drm_dp_get_vc_payload_bw(9)

💅 drm_dp_get_vc_payload_bw(9) 💅

okay so bestie, welcome to the Kernel API Manual, this one's about drm_dp_get_vc_payload_bw and it's lowkey the math girlie of the DisplayPort MST world 🎀

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✨ NAME ✨

drm_dp_get_vc_payload_bw — get the VC payload BW for an MTP link 💖

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🌸 SYNOPSIS 🌸

fixed20_12 drm_dp_get_vc_payload_bw (int link_rate , int link_lane_count );

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🦋 ARGUMENTS 🦋

• link_rate — the link rate, and it's in 10kbits/s units bestie, don't forget the units 💅
• link_lane_count — the lane count. that's it. that's the whole vibe 🫶

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👑 DESCRIPTION 👑

So basically this function calculates the total bandwidth of a MultiStream Transport link. iconic behavior, honestly ✨

The value it hands back is in units of PBNs/(timeslots/1 MTP). which sounds like a lot but it's giving very useful, because you can use this number to convert the number of PBNs required for a given stream into the number of timeslots that stream requires in each MTP. like a little translation service for your streams, iykyk 💫

And what does it return? The BW / timeslot value, in 20.12 fixed point format. no cap, that's the return 🌈

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🔥 SEE ALSO 🔥

The kernel file is ./drivers/gpu/drm/display/drm_dp_mst_topology.c — go read it, it's right there 🧚

and then the whole friend group, in order, no one left out:

• 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_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_root_conn_atomic_check(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)

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and that's the whole page bestie!! mwah 💋

this little transmission came straight out of ./drivers/gpu/drm/display, dated October 2026, and the page title is drm_dp_get_vc_payload_bw(9) — slay, go forth and calculate your bandwidth 🦋💖✨