drm_dp_mst_...atomic_check(9)

💅 drm_dp_mst_...atomic_check(9) 💅

okay so welcome to the Kernel API Manual page for drm_dp_mst_...atomic_check(9) — aka the page about drm_dp_mst_root_conn_atomic_check, and bestie, it is literally giving “serialize those CRTC commits” energy.

✨ NAME ✨

drm_dp_mst_root_conn_atomic_check — Serialize CRTC commits on MST-capable connectors operating in SST mode

🎀 SYNOPSIS 🎀

int drm_dp_mst_root_conn_atomic_check (struct drm_connector_state
       *new_conn_state , struct drm_dp_mst_topology_mgr *mgr );

🌸 ARGUMENTS 🌸

• new_conn_state — The new connector state of the drm_connector. That’s the fresh state bestie 💅
• mgr — The MST topology manager for the drm_connector. The manager in question, no cap.

🦋 DESCRIPTION 🦋

okay so here’s the situation: MST uses fake drm_encoder structs, which means the generic atomic modesetting code isn’t able to serialize non-blocking commits happening on the real DP connector of an MST topology switching into/away from MST mode — as the CRTC on the real DP connector and the CRTCs on the connector’s MST topology will never share the same drm_encoder. messy 😭

This function takes care of this serialization issue, by checking a root MST connector’s atomic state to determine if it is about to have a modeset — and then pulling in the MST topology state if so, along with adding any relevant CRTCs to drm_dp_mst_topology_state.pending_crtc_mask. slay ✨

Drivers implementing MST must call this function from the drm_connector_helper_funcs.atomic_check hook of any physical DP drm_connector capable of driving MST sinks. periodt.

👑 RETURN 👑

0 on success, negative error code otherwise. zero is the main character; negative is the villain arc 😭

💖 SEE ALSO 💖

• Kernel file: ./drivers/gpu/drm/display/drm_dp_mst_topology.c
• dp mst helper(9)
• Branch device and port refcounting(9)
• drm_dp_mst_get_mstb_malloc(9)
• drm_dp_mst_put_mstb_malloc(9)
• drm_dp_mst_get_port_malloc(9)
• drm_dp_mst_put_port_malloc(9)
• drm_dp_mst_topology_try_get_mstb(9)
• drm_dp_mst_topology_get_mstb(9)
• drm_dp_mst_topology_put_mstb(9)
• drm_dp_mst_topology_try_get_port(9)
• drm_dp_mst_topology_get_port(9)
• drm_dp_mst_topology_put_port(9)
• drm_dp_mst_dpcd_read(9)
• drm_dp_mst_dpcd_write(9)
• drm_dp_mst_connector_late_register(9)
• drm_dp_mst_connector_early_unregister(9)
• drm_dp_add_payload_part1(9)
• drm_dp_remove_payload_part1(9)
• drm_dp_remove_payload_part2(9)
• drm_dp_add_payload_part2(9)
• drm_dp_get_vc_payload_bw(9)
• drm_dp_read_mst_cap(9)
• drm_dp_mst_topology_mgr_set_mst(9)
• drm_dp_mst_topology_queue_probe(9)
• drm_dp_mst_topology_mgr_suspend(9)
• drm_dp_mst_topology_mgr_resume(9)
• drm_dp_mst_hpd_irq_handle_event(9)
• drm_dp_mst_hpd_irq_send_new_request(9)
• drm_dp_mst_detect_port(9)
• drm_dp_mst_edid_read(9)
• drm_dp_mst_get_edid(9)
• drm_dp_atomic_find_time_slots(9)
• drm_dp_atomic_release_time_slots(9)
• drm_dp_mst_atomic_setup_commit(9)
• drm_dp_mst_atomic_wait_for_dependencies(9)
• drm_dp_mst_update_slots(9)
• drm_dp_check_act_status(9)
• drm_dp_calc_pbn_mode(9)
• drm_dp_mst_dump_topology(9)
• drm_dp_mst_port_downstream_of_parent(9)
• drm_dp_mst_add_affected_dsc_crtcs(9)
• drm_dp_mst_atomic_enable_dsc(9)
• drm_dp_mst_atomic_check_mgr(9)
• drm_dp_mst_atomic_check(9)
• drm_atomic_get_mst_topology_state(9)
• drm_atomic_get_old_mst_topology_state(9)
• drm_atomic_get_new_mst_topology_state(9)
• drm_dp_mst_topology_mgr_init(9)
• drm_dp_mst_topology_mgr_destroy(9)
• drm_dp_mst_register_i2c_bus(9)
• drm_dp_mst_unregister_i2c_bus(9)
• drm_dp_mst_is_virtual_dpcd(9)
• drm_dp_mst_aux_for_parent(9)
• drm_dp_mst_dsc_aux_for_port(9)

🫶 cute sign-off: this came from the Kernel API Manual, source ./drivers/gpu/drm/display, dated October 2026, page drm_dp_mst_...atomic_check(9). bye bestie, go serialize those commits 💅✨