usb4_dp_port...ed_bandwidth(9)

💅 usb4_dp_port...ed_bandwidth(9) — Kernel API Manual, bestie edition 💅

okay so this page is from the Kernel API Manual, and the actual function being explained is usb4_dp_port_set_estimated_bandwidth. It’s giving bandwidth-manager realness, and yes, we’re gonna get into every detail. 🫶

---

✨ NAME ✨

usb4_dp_port_set_estimated_bandwidth — set estimated bandwidth. That’s the whole vibe. 💖

---

🎀 SYNOPSIS 🎀

int usb4_dp_port_set_estimated_bandwidth (struct tb_port *port , int bw
);

---

🦋 ARGUMENTS 🦋

• port — DP IN adapter. That’s the port bestie in question. 💅
• bw — Estimated bandwidth in Mb/s. Yes, Mb/s, keep that unit in your notes. 📝

---

🌸 DESCRIPTION 🌸

This one sets the estimated bandwidth to bw. Iconic.

But listen: set the granularity by calling usb4_dp_port_set_granularity before calling this. Order matters, no cap. The bw is rounded down to the closest granularity multiplier. So it’s not out here doing chaotic extra math — it’s rounding down, periodt. ✨

---

🔥 RETURN 🔥

• 0 — On success. Slay. ✅
• -EOPNOTSUPP — If the adapter does not support this. Rude, but documented. 💀
• Negative errno — Another error occurred. Sorry bestie. 😭

---

👑 SEE ALSO 👑

Kernel file ./drivers/thunderbolt/usb4.c — and the whole iconic lineup:

usb4_switch_check_wakes(9), usb4_switch_setup(9), usb4_switch_configuration_valid(9), usb4_switch_read_uid(9), usb4_switch_drom_read(9), usb4_switch_lane_bonding_possible(9), usb4_switch_set_wake(9), usb4_switch_set_sleep(9), usb4_switch_nvm_sector_size(9), usb4_switch_nvm_read(9), usb4_switch_nvm_set_offset(9), usb4_switch_nvm_write(9), usb4_switch_nvm_authenticate(9), usb4_switch_nvm_authenticate_status(9), usb4_switch_credits_init(9), usb4_switch_query_dp_resource(9), usb4_switch_alloc_dp_resource(9), usb4_switch_dealloc_dp_resource(9), usb4_port_index(9), usb4_switch_map_pcie_down(9), usb4_switch_map_usb3_down(9), usb4_switch_add_ports(9), usb4_switch_remove_ports(9), usb4_port_unlock(9), usb4_port_hotplug_enable(9), usb4_port_reset(9), usb4_port_configure(9), usb4_port_unconfigure(9), usb4_port_configure_xdomain(9), usb4_port_unconfigure_xdomain(9), usb4_port_sb_read(9), usb4_port_sb_write(9), usb4_port_router_offline(9), usb4_port_router_online(9), usb4_port_enumerate_retimers(9), usb4_port_clx_supported(9), usb4_port_asym_supported(9), usb4_port_asym_set_link_width(9), usb4_port_asym_start(9), usb4_port_margining_caps(9), usb4_port_hw_margin(9), usb4_port_sw_margin(9), usb4_port_sw_margin_errors(9), usb4_port_retimer_set_inbound_sbtx(9), usb4_port_retimer_unset_inbound_sbtx(9), usb4_port_retimer_is_last(9), usb4_port_retimer_is_cable(9), usb4_port_retimer_nvm_sector_size(9), usb4_port_retimer_nvm_set_offset(9), usb4_port_retimer_nvm_write(9), usb4_port_retimer_nvm_authenticate(9), usb4_port_retimer_nvm_authenticate_status(9), usb4_port_retimer_nvm_read(9), usb4_usb3_port_max_link_rate(9), usb4_usb3_port_allocated_bandwidth(9), usb4_usb3_port_allocate_bandwidth(9), usb4_usb3_port_release_bandwidth(9), usb4_dp_port_set_cm_id(9), usb4_dp_port_bandwidth_mode_supported(9), usb4_dp_port_bandwidth_mode_enabled(9), usb4_dp_port_set_cm_bandwidth_mode_supported(9), usb4_dp_port_group_id(9), usb4_dp_port_set_group_id(9), usb4_dp_port_nrd(9), usb4_dp_port_set_nrd(9), usb4_dp_port_granularity(9), usb4_dp_port_set_granularity(9), usb4_dp_port_allocated_bandwidth(9), usb4_dp_port_allocate_bandwidth(9), usb4_dp_port_requested_bandwidth(9), usb4_pci_port_set_ext_encapsulation(9), usb4_pci_port_ltssm_state(9).

---

source/version: ./drivers/thunderbolt • date: October 2026 • page: usb4_dp_port...ed_bandwidth(9) — mwah, bye bestie 💖✨