47  * A bridge is always attached to a single &drm_encoder at a time, but can be
50  *     [ CRTC ---> ] Encoder ---> Bridge A ---> Bridge B
52  * Here, the output of the encoder feeds to bridge A, and that furthers feeds to
53  * bridge B. Bridge chains can be arbitrarily long, and shall be fully linear:
54  * Chaining multiple bridges to the output of a bridge, or the same bridge to
66  * Display drivers are responsible for linking encoders with the first bridge
67  * in the chains. This is done by acquiring the appropriate bridge with
68  * devm_drm_of_get_bridge(). Once acquired, the bridge shall be attached to the
71  * Bridges are responsible for linking themselves with the next bridge in the
93  * DRM bridge chain functions shall be called manually.
96  * the bridge chain. Display drivers may use the drm_bridge_connector_init()
98  * connector-related operations exposed by the bridge (see the overview
99  * documentation of bridge operations for more details).
106  * the probing of the upstream driver and the bridge driver can be
111  *   MIPI-DSI host. In this case, the bridge driver will probe at some
113  *   EPROBE_DEFER as long as the bridge driver hasn't probed.
116  *   MIPI-DSI host. The bridge device uses the MIPI-DCS commands to be
117  *   controlled. In this case, the bridge device is a child of the
120  *   assured that the bridge driver is connected between the
127  *   host. The bridge device uses the MIPI-DCS commands to be
132  *   host. The bridge device uses a separate bus (such as I2C) to be
134  *   of the bridge and upstream drivers, so care must be taken to avoid
145  * - In its probe hook, the bridge driver must try to find its MIPI-DSI
147  *   to its host. The bridge driver is now functional.
151  *   the bridge driver is attached and registered, we can now look for
155  * the bridge driver are functional and we can't have a deadlock-like
160  * DOC: dsi bridge operations
173  * Ordinarily the downstream bridge DSI peripheral pre_enable will have been
186  * bridge &post_disable will be called before the DSI host's post_disable.
202  * drm_bridge_add - add the given bridge to the global bridge list
204  * @bridge: bridge control structure
206 void drm_bridge_add(struct drm_bridge *bridge)  in drm_bridge_add()  argument
208 	mutex_init(&bridge->hpd_mutex);  in drm_bridge_add()
210 	if (bridge->ops & DRM_BRIDGE_OP_HDMI)  in drm_bridge_add()
211 		bridge->ycbcr_420_allowed = !!(bridge->supported_formats &  in drm_bridge_add()
215 	list_add_tail(&bridge->list, &bridge_list);  in drm_bridge_add()
220 static void drm_bridge_remove_void(void *bridge)  in drm_bridge_remove_void()  argument
222 	drm_bridge_remove(bridge);  in drm_bridge_remove_void()
228  * @dev: device to tie the bridge lifetime to
229  * @bridge: bridge control structure
236 int devm_drm_bridge_add(struct device *dev, struct drm_bridge *bridge)  in devm_drm_bridge_add()  argument
238 	drm_bridge_add(bridge);  in devm_drm_bridge_add()
239 	return devm_add_action_or_reset(dev, drm_bridge_remove_void, bridge);  in devm_drm_bridge_add()
244  * drm_bridge_remove - remove the given bridge from the global bridge list
246  * @bridge: bridge control structure
248 void drm_bridge_remove(struct drm_bridge *bridge)  in drm_bridge_remove()  argument
251 	list_del_init(&bridge->list);  in drm_bridge_remove()
254 	mutex_destroy(&bridge->hpd_mutex);  in drm_bridge_remove()
261 	struct drm_bridge *bridge = drm_priv_to_bridge(obj);  in drm_bridge_atomic_duplicate_priv_state()  local
264 	state = bridge->funcs->atomic_duplicate_state(bridge);  in drm_bridge_atomic_duplicate_priv_state()
273 	struct drm_bridge *bridge = drm_priv_to_bridge(obj);  in drm_bridge_atomic_destroy_priv_state()  local
275 	bridge->funcs->atomic_destroy_state(bridge, state);  in drm_bridge_atomic_destroy_priv_state()
284  * drm_bridge_attach - attach the bridge to an encoder's chain
287  * @bridge: bridge to attach
288  * @previous: previous bridge in the chain (optional)
291  * Called by a kms driver to link the bridge to an encoder's chain. The previous
292  * argument specifies the previous bridge in the chain. If NULL, the bridge is
294  * previous bridge's output.
296  * If non-NULL the previous bridge must be already attached by a call to this
306 int drm_bridge_attach(struct drm_encoder *encoder, struct drm_bridge *bridge,  in drm_bridge_attach()  argument
312 	if (!encoder || !bridge)  in drm_bridge_attach()
318 	if (bridge->dev)  in drm_bridge_attach()
321 	bridge->dev = encoder->dev;  in drm_bridge_attach()
322 	bridge->encoder = encoder;  in drm_bridge_attach()
325 		list_add(&bridge->chain_node, &previous->chain_node);  in drm_bridge_attach()
327 		list_add(&bridge->chain_node, &encoder->bridge_chain);  in drm_bridge_attach()
329 	if (bridge->funcs->attach) {  in drm_bridge_attach()
330 		ret = bridge->funcs->attach(bridge, flags);  in drm_bridge_attach()
335 	if (bridge->funcs->atomic_reset) {  in drm_bridge_attach()
338 		state = bridge->funcs->atomic_reset(bridge);  in drm_bridge_attach()
344 		drm_atomic_private_obj_init(bridge->dev, &bridge->base,  in drm_bridge_attach()
352 	if (bridge->funcs->detach)  in drm_bridge_attach()
353 		bridge->funcs->detach(bridge);  in drm_bridge_attach()
356 	bridge->dev = NULL;  in drm_bridge_attach()
357 	bridge->encoder = NULL;  in drm_bridge_attach()
358 	list_del(&bridge->chain_node);  in drm_bridge_attach()
361 		DRM_ERROR("failed to attach bridge %pOF to encoder %s: %d\n",  in drm_bridge_attach()
362 			  bridge->of_node, encoder->name, ret);  in drm_bridge_attach()
365 			      "failed to attach bridge %pOF to encoder %s\n",  in drm_bridge_attach()
366 			      bridge->of_node, encoder->name);  in drm_bridge_attach()
372 void drm_bridge_detach(struct drm_bridge *bridge)  in drm_bridge_detach()  argument
374 	if (WARN_ON(!bridge))  in drm_bridge_detach()
377 	if (WARN_ON(!bridge->dev))  in drm_bridge_detach()
380 	if (bridge->funcs->atomic_reset)  in drm_bridge_detach()
381 		drm_atomic_private_obj_fini(&bridge->base);  in drm_bridge_detach()
383 	if (bridge->funcs->detach)  in drm_bridge_detach()
384 		bridge->funcs->detach(bridge);  in drm_bridge_detach()
386 	list_del(&bridge->chain_node);  in drm_bridge_detach()
387 	bridge->dev = NULL;  in drm_bridge_detach()
391  * DOC: bridge operations
393  * Bridge drivers expose operations through the &drm_bridge_funcs structure.
395  * drm_bridge.c to call bridge operations. Those operations are divided in
396  * three big categories to support different parts of the bridge usage.
402  *   disable the bridge automatically.
409  *   Bridge drivers may implement the legacy version of those operations, or
418  *   &drm_bridge_funcs.atomic_get_input_bus_fmts allow bridge drivers to
422  *   atomic versions of those operations exist, bridge drivers that need to
430  *   puts additional burden on bridge drivers, especially for bridges that may
433  *   bridge, which doesn't always match the hardware architecture.
435  *   To simplify bridge drivers and make the connector implementation more
444  *   the bridge connector operations.
446  *   Bridge drivers shall implement the connector-related operations for all
447  *   the features that the bridge hardware support. For instance, if a bridge
450  *   bridge on a particular platform, as they could also be connected to an I2C
452  *   running platform is reported through the &drm_bridge.ops flags. Bridge
459  *   decide which bridge to delegate a connector operation to. This mechanism
461  *   bridge drivers, improving security by storing function pointers in
464  *   In order to ease transition, bridge drivers may support both the old and
466  *   connected-related bridge operations. Connector creation is then controlled
469  *   %DRM_BRIDGE_ATTACH_NO_CONNECTOR flag, and bridge drivers shall then skip
471  *   be passed to the drm_bridge_attach() call for the downstream bridge.
472  *   Bridge drivers that implement the new model only shall return an error
475  *   should use the new model, and convert the bridge drivers they use if
482  * @bridge: bridge control structure
487  * chain, starting from the first bridge to the last. If at least one bridge
490  * Note: the bridge passed should be the one closest to the encoder.
496 drm_bridge_chain_mode_valid(struct drm_bridge *bridge,  in drm_bridge_chain_mode_valid()  argument
502 	if (!bridge)  in drm_bridge_chain_mode_valid()
505 	encoder = bridge->encoder;  in drm_bridge_chain_mode_valid()
506 	list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {  in drm_bridge_chain_mode_valid()
509 		if (!bridge->funcs->mode_valid)  in drm_bridge_chain_mode_valid()
512 		ret = bridge->funcs->mode_valid(bridge, info, mode);  in drm_bridge_chain_mode_valid()
524  * @bridge: bridge control structure
529  * encoder chain, starting from the first bridge to the last.
531  * Note: the bridge passed should be the one closest to the encoder
533 void drm_bridge_chain_mode_set(struct drm_bridge *bridge,  in drm_bridge_chain_mode_set()  argument
539 	if (!bridge)  in drm_bridge_chain_mode_set()
542 	encoder = bridge->encoder;  in drm_bridge_chain_mode_set()
543 	list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {  in drm_bridge_chain_mode_set()
544 		if (bridge->funcs->mode_set)  in drm_bridge_chain_mode_set()
545 			bridge->funcs->mode_set(bridge, mode, adjusted_mode);  in drm_bridge_chain_mode_set()
552  * @bridge: bridge control structure
557  * starting from the last bridge to the first. These are called before calling
560  * Note: the bridge passed should be the one closest to the encoder
562 void drm_atomic_bridge_chain_disable(struct drm_bridge *bridge,  in drm_atomic_bridge_chain_disable()  argument
568 	if (!bridge)  in drm_atomic_bridge_chain_disable()
571 	encoder = bridge->encoder;  in drm_atomic_bridge_chain_disable()
587 		if (iter == bridge)  in drm_atomic_bridge_chain_disable()
593 static void drm_atomic_bridge_call_post_disable(struct drm_bridge *bridge,  in drm_atomic_bridge_call_post_disable()  argument
596 	if (old_state && bridge->funcs->atomic_post_disable) {  in drm_atomic_bridge_call_post_disable()
601 							bridge);  in drm_atomic_bridge_call_post_disable()
605 		bridge->funcs->atomic_post_disable(bridge,  in drm_atomic_bridge_call_post_disable()
607 	} else if (bridge->funcs->post_disable) {  in drm_atomic_bridge_call_post_disable()
608 		bridge->funcs->post_disable(bridge);  in drm_atomic_bridge_call_post_disable()
615  * @bridge: bridge control structure
620  * starting from the first bridge to the last. These are called after completing
623  * If a bridge sets @pre_enable_prev_first, then the @post_disable for that
624  * bridge will be called before the previous one to reverse the @pre_enable
628  * Bridge A ---> Bridge B ---> Bridge C ---> Bridge D ---> Bridge E
630  * With pre_enable_prev_first flag enable in Bridge B, D, E then the resulting
632  * Bridge B, Bridge A, Bridge E, Bridge D, Bridge C.
634  * Note: the bridge passed should be the one closest to the encoder
636 void drm_atomic_bridge_chain_post_disable(struct drm_bridge *bridge,  in drm_atomic_bridge_chain_post_disable()  argument
642 	if (!bridge)  in drm_atomic_bridge_chain_post_disable()
645 	encoder = bridge->encoder;  in drm_atomic_bridge_chain_post_disable()
647 	list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {  in drm_atomic_bridge_chain_post_disable()
650 		if (!list_is_last(&bridge->chain_node, &encoder->bridge_chain)) {  in drm_atomic_bridge_chain_post_disable()
651 			next = list_next_entry(bridge, chain_node);  in drm_atomic_bridge_chain_post_disable()
654 				/* next bridge had requested that prev  in drm_atomic_bridge_chain_post_disable()
659 				/* Find the next bridge that has NOT requested  in drm_atomic_bridge_chain_post_disable()
680 					if (next == bridge)  in drm_atomic_bridge_chain_post_disable()
689 		drm_atomic_bridge_call_post_disable(bridge, old_state);  in drm_atomic_bridge_chain_post_disable()
693 			bridge = limit;  in drm_atomic_bridge_chain_post_disable()
698 static void drm_atomic_bridge_call_pre_enable(struct drm_bridge *bridge,  in drm_atomic_bridge_call_pre_enable()  argument
701 	if (old_state && bridge->funcs->atomic_pre_enable) {  in drm_atomic_bridge_call_pre_enable()
706 							bridge);  in drm_atomic_bridge_call_pre_enable()
710 		bridge->funcs->atomic_pre_enable(bridge, old_bridge_state);  in drm_atomic_bridge_call_pre_enable()
711 	} else if (bridge->funcs->pre_enable) {  in drm_atomic_bridge_call_pre_enable()
712 		bridge->funcs->pre_enable(bridge);  in drm_atomic_bridge_call_pre_enable()
719  * @bridge: bridge control structure
724  * starting from the last bridge to the first. These are called before calling
727  * If a bridge sets @pre_enable_prev_first, then the pre_enable for the
728  * prev bridge will be called before pre_enable of this bridge.
731  * Bridge A ---> Bridge B ---> Bridge C ---> Bridge D ---> Bridge E
733  * With pre_enable_prev_first flag enable in Bridge B, D, E then the resulting
735  * Bridge C, Bridge D, Bridge E, Bridge A, Bridge B.
737  * Note: the bridge passed should be the one closest to the encoder
739 void drm_atomic_bridge_chain_pre_enable(struct drm_bridge *bridge,  in drm_atomic_bridge_chain_pre_enable()  argument
745 	if (!bridge)  in drm_atomic_bridge_chain_pre_enable()
748 	encoder = bridge->encoder;  in drm_atomic_bridge_chain_pre_enable()
753 			limit = bridge;  in drm_atomic_bridge_chain_pre_enable()
757 				if (next == bridge)  in drm_atomic_bridge_chain_pre_enable()
761 					/* Found first bridge that does NOT  in drm_atomic_bridge_chain_pre_enable()
770 				/* Call requested prev bridge pre_enable  in drm_atomic_bridge_chain_pre_enable()
774 					/* At the first bridge to request prev  in drm_atomic_bridge_chain_pre_enable()
789 		if (iter == bridge)  in drm_atomic_bridge_chain_pre_enable()
797  * @bridge: bridge control structure
802  * starting from the first bridge to the last. These are called after completing
805  * Note: the bridge passed should be the one closest to the encoder
807 void drm_atomic_bridge_chain_enable(struct drm_bridge *bridge,  in drm_atomic_bridge_chain_enable()  argument
812 	if (!bridge)  in drm_atomic_bridge_chain_enable()
815 	encoder = bridge->encoder;  in drm_atomic_bridge_chain_enable()
816 	list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {  in drm_atomic_bridge_chain_enable()
817 		if (bridge->funcs->atomic_enable) {  in drm_atomic_bridge_chain_enable()
822 								bridge);  in drm_atomic_bridge_chain_enable()
826 			bridge->funcs->atomic_enable(bridge, old_bridge_state);  in drm_atomic_bridge_chain_enable()
827 		} else if (bridge->funcs->enable) {  in drm_atomic_bridge_chain_enable()
828 			bridge->funcs->enable(bridge);  in drm_atomic_bridge_chain_enable()
834 static int drm_atomic_bridge_check(struct drm_bridge *bridge,  in drm_atomic_bridge_check()  argument
838 	if (bridge->funcs->atomic_check) {  in drm_atomic_bridge_check()
843 							       bridge);  in drm_atomic_bridge_check()
847 		ret = bridge->funcs->atomic_check(bridge, bridge_state,  in drm_atomic_bridge_check()
851 	} else if (bridge->funcs->mode_fixup) {  in drm_atomic_bridge_check()
852 		if (!bridge->funcs->mode_fixup(bridge, &crtc_state->mode,  in drm_atomic_bridge_check()
877 	 * If bus format negotiation is not supported by this bridge, let's  in select_bus_fmt_recursive()
878 	 * pass MEDIA_BUS_FMT_FIXED to the previous bridge in the chain and  in select_bus_fmt_recursive()
894 		 * fine, as long as it does not access the bridge state.  in select_bus_fmt_recursive()
949  * It performs bus format negotiation between bridge elements. The negotiation
951  * @bridge.
954  * bridge element and testing them one by one. The test is recursive, meaning
957  * transcoded to the requested output format. When a bridge element does not
959  * the next bridge element will have to try a different format. If none of the
974  * bridge element that lacks this hook and asks the previous element in the
975  * chain to try MEDIA_BUS_FMT_FIXED. It's up to bridge drivers to decide what
981 drm_atomic_bridge_chain_select_bus_fmts(struct drm_bridge *bridge,  in drm_atomic_bridge_chain_select_bus_fmts()  argument
986 	struct drm_encoder *encoder = bridge->encoder;  in drm_atomic_bridge_chain_select_bus_fmts()
1031 		ret = select_bus_fmt_recursive(bridge, last_bridge, crtc_state,  in drm_atomic_bridge_chain_select_bus_fmts()
1043 drm_atomic_bridge_propagate_bus_flags(struct drm_bridge *bridge,  in drm_atomic_bridge_propagate_bus_flags()  argument
1051 	bridge_state = drm_atomic_get_new_bridge_state(state, bridge);  in drm_atomic_bridge_propagate_bus_flags()
1053 	/* No bridge state attached to this bridge => nothing to propagate. */  in drm_atomic_bridge_propagate_bus_flags()
1057 	next_bridge = drm_bridge_get_next_bridge(bridge);  in drm_atomic_bridge_propagate_bus_flags()
1061 	 * display_info flags for the last bridge, and propagate the input  in drm_atomic_bridge_propagate_bus_flags()
1062 	 * flags of the next bridge element to the output end of the current  in drm_atomic_bridge_propagate_bus_flags()
1063 	 * bridge when the bridge is not the last one.  in drm_atomic_bridge_propagate_bus_flags()
1075 		 * No bridge state attached to the next bridge, just leave the  in drm_atomic_bridge_propagate_bus_flags()
1085 	 * Propagate the output flags to the input end of the bridge. Again, it's  in drm_atomic_bridge_propagate_bus_flags()
1094  * drm_atomic_bridge_chain_check() - Do an atomic check on the bridge chain
1095  * @bridge: bridge control structure
1102  * starting from the last bridge to the first. These are called before calling
1108 int drm_atomic_bridge_chain_check(struct drm_bridge *bridge,  in drm_atomic_bridge_chain_check()  argument
1117 	if (!bridge)  in drm_atomic_bridge_chain_check()
1120 	ret = drm_atomic_bridge_chain_select_bus_fmts(bridge, crtc_state,  in drm_atomic_bridge_chain_check()
1125 	encoder = bridge->encoder;  in drm_atomic_bridge_chain_check()
1130 		 * Bus flags are propagated by default. If a bridge needs to  in drm_atomic_bridge_chain_check()
1143 		if (iter == bridge)  in drm_atomic_bridge_chain_check()
1152  * drm_bridge_detect - check if anything is attached to the bridge output
1153  * @bridge: bridge control structure
1155  * If the bridge supports output detection, as reported by the
1156  * DRM_BRIDGE_OP_DETECT bridge ops flag, call &drm_bridge_funcs.detect for the
1157  * bridge and return the connection status. Otherwise return
1161  * The detection status on success, or connector_status_unknown if the bridge
1164 enum drm_connector_status drm_bridge_detect(struct drm_bridge *bridge)  in drm_bridge_detect()  argument
1166 	if (!(bridge->ops & DRM_BRIDGE_OP_DETECT))  in drm_bridge_detect()
1169 	return bridge->funcs->detect(bridge);  in drm_bridge_detect()
1176  * @bridge: bridge control structure
1179  * If the bridge supports output modes retrieval, as reported by the
1180  * DRM_BRIDGE_OP_MODES bridge ops flag, call &drm_bridge_funcs.get_modes to
1187 int drm_bridge_get_modes(struct drm_bridge *bridge,  in drm_bridge_get_modes()  argument
1190 	if (!(bridge->ops & DRM_BRIDGE_OP_MODES))  in drm_bridge_get_modes()
1193 	return bridge->funcs->get_modes(bridge, connector);  in drm_bridge_get_modes()
1199  * @bridge: bridge control structure
1202  * If the bridge supports output EDID retrieval, as reported by the
1203  * DRM_BRIDGE_OP_EDID bridge ops flag, call &drm_bridge_funcs.edid_read to get
1209 const struct drm_edid *drm_bridge_edid_read(struct drm_bridge *bridge,  in drm_bridge_edid_read()  argument
1212 	if (!(bridge->ops & DRM_BRIDGE_OP_EDID))  in drm_bridge_edid_read()
1215 	return bridge->funcs->edid_read(bridge, connector);  in drm_bridge_edid_read()
1220  * drm_bridge_hpd_enable - enable hot plug detection for the bridge
1221  * @bridge: bridge control structure
1227  * called with @data when an output status change is detected by the bridge,
1231  * bridge->ops. This function shall not be called when the flag is not set.
1235  * the bridge.
1237 void drm_bridge_hpd_enable(struct drm_bridge *bridge,  in drm_bridge_hpd_enable()  argument
1242 	if (!(bridge->ops & DRM_BRIDGE_OP_HPD))  in drm_bridge_hpd_enable()
1245 	mutex_lock(&bridge->hpd_mutex);  in drm_bridge_hpd_enable()
1247 	if (WARN(bridge->hpd_cb, "Hot plug detection already enabled\n"))  in drm_bridge_hpd_enable()
1250 	bridge->hpd_cb = cb;  in drm_bridge_hpd_enable()
1251 	bridge->hpd_data = data;  in drm_bridge_hpd_enable()
1253 	if (bridge->funcs->hpd_enable)  in drm_bridge_hpd_enable()
1254 		bridge->funcs->hpd_enable(bridge);  in drm_bridge_hpd_enable()
1257 	mutex_unlock(&bridge->hpd_mutex);  in drm_bridge_hpd_enable()
1262  * drm_bridge_hpd_disable - disable hot plug detection for the bridge
1263  * @bridge: bridge control structure
1267  * Once this function returns the callback will not be called by the bridge
1271  * bridge->ops. This function shall not be called when the flag is not set.
1273 void drm_bridge_hpd_disable(struct drm_bridge *bridge)  in drm_bridge_hpd_disable()  argument
1275 	if (!(bridge->ops & DRM_BRIDGE_OP_HPD))  in drm_bridge_hpd_disable()
1278 	mutex_lock(&bridge->hpd_mutex);  in drm_bridge_hpd_disable()
1279 	if (bridge->funcs->hpd_disable)  in drm_bridge_hpd_disable()
1280 		bridge->funcs->hpd_disable(bridge);  in drm_bridge_hpd_disable()
1282 	bridge->hpd_cb = NULL;  in drm_bridge_hpd_disable()
1283 	bridge->hpd_data = NULL;  in drm_bridge_hpd_disable()
1284 	mutex_unlock(&bridge->hpd_mutex);  in drm_bridge_hpd_disable()
1290  * @bridge: bridge control structure
1293  * Bridge drivers shall call this function to report hot plug events when they
1299 void drm_bridge_hpd_notify(struct drm_bridge *bridge,  in drm_bridge_hpd_notify()  argument
1302 	mutex_lock(&bridge->hpd_mutex);  in drm_bridge_hpd_notify()
1303 	if (bridge->hpd_cb)  in drm_bridge_hpd_notify()
1304 		bridge->hpd_cb(bridge->hpd_data, status);  in drm_bridge_hpd_notify()
1305 	mutex_unlock(&bridge->hpd_mutex);  in drm_bridge_hpd_notify()
1311  * of_drm_find_bridge - find the bridge corresponding to the device node in
1312  *			the global bridge list
1321 	struct drm_bridge *bridge;  in of_drm_find_bridge()  local
1325 	list_for_each_entry(bridge, &bridge_list, list) {  in of_drm_find_bridge()
1326 		if (bridge->of_node == np) {  in of_drm_find_bridge()
1328 			return bridge;  in of_drm_find_bridge()
1339 MODULE_DESCRIPTION("DRM bridge infrastructure");