tb_upstream_port(9)

✨ tb_upstream_port(9) ✨

okay so real talk, this is a page from the Kernel API Manual about tb_upstream_port, and honestly? it's a little guy that does exactly one thing and does it cute. let's get into it bestie 💅

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🌸 NAME 🌸

tb_upstream_port — return the upstream port of a switch

like literally that's the whole job. find the upstream port. slay.

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🦋 SYNOPSIS 🦋

struct tb_port * tb_upstream_port (struct tb_switch *sw );

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🎀 ARGUMENTS 🎀

• sw — Router 🫶 (yes, that's the whole description. the router. that's the vibe.)

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💖 DESCRIPTION 💖

okay so here's the tea: every switch has an upstream port. every single one. and for the root switch, that upstream port is the NHI. iconic behavior honestly 👑

but here's the part you need to know, and i'm saying this with love: during switch alloc/init, tb_upstream_port->remote may be NULL, even for non-root switches. and on the NHI port, remote is always NULL. so like… don't come for it when it's NULL, it's literally going through something 😭

no cap, check for that NULL before you go dereferencing, bestie. that's not me being dramatic, that's just the facts.

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⭐ RETURN ⭐

Pointer to struct tb_port. 💫

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🌈 SEE ALSO 🌈

Kernel file ./drivers/thunderbolt/tb.h and the whole friend group:

• 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_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)
• usb4_switch_version(9)
• tb_switch_is_usb4(9)
• enum usb4_sb_target(9)
• enum usb4_margin_sw_error_counter(9)
• struct usb4_port_margining_params(9)

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and that's the page!! 🧚 mwah 💋 ok bye, this came from ./drivers/thunderbolt, dated October 2026 — go off, driver directory, we love you, periodt 💜🔥