usb4_switch_version(9)

💖 NAME 💖

okay so bestie, in the Kernel API Manual we have usb4_switch_version — and it literally returns the USB4 version of the router. no cap. ✨

🛠️ SYNOPSIS 🛠️

unsigned int usb4_switch_version (const struct tb_switch *sw );

🧚 ARGUMENTS 🧚

• sw — the router to check, bestie. that’s the whole vibe. 🫶

📦 RETURN 📦

It hands you the major version of the USB4 router: 1 for v1, 2 for v2, and so on. You can call it on a pre-USB4 router too, and in that case it returns 0. so if you see 0, that’s your lowkey not-USB4 signal 💅

👀 SEE ALSO 👀

Kernel file ./drivers/thunderbolt/tb.h plus this whole iconic squad of references:

• struct tb_nvm(9)
• enum tb_switch_tmu_mode(9)
• struct tb_switch_tmu(9)
• struct tb_switch(9)
• struct tb_bandwidth_group(9)
• struct tb_port(9)
• struct usb4_port(9)
• struct tb_retimer(9)
• struct tb_path_hop(9)
• enum tb_path_port(9)
• struct tb_path(9)
• struct tb_cm_ops(9)
• tb_upstream_port(9)
• tb_is_upstream_port(9)
• tb_port_has_remote(9)
• tb_domain_event(9)
• tb_switch_for_each_port(9)
• tb_switch_downstream_port(9)
• tb_switch_depth(9)
• tb_switch_is_icm(9)
• tb_switch_tmu_is_configured(9)
• tb_switch_tmu_is_enabled(9)
• tb_switch_clx_is_enabled(9)
• tb_port_path_direction_downstream(9)
• tb_for_each_port_on_path(9)
• tb_for_each_upstream_port_on_path(9)
• tb_path_for_each_hop(9)
• tb_downstream_route(9)
• tb_xdomain_downstream_port(9)
• tb_switch_is_usb4(9)
• enum usb4_sb_target(9)
• enum usb4_margin_sw_error_counter(9)
• struct usb4_port_margining_params(9)

mwah 💋 source/version: ./drivers/thunderbolt · date: October 2026 · usb4_switch_version(9) — bye bestie, go check those routers 💅✨