 		if (bridge->funcs->atomic_enable) {  in drm_atomic_bridge_chain_enable()
722 								bridge);  in drm_atomic_bridge_chain_enable()
726 			bridge->funcs->atomic_enable(bridge, old_bridge_state);  in drm_atomic_bridge_chain_enable()
727 		} else if (bridge->funcs->enable) {  in drm_atomic_bridge_chain_enable()
728 			bridge->funcs->enable(bridge);  in drm_atomic_bridge_chain_enable()
734 static int drm_atomic_bridge_check(struct drm_bridge *bridge,  in drm_atomic_bridge_check()  argument
738 	if (bridge->funcs->atomic_check) {  in drm_atomic_bridge_check()
743 							       bridge);  in drm_atomic_bridge_check()
747 		ret = bridge->funcs->atomic_check(bridge, bridge_state,  in drm_atomic_bridge_check()
751 	} else if (bridge->funcs->mode_fixup) {  in drm_atomic_bridge_check()
752 		if (!bridge->funcs->mode_fixup(bridge, &crtc_state->mode,  in drm_atomic_bridge_check()
777 	 * If bus format negotiation is not supported by this bridge, let's  in select_bus_fmt_recursive()
778 	 * pass MEDIA_BUS_FMT_FIXED to the previous bridge in the chain and  in select_bus_fmt_recursive()
794 		 * fine, as long as it does not access the bridge state.  in select_bus_fmt_recursive()
849  * It performs bus format negotiation between bridge elements. The negotiation
851  * @bridge.
854  * bridge element and testing them one by one. The test is recursive, meaning
857  * transcoded to the requested output format. When a bridge element does not
859  * the next bridge element will have to try a different format. If none of the
874  * bridge element that lacks this hook and asks the previous element in the
875  * chain to try MEDIA_BUS_FMT_FIXED. It's up to bridge drivers to decide what
881 drm_atomic_bridge_chain_select_bus_fmts(struct drm_bridge *bridge,  in drm_atomic_bridge_chain_select_bus_fmts()  argument
886 	struct drm_encoder *encoder = bridge->encoder;  in drm_atomic_bridge_chain_select_bus_fmts()
931 		ret = select_bus_fmt_recursive(bridge, last_bridge, crtc_state,  in drm_atomic_bridge_chain_select_bus_fmts()
943 drm_atomic_bridge_propagate_bus_flags(struct drm_bridge *bridge,  in drm_atomic_bridge_propagate_bus_flags()  argument
951 	bridge_state = drm_atomic_get_new_bridge_state(state, bridge);  in drm_atomic_bridge_propagate_bus_flags()
953 	/* No bridge state attached to this bridge => nothing to propagate. */  in drm_atomic_bridge_propagate_bus_flags()
957 	next_bridge = drm_bridge_get_next_bridge(bridge);  in drm_atomic_bridge_propagate_bus_flags()
961 	 * display_info flags for the last bridge, and propagate the input  in drm_atomic_bridge_propagate_bus_flags()
962 	 * flags of the next bridge element to the output end of the current  in drm_atomic_bridge_propagate_bus_flags()
963 	 * bridge when the bridge is not the last one.  in drm_atomic_bridge_propagate_bus_flags()
975 		 * No bridge state attached to the next bridge, just leave the  in drm_atomic_bridge_propagate_bus_flags()
985 	 * Propagate the output flags to the input end of the bridge. Again, it's  in drm_atomic_bridge_propagate_bus_flags()
994  * drm_atomic_bridge_chain_check() - Do an atomic check on the bridge chain
995  * @bridge: bridge control structure
1002  * starting from the last bridge to the first. These are called before calling
1008 int drm_atomic_bridge_chain_check(struct drm_bridge *bridge,  in drm_atomic_bridge_chain_check()  argument
1017 	if (!bridge)  in drm_atomic_bridge_chain_check()
1020 	ret = drm_atomic_bridge_chain_select_bus_fmts(bridge, crtc_state,  in drm_atomic_bridge_chain_check()
1025 	encoder = bridge->encoder;  in drm_atomic_bridge_chain_check()
1030 		 * Bus flags are propagated by default. If a bridge needs to  in drm_atomic_bridge_chain_check()
1043 		if (iter == bridge)  in drm_atomic_bridge_chain_check()
1052  * drm_bridge_detect - check if anything is attached to the bridge output
1053  * @bridge: bridge control structure
1055  * If the bridge supports output detection, as reported by the
1056  * DRM_BRIDGE_OP_DETECT bridge ops flag, call &drm_bridge_funcs.detect for the
1057  * bridge and return the connection status. Otherwise return
1061  * The detection status on success, or connector_status_unknown if the bridge
1064 enum drm_connector_status drm_bridge_detect(struct drm_bridge *bridge)  in drm_bridge_detect()  argument
1066 	if (!(bridge->ops & DRM_BRIDGE_OP_DETECT))  in drm_bridge_detect()
1069 	return bridge->funcs->detect(bridge);  in drm_bridge_detect()
1076  * @bridge: bridge control structure
1079  * If the bridge supports output modes retrieval, as reported by the
1080  * DRM_BRIDGE_OP_MODES bridge ops flag, call &drm_bridge_funcs.get_modes to
1087 int drm_bridge_get_modes(struct drm_bridge *bridge,  in drm_bridge_get_modes()  argument
1090 	if (!(bridge->ops & DRM_BRIDGE_OP_MODES))  in drm_bridge_get_modes()
1093 	return bridge->funcs->get_modes(bridge, connector);  in drm_bridge_get_modes()
1099  * @bridge: bridge control structure
1102  * If the bridge supports output EDID retrieval, as reported by the
1103  * DRM_BRIDGE_OP_EDID bridge ops flag, call &drm_bridge_funcs.get_edid to
1109 struct edid *drm_bridge_get_edid(struct drm_bridge *bridge,  in drm_bridge_get_edid()  argument
1112 	if (!(bridge->ops & DRM_BRIDGE_OP_EDID))  in drm_bridge_get_edid()
1115 	return bridge->funcs->get_edid(bridge, connector);  in drm_bridge_get_edid()
1120  * drm_bridge_hpd_enable - enable hot plug detection for the bridge
1121  * @bridge: bridge control structure
1127  * called with @data when an output status change is detected by the bridge,
1131  * bridge->ops. This function shall not be called when the flag is not set.
1135  * the bridge.
1137 void drm_bridge_hpd_enable(struct drm_bridge *bridge,  in drm_bridge_hpd_enable()  argument
1142 	if (!(bridge->ops & DRM_BRIDGE_OP_HPD))  in drm_bridge_hpd_enable()
1145 	mutex_lock(&bridge->hpd_mutex);  in drm_bridge_hpd_enable()
1147 	if (WARN(bridge->hpd_cb, "Hot plug detection already enabled\n"))  in drm_bridge_hpd_enable()
1150 	bridge->hpd_cb = cb;  in drm_bridge_hpd_enable()
1151 	bridge->hpd_data = data;  in drm_bridge_hpd_enable()
1153 	if (bridge->funcs->hpd_enable)  in drm_bridge_hpd_enable()
1154 		bridge->funcs->hpd_enable(bridge);  in drm_bridge_hpd_enable()
1157 	mutex_unlock(&bridge->hpd_mutex);  in drm_bridge_hpd_enable()
1162  * drm_bridge_hpd_disable - disable hot plug detection for the bridge
1163  * @bridge: bridge control structure
1167  * Once this function returns the callback will not be called by the bridge
1171  * bridge->ops. This function shall not be called when the flag is not set.
1173 void drm_bridge_hpd_disable(struct drm_bridge *bridge)  in drm_bridge_hpd_disable()  argument
1175 	if (!(bridge->ops & DRM_BRIDGE_OP_HPD))  in drm_bridge_hpd_disable()
1178 	mutex_lock(&bridge->hpd_mutex);  in drm_bridge_hpd_disable()
1179 	if (bridge->funcs->hpd_disable)  in drm_bridge_hpd_disable()
1180 		bridge->funcs->hpd_disable(bridge);  in drm_bridge_hpd_disable()
1182 	bridge->hpd_cb = NULL;  in drm_bridge_hpd_disable()
1183 	bridge->hpd_data = NULL;  in drm_bridge_hpd_disable()
1184 	mutex_unlock(&bridge->hpd_mutex);  in drm_bridge_hpd_disable()
1190  * @bridge: bridge control structure
1193  * Bridge drivers shall call this function to report hot plug events when they
1199 void drm_bridge_hpd_notify(struct drm_bridge *bridge,  in drm_bridge_hpd_notify()  argument
1202 	mutex_lock(&bridge->hpd_mutex);  in drm_bridge_hpd_notify()
1203 	if (bridge->hpd_cb)  in drm_bridge_hpd_notify()
1204 		bridge->hpd_cb(bridge->hpd_data, status);  in drm_bridge_hpd_notify()
1205 	mutex_unlock(&bridge->hpd_mutex);  in drm_bridge_hpd_notify()
1211  * of_drm_find_bridge - find the bridge corresponding to the device node in
1212  *			the global bridge list
1221 	struct drm_bridge *bridge;  in of_drm_find_bridge()  local
1225 	list_for_each_entry(bridge, &bridge_list, list) {  in of_drm_find_bridge()
1226 		if (bridge->of_node == np) {  in of_drm_find_bridge()
1228 			return bridge;  in of_drm_find_bridge()
1239 MODULE_DESCRIPTION("DRM bridge infrastructure");