44  * A bridge is always attached to a single &drm_encoder at a time, but can be
47  *     [ CRTC ---> ] Encoder ---> Bridge A ---> Bridge B
49  * Here, the output of the encoder feeds to bridge A, and that furthers feeds to
50  * bridge B. Bridge chains can be arbitrarily long, and shall be fully linear:
51  * Chaining multiple bridges to the output of a bridge, or the same bridge to
63  * Display drivers are responsible for linking encoders with the first bridge
64  * in the chains. This is done by acquiring the appropriate bridge with
65  * devm_drm_of_get_bridge(). Once acquired, the bridge shall be attached to the
68  * Bridges are responsible for linking themselves with the next bridge in the
90  * DRM bridge chain functions shall be called manually.
93  * the bridge chain. Display drivers may use the drm_bridge_connector_init()
95  * connector-related operations exposed by the bridge (see the overview
96  * documentation of bridge operations for more details).
103  * the probing of the upstream driver and the bridge driver can be
108  *   MIPI-DSI host. In this case, the bridge driver will probe at some
110  *   EPROBE_DEFER as long as the bridge driver hasn't probed.
113  *   MIPI-DSI host. The bridge device uses the MIPI-DCS commands to be
114  *   controlled. In this case, the bridge device is a child of the
117  *   assured that the bridge driver is connected between the
124  *   host. The bridge device uses the MIPI-DCS commands to be
129  *   host. The bridge device uses a separate bus (such as I2C) to be
131  *   of the bridge and upstream drivers, so care must be taken to avoid
142  * - In its probe hook, the bridge driver must try to find its MIPI-DSI
144  *   to its host. The bridge driver is now functional.
148  *   the bridge driver is attached and registered, we can now look for
152  * the bridge driver are functional and we can't have a deadlock-like
160  * drm_bridge_add - add the given bridge to the global bridge list
162  * @bridge: bridge control structure
164 void drm_bridge_add(struct drm_bridge *bridge)  in drm_bridge_add()  argument
166 	mutex_init(&bridge->hpd_mutex);  in drm_bridge_add()
169 	list_add_tail(&bridge->list, &bridge_list);  in drm_bridge_add()
174 static void drm_bridge_remove_void(void *bridge)  in drm_bridge_remove_void()  argument
176 	drm_bridge_remove(bridge);  in drm_bridge_remove_void()
182  * @dev: device to tie the bridge lifetime to
183  * @bridge: bridge control structure
190 int devm_drm_bridge_add(struct device *dev, struct drm_bridge *bridge)  in devm_drm_bridge_add()  argument
192 	drm_bridge_add(bridge);  in devm_drm_bridge_add()
193 	return devm_add_action_or_reset(dev, drm_bridge_remove_void, bridge);  in devm_drm_bridge_add()
198  * drm_bridge_remove - remove the given bridge from the global bridge list
200  * @bridge: bridge control structure
202 void drm_bridge_remove(struct drm_bridge *bridge)  in drm_bridge_remove()  argument
205 	list_del_init(&bridge->list);  in drm_bridge_remove()
208 	mutex_destroy(&bridge->hpd_mutex);  in drm_bridge_remove()
215 	struct drm_bridge *bridge = drm_priv_to_bridge(obj);  in drm_bridge_atomic_duplicate_priv_state()  local
218 	state = bridge->funcs->atomic_duplicate_state(bridge);  in drm_bridge_atomic_duplicate_priv_state()
227 	struct drm_bridge *bridge = drm_priv_to_bridge(obj);  in drm_bridge_atomic_destroy_priv_state()  local
229 	bridge->funcs->atomic_destroy_state(bridge, state);  in drm_bridge_atomic_destroy_priv_state()
238  * drm_bridge_attach - attach the bridge to an encoder's chain
241  * @bridge: bridge to attach
242  * @previous: previous bridge in the chain (optional)
245  * Called by a kms driver to link the bridge to an encoder's chain. The previous
246  * argument specifies the previous bridge in the chain. If NULL, the bridge is
248  * previous bridge's output.
250  * If non-NULL the previous bridge must be already attached by a call to this
260 int drm_bridge_attach(struct drm_encoder *encoder, struct drm_bridge *bridge,  in drm_bridge_attach()  argument
266 	if (!encoder || !bridge)  in drm_bridge_attach()
272 	if (bridge->dev)  in drm_bridge_attach()
275 	bridge->dev = encoder->dev;  in drm_bridge_attach()
276 	bridge->encoder = encoder;  in drm_bridge_attach()
279 		list_add(&bridge->chain_node, &previous->chain_node);  in drm_bridge_attach()
281 		list_add(&bridge->chain_node, &encoder->bridge_chain);  in drm_bridge_attach()
283 	if (bridge->funcs->attach) {  in drm_bridge_attach()
284 		ret = bridge->funcs->attach(bridge, flags);  in drm_bridge_attach()
289 	if (bridge->funcs->atomic_reset) {  in drm_bridge_attach()
292 		state = bridge->funcs->atomic_reset(bridge);  in drm_bridge_attach()
298 		drm_atomic_private_obj_init(bridge->dev, &bridge->base,  in drm_bridge_attach()
306 	if (bridge->funcs->detach)  in drm_bridge_attach()
307 		bridge->funcs->detach(bridge);  in drm_bridge_attach()
310 	bridge->dev = NULL;  in drm_bridge_attach()
311 	bridge->encoder = NULL;  in drm_bridge_attach()
312 	list_del(&bridge->chain_node);  in drm_bridge_attach()
315 	DRM_ERROR("failed to attach bridge %pOF to encoder %s: %d\n",  in drm_bridge_attach()
316 		  bridge->of_node, encoder->name, ret);  in drm_bridge_attach()
318 	DRM_ERROR("failed to attach bridge to encoder %s: %d\n",  in drm_bridge_attach()
326 void drm_bridge_detach(struct drm_bridge *bridge)  in drm_bridge_detach()  argument
328 	if (WARN_ON(!bridge))  in drm_bridge_detach()
331 	if (WARN_ON(!bridge->dev))  in drm_bridge_detach()
334 	if (bridge->funcs->atomic_reset)  in drm_bridge_detach()
335 		drm_atomic_private_obj_fini(&bridge->base);  in drm_bridge_detach()
337 	if (bridge->funcs->detach)  in drm_bridge_detach()
338 		bridge->funcs->detach(bridge);  in drm_bridge_detach()
340 	list_del(&bridge->chain_node);  in drm_bridge_detach()
341 	bridge->dev = NULL;  in drm_bridge_detach()
345  * DOC: bridge operations
347  * Bridge drivers expose operations through the &drm_bridge_funcs structure.
349  * drm_bridge.c to call bridge operations. Those operations are divided in
350  * three big categories to support different parts of the bridge usage.
356  *   disable the bridge automatically.
363  *   Bridge drivers may implement the legacy version of those operations, or
372  *   &drm_bridge_funcs.atomic_get_input_bus_fmts allow bridge drivers to
376  *   atomic versions of those operations exist, bridge drivers that need to
384  *   puts additional burden on bridge drivers, especially for bridges that may
387  *   bridge, which doesn't always match the hardware architecture.
389  *   To simplify bridge drivers and make the connector implementation more
398  *   the bridge connector operations.
400  *   Bridge drivers shall implement the connector-related operations for all
401  *   the features that the bridge hardware support. For instance, if a bridge
404  *   bridge on a particular platform, as they could also be connected to an I2C
406  *   running platform is reported through the &drm_bridge.ops flags. Bridge
413  *   decide which bridge to delegate a connector operation to. This mechanism
415  *   bridge drivers, improving security by storing function pointers in
418  *   In order to ease transition, bridge drivers may support both the old and
420  *   connected-related bridge operations. Connector creation is then controlled
423  *   %DRM_BRIDGE_ATTACH_NO_CONNECTOR flag, and bridge drivers shall then skip
425  *   be passed to the drm_bridge_attach() call for the downstream bridge.
426  *   Bridge drivers that implement the new model only shall return an error
429  *   should use the new model, and convert the bridge drivers they use if
436  * @bridge: bridge control structure
437  * @mode: desired mode to be set for the bridge
438  * @adjusted_mode: updated mode that works for this bridge
441  * encoder chain, starting from the first bridge to the last.
443  * Note: the bridge passed should be the one closest to the encoder
448 bool drm_bridge_chain_mode_fixup(struct drm_bridge *bridge,  in drm_bridge_chain_mode_fixup()  argument
454 	if (!bridge)  in drm_bridge_chain_mode_fixup()
457 	encoder = bridge->encoder;  in drm_bridge_chain_mode_fixup()
458 	list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {  in drm_bridge_chain_mode_fixup()
459 		if (!bridge->funcs->mode_fixup)  in drm_bridge_chain_mode_fixup()
462 		if (!bridge->funcs->mode_fixup(bridge, mode, adjusted_mode))  in drm_bridge_chain_mode_fixup()
473  * @bridge: bridge control structure
478  * chain, starting from the first bridge to the last. If at least one bridge
481  * Note: the bridge passed should be the one closest to the encoder.
487 drm_bridge_chain_mode_valid(struct drm_bridge *bridge,  in drm_bridge_chain_mode_valid()  argument
493 	if (!bridge)  in drm_bridge_chain_mode_valid()
496 	encoder = bridge->encoder;  in drm_bridge_chain_mode_valid()
497 	list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {  in drm_bridge_chain_mode_valid()
500 		if (!bridge->funcs->mode_valid)  in drm_bridge_chain_mode_valid()
503 		ret = bridge->funcs->mode_valid(bridge, info, mode);  in drm_bridge_chain_mode_valid()
514  * @bridge: bridge control structure
517  * chain, starting from the last bridge to the first. These are called before
520  * Note: the bridge passed should be the one closest to the encoder
522 void drm_bridge_chain_disable(struct drm_bridge *bridge)  in drm_bridge_chain_disable()  argument
527 	if (!bridge)  in drm_bridge_chain_disable()
530 	encoder = bridge->encoder;  in drm_bridge_chain_disable()
535 		if (iter == bridge)  in drm_bridge_chain_disable()
544  * @bridge: bridge control structure
547  * encoder chain, starting from the first bridge to the last. These are called
550  * Note: the bridge passed should be the one closest to the encoder
552 void drm_bridge_chain_post_disable(struct drm_bridge *bridge)  in drm_bridge_chain_post_disable()  argument
556 	if (!bridge)  in drm_bridge_chain_post_disable()
559 	encoder = bridge->encoder;  in drm_bridge_chain_post_disable()
560 	list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {  in drm_bridge_chain_post_disable()
561 		if (bridge->funcs->post_disable)  in drm_bridge_chain_post_disable()
562 			bridge->funcs->post_disable(bridge);  in drm_bridge_chain_post_disable()
570  * @bridge: bridge control structure
575  * encoder chain, starting from the first bridge to the last.
577  * Note: the bridge passed should be the one closest to the encoder
579 void drm_bridge_chain_mode_set(struct drm_bridge *bridge,  in drm_bridge_chain_mode_set()  argument
585 	if (!bridge)  in drm_bridge_chain_mode_set()
588 	encoder = bridge->encoder;  in drm_bridge_chain_mode_set()
589 	list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {  in drm_bridge_chain_mode_set()
590 		if (bridge->funcs->mode_set)  in drm_bridge_chain_mode_set()
591 			bridge->funcs->mode_set(bridge, mode, adjusted_mode);  in drm_bridge_chain_mode_set()
599  * @bridge: bridge control structure
602  * chain, starting from the last bridge to the first. These are called
605  * Note: the bridge passed should be the one closest to the encoder
607 void drm_bridge_chain_pre_enable(struct drm_bridge *bridge)  in drm_bridge_chain_pre_enable()  argument
612 	if (!bridge)  in drm_bridge_chain_pre_enable()
615 	encoder = bridge->encoder;  in drm_bridge_chain_pre_enable()
620 		if (iter == bridge)  in drm_bridge_chain_pre_enable()
628  * @bridge: bridge control structure
631  * chain, starting from the first bridge to the last. These are called
634  * Note that the bridge passed should be the one closest to the encoder
636 void drm_bridge_chain_enable(struct drm_bridge *bridge)  in drm_bridge_chain_enable()  argument
640 	if (!bridge)  in drm_bridge_chain_enable()
643 	encoder = bridge->encoder;  in drm_bridge_chain_enable()
644 	list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {  in drm_bridge_chain_enable()
645 		if (bridge->funcs->enable)  in drm_bridge_chain_enable()
646 			bridge->funcs->enable(bridge);  in drm_bridge_chain_enable()
653  * @bridge: bridge control structure
658  * starting from the last bridge to the first. These are called before calling
661  * Note: the bridge passed should be the one closest to the encoder
663 void drm_atomic_bridge_chain_disable(struct drm_bridge *bridge,  in drm_atomic_bridge_chain_disable()  argument
669 	if (!bridge)  in drm_atomic_bridge_chain_disable()
672 	encoder = bridge->encoder;  in drm_atomic_bridge_chain_disable()
688 		if (iter == bridge)  in drm_atomic_bridge_chain_disable()
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_post_disable(struct drm_bridge *bridge,  in drm_atomic_bridge_chain_post_disable()  argument
712 	if (!bridge)  in drm_atomic_bridge_chain_post_disable()
715 	encoder = bridge->encoder;  in drm_atomic_bridge_chain_post_disable()
716 	list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {  in drm_atomic_bridge_chain_post_disable()
717 		if (bridge->funcs->atomic_post_disable) {  in drm_atomic_bridge_chain_post_disable()
722 								bridge);  in drm_atomic_bridge_chain_post_disable()
726 			bridge->funcs->atomic_post_disable(bridge,  in drm_atomic_bridge_chain_post_disable()
728 		} else if (bridge->funcs->post_disable) {  in drm_atomic_bridge_chain_post_disable()
729 			bridge->funcs->post_disable(bridge);  in drm_atomic_bridge_chain_post_disable()
738  * @bridge: bridge control structure
743  * starting from the last bridge to the first. These are called before calling
746  * Note: the bridge passed should be the one closest to the encoder
748 void drm_atomic_bridge_chain_pre_enable(struct drm_bridge *bridge,  in drm_atomic_bridge_chain_pre_enable()  argument
754 	if (!bridge)  in drm_atomic_bridge_chain_pre_enable()
757 	encoder = bridge->encoder;  in drm_atomic_bridge_chain_pre_enable()
773 		if (iter == bridge)  in drm_atomic_bridge_chain_pre_enable()
781  * @bridge: bridge control structure
786  * starting from the first bridge to the last. These are called after completing
789  * Note: the bridge passed should be the one closest to the encoder
791 void drm_atomic_bridge_chain_enable(struct drm_bridge *bridge,  in drm_atomic_bridge_chain_enable()  argument
796 	if (!bridge)  in drm_atomic_bridge_chain_enable()
799 	encoder = bridge->encoder;  in drm_atomic_bridge_chain_enable()
800 	list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {  in drm_atomic_bridge_chain_enable()
801 		if (bridge->funcs->atomic_enable) {  in drm_atomic_bridge_chain_enable()
806 								bridge);  in drm_atomic_bridge_chain_enable()
810 			bridge->funcs->atomic_enable(bridge, old_bridge_state);  in drm_atomic_bridge_chain_enable()
811 		} else if (bridge->funcs->enable) {  in drm_atomic_bridge_chain_enable()
812 			bridge->funcs->enable(bridge);  in drm_atomic_bridge_chain_enable()
818 static int drm_atomic_bridge_check(struct drm_bridge *bridge,  in drm_atomic_bridge_check()  argument
822 	if (bridge->funcs->atomic_check) {  in drm_atomic_bridge_check()
827 							       bridge);  in drm_atomic_bridge_check()
831 		ret = bridge->funcs->atomic_check(bridge, bridge_state,  in drm_atomic_bridge_check()
835 	} else if (bridge->funcs->mode_fixup) {  in drm_atomic_bridge_check()
836 		if (!bridge->funcs->mode_fixup(bridge, &crtc_state->mode,  in drm_atomic_bridge_check()
861 	 * If bus format negotiation is not supported by this bridge, let's  in select_bus_fmt_recursive()
862 	 * pass MEDIA_BUS_FMT_FIXED to the previous bridge in the chain and  in select_bus_fmt_recursive()
878 		 * fine, as long as it does not access the bridge state.  in select_bus_fmt_recursive()
933  * It performs bus format negotiation between bridge elements. The negotiation
935  * @bridge.
938  * bridge element and testing them one by one. The test is recursive, meaning
941  * transcoded to the requested output format. When a bridge element does not
943  * the next bridge element will have to try a different format. If none of the
958  * bridge element that lacks this hook and asks the previous element in the
959  * chain to try MEDIA_BUS_FMT_FIXED. It's up to bridge drivers to decide what
965 drm_atomic_bridge_chain_select_bus_fmts(struct drm_bridge *bridge,  in drm_atomic_bridge_chain_select_bus_fmts()  argument
970 	struct drm_encoder *encoder = bridge->encoder;  in drm_atomic_bridge_chain_select_bus_fmts()
1015 		ret = select_bus_fmt_recursive(bridge, last_bridge, crtc_state,  in drm_atomic_bridge_chain_select_bus_fmts()
1027 drm_atomic_bridge_propagate_bus_flags(struct drm_bridge *bridge,  in drm_atomic_bridge_propagate_bus_flags()  argument
1035 	bridge_state = drm_atomic_get_new_bridge_state(state, bridge);  in drm_atomic_bridge_propagate_bus_flags()
1037 	/* No bridge state attached to this bridge => nothing to propagate. */  in drm_atomic_bridge_propagate_bus_flags()
1041 	next_bridge = drm_bridge_get_next_bridge(bridge);  in drm_atomic_bridge_propagate_bus_flags()
1045 	 * display_info flags for the last bridge, and propagate the input  in drm_atomic_bridge_propagate_bus_flags()
1046 	 * flags of the next bridge element to the output end of the current  in drm_atomic_bridge_propagate_bus_flags()
1047 	 * bridge when the bridge is not the last one.  in drm_atomic_bridge_propagate_bus_flags()
1059 		 * No bridge state attached to the next bridge, just leave the  in drm_atomic_bridge_propagate_bus_flags()
1069 	 * Propagate the output flags to the input end of the bridge. Again, it's  in drm_atomic_bridge_propagate_bus_flags()
1078  * drm_atomic_bridge_chain_check() - Do an atomic check on the bridge chain
1079  * @bridge: bridge control structure
1086  * starting from the last bridge to the first. These are called before calling
1092 int drm_atomic_bridge_chain_check(struct drm_bridge *bridge,  in drm_atomic_bridge_chain_check()  argument
1101 	if (!bridge)  in drm_atomic_bridge_chain_check()
1104 	ret = drm_atomic_bridge_chain_select_bus_fmts(bridge, crtc_state,  in drm_atomic_bridge_chain_check()
1109 	encoder = bridge->encoder;  in drm_atomic_bridge_chain_check()
1114 		 * Bus flags are propagated by default. If a bridge needs to  in drm_atomic_bridge_chain_check()
1127 		if (iter == bridge)  in drm_atomic_bridge_chain_check()
1136  * drm_bridge_detect - check if anything is attached to the bridge output
1137  * @bridge: bridge control structure
1139  * If the bridge supports output detection, as reported by the
1140  * DRM_BRIDGE_OP_DETECT bridge ops flag, call &drm_bridge_funcs.detect for the
1141  * bridge and return the connection status. Otherwise return
1145  * The detection status on success, or connector_status_unknown if the bridge
1148 enum drm_connector_status drm_bridge_detect(struct drm_bridge *bridge)  in drm_bridge_detect()  argument
1150 	if (!(bridge->ops & DRM_BRIDGE_OP_DETECT))  in drm_bridge_detect()
1153 	return bridge->funcs->detect(bridge);  in drm_bridge_detect()
1160  * @bridge: bridge control structure
1163  * If the bridge supports output modes retrieval, as reported by the
1164  * DRM_BRIDGE_OP_MODES bridge ops flag, call &drm_bridge_funcs.get_modes to
1171 int drm_bridge_get_modes(struct drm_bridge *bridge,  in drm_bridge_get_modes()  argument
1174 	if (!(bridge->ops & DRM_BRIDGE_OP_MODES))  in drm_bridge_get_modes()
1177 	return bridge->funcs->get_modes(bridge, connector);  in drm_bridge_get_modes()
1183  * @bridge: bridge control structure
1186  * If the bridge supports output EDID retrieval, as reported by the
1187  * DRM_BRIDGE_OP_EDID bridge ops flag, call &drm_bridge_funcs.get_edid to
1193 struct edid *drm_bridge_get_edid(struct drm_bridge *bridge,  in drm_bridge_get_edid()  argument
1196 	if (!(bridge->ops & DRM_BRIDGE_OP_EDID))  in drm_bridge_get_edid()
1199 	return bridge->funcs->get_edid(bridge, connector);  in drm_bridge_get_edid()
1204  * drm_bridge_hpd_enable - enable hot plug detection for the bridge
1205  * @bridge: bridge control structure
1211  * called with @data when an output status change is detected by the bridge,
1215  * bridge->ops. This function shall not be called when the flag is not set.
1219  * the bridge.
1221 void drm_bridge_hpd_enable(struct drm_bridge *bridge,  in drm_bridge_hpd_enable()  argument
1226 	if (!(bridge->ops & DRM_BRIDGE_OP_HPD))  in drm_bridge_hpd_enable()
1229 	mutex_lock(&bridge->hpd_mutex);  in drm_bridge_hpd_enable()
1231 	if (WARN(bridge->hpd_cb, "Hot plug detection already enabled\n"))  in drm_bridge_hpd_enable()
1234 	bridge->hpd_cb = cb;  in drm_bridge_hpd_enable()
1235 	bridge->hpd_data = data;  in drm_bridge_hpd_enable()
1237 	if (bridge->funcs->hpd_enable)  in drm_bridge_hpd_enable()
1238 		bridge->funcs->hpd_enable(bridge);  in drm_bridge_hpd_enable()
1241 	mutex_unlock(&bridge->hpd_mutex);  in drm_bridge_hpd_enable()
1246  * drm_bridge_hpd_disable - disable hot plug detection for the bridge
1247  * @bridge: bridge control structure
1251  * Once this function returns the callback will not be called by the bridge
1255  * bridge->ops. This function shall not be called when the flag is not set.
1257 void drm_bridge_hpd_disable(struct drm_bridge *bridge)  in drm_bridge_hpd_disable()  argument
1259 	if (!(bridge->ops & DRM_BRIDGE_OP_HPD))  in drm_bridge_hpd_disable()
1262 	mutex_lock(&bridge->hpd_mutex);  in drm_bridge_hpd_disable()
1263 	if (bridge->funcs->hpd_disable)  in drm_bridge_hpd_disable()
1264 		bridge->funcs->hpd_disable(bridge);  in drm_bridge_hpd_disable()
1266 	bridge->hpd_cb = NULL;  in drm_bridge_hpd_disable()
1267 	bridge->hpd_data = NULL;  in drm_bridge_hpd_disable()
1268 	mutex_unlock(&bridge->hpd_mutex);  in drm_bridge_hpd_disable()
1274  * @bridge: bridge control structure
1277  * Bridge drivers shall call this function to report hot plug events when they
1283 void drm_bridge_hpd_notify(struct drm_bridge *bridge,  in drm_bridge_hpd_notify()  argument
1286 	mutex_lock(&bridge->hpd_mutex);  in drm_bridge_hpd_notify()
1287 	if (bridge->hpd_cb)  in drm_bridge_hpd_notify()
1288 		bridge->hpd_cb(bridge->hpd_data, status);  in drm_bridge_hpd_notify()
1289 	mutex_unlock(&bridge->hpd_mutex);  in drm_bridge_hpd_notify()
1295  * of_drm_find_bridge - find the bridge corresponding to the device node in
1296  *			the global bridge list
1305 	struct drm_bridge *bridge;  in of_drm_find_bridge()  local
1309 	list_for_each_entry(bridge, &bridge_list, list) {  in of_drm_find_bridge()
1310 		if (bridge->of_node == np) {  in of_drm_find_bridge()
1312 			return bridge;  in of_drm_find_bridge()
1323 MODULE_DESCRIPTION("DRM bridge infrastructure");